Module 10.1

Authors Dr John Pyne and Dr Ian McColl
Contact John regarding this module or to send additional images.

Introduction

Blood vessel morphology is another feature of dermoscopy assisting diagnosis. Blood vessels can be visualized in melanocytic, non-melanocytic, benign and malignant lesions. Generally, benign tumours have vessel patterns which are regular in shape, size and distribution. Malignant tumours often have irregular morhpology in vessel features and distribution. Other dermoscopy features are usually present although in some cases vessels may be the only feature evident. The shape of the vessels is often significant in diagnosis. The contribution vessels make to the diagnosis varies from nothing (e.g.blue naevus) to just about everything (e.g. red lacunes in haemangioma). It is very important to recognized characteristic vessels in some malignant tumours (e.g. polymorphic vessels in amelanotic melanoma) because this may be the only clue to the diagnosis. Diagnosis is attained by considering all the evidence presented and vessel morphology plays a variable contribution over the range of biological variation being examined. Vascular definition is important, e.g. in nodular BCC, the tumour islands push the arborizing vessels up closer to the surface resulting in sharper vessel definition (clearer focus) compared to the crown vessels in sebaceous gland hyperplasia where the vessels are deeper and out of focus thus lacking definition.

Enhancing vessel visualization

There are a number of things clinicians can do to optimise vessel examination.
1. Use polarized dermoscopy to reduce light reflection from the stratum corneum. Non-polarized dermoscopy does not highlight vessels as well.

2. Use clear gel between the dermatoscope glass plate and the lesion. This reduces pressure on the vessels. Excess pressure squashes blood out of the vessels rendering the vessels relatively invisible.

3. Non-contact dermoscopy eliminates vessel compression.

4. Take digital photos of your own excisions to build up your own “library” of dermoscopy which includes a diverse range of vessels.

5.The Skin Cancer Society Blog - several of the reference digital photos of vessels listed below are shown on the Society Blog.

6. To begin your familiarization with connecting vessel patterns to specific diagnoses go to the Society Blog, Click on Dermoscopy Atlas, then type in vessels in search, this will lead you into an overall view of vessel types associated with diagnosis.



Vascular Architecture, Morphology, Diagnostic Correlation
The following presentation sets out vessel architecture and interpretation.

Red Lacunes
Sharply demarcated globular structures, red violaceous, brown blue or black(thrombosed). Haemangiomas and angiokeratomas. Also see venous lake on the Blog.

Crown Vessels
Radial wreath-like vessels surrounding white-yellow globules. Check sebaceous gland hyperplasia on the Blog.

String of Pearls
Globular vessels in serpiginous loops. Check Clear Cell Acanthoma on the Blog (including the Dermoscopy Atlas)

Comma Vessels
Comma shaped vessels, usually slightly out of focus. Compound and dermal naevi. Also in Clark naevi. Check naevi (esp Compound).

Hairpin Vessels
Elongated loops looking like bent hairpins. Fine and surrounded by a white halo, seborrhoeic keratosis or keratinizing tumour. Check SCC and Seborrhoeic ketarosis on the Blog.

Glomerular Vessels
Small and fine coils like in renal glomerulous. Bowen’s , Venous stasis, Melanoma. Check Bowens.

Arborizing Vessels
Sharp resolution, similar to branches on a tree. Check nodular BCC on the Blog.

Irregular Polymorphous Vessels
Multiple irregular distribution, size and shaped vessels. Check melanoma on Blog (and altas)

Corkscrew Vessels
Irregular and thickened coiled vessels. Check primary melanoma and melanoma metastasis.

Milky Areas
Irregular blotchy areas, often structureless. Check Melanoma.

The image below shows:a "String of Pearls" in a Clear Cell Acanthoma


Glomerular Vessels in Bowen’s (SCC in situ)

Ash Marghoob on the predictive value of blood vessels in dermoscopy.



Arborizing Vessels in Nodular BCC

Have a look at this Blog case by Alan Cameron looking at the vessel patterns in several BCCs.

The Boab Tree vessels of Merkel cell carcinoma
If you are ever going to diagnose this tumour dermatoscopically then this description of vessel architecture from Hilton Beck might just help you!



Polymorphous vessels in melanoma.

Polarising dermatoscopes help to highlight vascular features.
Alan Cameron looks at the use of Polarising images in this case from the Blog

Alan goes into more detail on polarising contact and non contact photography in this case from the Blog



Melanoma showing Milky Areas and Pin Point (Dotted) Vessels.
This is an interesting article from Medscape discussing the use of dermoscopy in diagnosing amelanotic or hypomelanotic melanomas

There is also a recent article in the Archives of Dermatology on the dermoscopic diagnosis of hypomelanotic and amelanotic melanomas. Download it here



Melanoma showing Milky Areas and Pin Point (Dotted) Vessels.
These were the results of Menzies paper on discriminating dermatoscopic features of hypo and amelanotic melanomas.
Results The most significant negative predictors of melanoma were having multiple (>3) milialike cysts (odds ratio, 0.09; 95% confidence interval, 0.01-0.64), comma vessels with a regular distribution (0.10; 0.01-0.70), comma vessels as the predominant vessel type (0.16; 0.05-0.52), symmetrical pigmentation pattern (0.18; 0.09-0.39), irregular blue-gray globules (0.20; 0.05-0.87), and multiple blue-gray globules (0.28; 0.10-0.81). The most significant positive predictors were having a blue-white veil (odds ratio,13; 95% confidence interval, 3.9-40.0), scarlike depigmentation (4.4; 2.4-8.0), multiple blue-gray dots (3.5; 1.9-6.4), irregularly shaped depigmentation (3.3; 2.0-5.3), irregular brown dots/globules (3.2; 1.8-5.6), 5 to 6 colors (3.2; 1.6-6.3), and predominant central vessels (3.1; 1.6-6.0). A simple model distinguishing melanomas from all nonmelanomas had a sensitivity of 70% and a specificity of 56% in the test set. A model distinguishing all malignant lesions from benign lesions had a sensitivity of 96% and a specificity of 37%.



We are still struggling to describe vessels and determine to what extent we can rely on vessel morphology to diagnose both pigmented and non pigmented lesions. Harald Kittler has tried to rationalise our terminology in this field. Alan Cameron presents this concept in a PDF file you can download here. It is probably worthwhile looking at this file now before reading further . I would then advise going through it again at the end of Module 10.3 and I will link to it again at that point.IMCC



The vessels we see through the dermatoscope depend on the thickness of the skin we are examining and the thickness of the tumour. Skin tumours get their blood supply from the dermal plexus.The vessels come off as loops. If a tumour is thin then seen from above these short loops look like dots whereas if the tumour is thicker the loops are longer and in spreading over the lesion they look like hairpins when viewed obliquely.These hairpins are best seen at the edge of the lesion. With keratinocytic tumours these hairpin vessels have a clear halo around them due to ensheathing keratinocytes.This feature is not present in melanocytic lesions.
As the tumour grows and thickens the vessels become more variable with twisting and sometimes glomerular like areas being seen. The vessels also tend to course over the surface of the tumour.
Image courtesy of Dr Alan Cameron


From a practical point of view an analysis of vessels is useful in considering a diagnosis of BCC, Bowen's disease and amelanotic melanoma. In BCC the vessels are described as arborising, gradually breaking up into smaller vessels as they course over the surface of the nodular lesion. In melanoma the predominant pattern seen depends on the thickness of the lesion. Thin amelanotic melanomas will show dot vessels with short loops being seen end on. As the thickness of the lesion increases between 0.5 and 2 mms then some hairpin loops may be seen along with the dot vessels but the arrangement of vessels remains regular. As the tumour thickens above 3 mms the vessels become irregular and dermal vessels course over the surface of the tumour giving what are described as linear irregular vessels. These can look like the arborising vessels of a nodular BCC but they are not as obviously arborising because the branching is less marked.

It is easier to diagnose thin amelanotic melanomas using the dot and loop vessel patterns than to diagnose thicker lesions.


Dot vessels are also a feature of Spitz nevi and are seen in any thin skin tumour.
Non pigmented Bowen's disease has characteristic glomerular vessels often arranged in clusters throughout the lesion. When the Bowen's is pigmented as in the image below there are also brown globules positioned around and among the glomerular vessels.

Module 10.2

Diagnosing amelanotic melanoma on the basis of its vascular structures alone isn’t the easiest thing to do. Generally over all these lesions have a pinkish hue on dermoscopy. A lack of pigment means that the vessels can be fairly easily viewed with the dermatoscope. A polarised dermatoscope such as the dermlite pro allows you to see the vessels without putting any pressure on the actual skin itself. As soon as you put pressure with a plate on the skin you will tend to occlude some of the overlying vessels or at least the more superficial vessels. If you suspect that something is an amelanotic melanoma then you are going to look for dot vessels or glomerular vessels or irregular linear polymorphous vessels and sometimes regular hairpin vessels. There is commonly an assortment of vessels seen rather than the more predominant pattern that is seen in dermal nevi with comma vessels or basal cell carcinoma with the arborising vessels. However spitz nevi can also have dotted vessels and also show that pinkish red colour that we sometimes ascribe to an amelanotic melanoma.

Menzies et al on Dermatoscopic features of amelanotic and hypomelanotic melanomas. Archives of Derm Sept 2008



When you are examining vessels you also have to take into consideration what the surrounding vascular pattern is. On the face vessels are a lot more superficial than they are on the back with a dermal plexus localised much lower or much deeper in the skin. Facial skin is quite thin and there is effacement of the retie ridges so these vessels are easily seen on the facial lesions. It is much easier to diagnose an amelanotic melanoma on the back than it is on the face.

The arrangement of vessels on the surface of a tumour is often related to the thickness of the tumour. If the tumour is relatively thin you will have small short dot like vessels feeding from the dermal plexus. As the tumour thickens these feeding vessels will lengthen and will become more hairpin like. An even thicker lesion will then have an orderly arrangement of vessels over the surface thereby simulating a basal cell skin cancer.

These hairpin or loop like vessels may be surrounded by a whitish halo especially in keratinising tumours so this feature of a white halo around these hairpin like vessels is seen in lesions such as keratoacanthomas, squamous cell carcinomas, seborrhoeic keratoses and some warts. The whitish halo is made up of keratinocytes surrounding the feeding vessels.The highlighted case from the Skin Cancer Blog shows this very well in a seborrhoeic keratosis.

Vessels such as arborising, crown and comma vessels are regarded as non loop types.

The distribution of vessels in a lesion can help. In a nodular BCC the vessels are often overlying the nodular component and they are arborising or tree like i.e. the successive divisions get thinner. In a keratoacanthoma you will see hairpin vessels and they tend to be localised around the outside of the lesion. You may also remember that with warts if you pare them you will get bleeding throughout the lesion so the hairpin vessels in warts are scattered over the entire area of the wart.

Melanocytic lesions, which have both dot and hairpin vessels do not have the white halo around them. This is a very important differentiating point from keratinocytic tumours.



Dot vessels and glomerular (coiled) vessels are also a feature of Bowen’s disease, particularly the glomerular vessels. Bowen’s disease often occurs on the lower legs and in this area, because of venous stasis, using vessels alone is going to be a problem unless you concentrate on the surrounding vessel structures as well.Venous stasis tends to give dot vessels but they will be all around the area and not just confined to a lesion. However on other parts of the body glomerular and dot vessels can be quite useful in diagnosing Bowen’s disease in a lesion which does not have a lot of surface scale. Fortunately these lesions are better diagnosed clinically.




Dot vessels can also be seen in the lower legs in people with venous congestion so the diagnosis of amelanotic melanoma in these areas using dot vessels alone is not very specific. Always look at the vascular pattern of the surrounding skin.



The superficial BCC still has arborising vessels but they may not be as well defined or in focus as those seen on the surface of a nodular BCC. However when confronted by a pink lesion on the back or leg and having to decide between a superficial BCC, Scc in situ or amelanotic melanoma or even psoriasis, the vessel pattern can help. It will be glomerular in SCC in situ, dot in amelanotic melanoma and arborising in superficial BCC. Psoriasis can give dot vessels but there should be more than one lesion and scraping should reveal some scale.



Sometimes the vascular pattern in a lesion is just plain unusual. This was a nodular BCC on histology but shows a remarkable vascular pattern described as coral reef like by Dr Peter Bourne who presented the case.

View this case in the Blog


Actinic keratosis vessels- strawberry appearance.

These lesions show erythema, with a pink-to-red pseudonetwork surrounding the hair follicles
white-to-yellow surface scale,fine, linear-wavy vessels surrounding the hair follicles and also hair follicle openings filled with yellowish keratotic plugs and/or surrounded by a white halo.

Reference I. Zalaudek, J. Giacomel, G. Argenziano, R. Hofmann-Wellenhof, T. Micantonio, A. Di Stefani, M. Oliviero, H. Rabinovitz, H.P. Soyer, K. Peris (2006) Dermoscopy of facial nonpigmented actinic keratosis. British Journal of Dermatology 2006: 155 (5) , 951–956




Dermatofibromas Vascular structures are found in 29 to 49% of dermatofibromas, including erythema, dotted vessels, comma vessels, hairpin vessels, glomerular vessels, telangiectasias, linear-irregular vessels, polymorphous/atypical vessels.Dermatofibromas can mimic even an amelanotic melanoma dermatoscopically. However clinically the pinch test is usually diagnostic.

Dermoscopy of dermatofibromas. A Prospective Morphological Study of 412 Cases
P. Zaballos, S. Puig, A. Llambrich, J. Malvehy, Arch Dermatol. 2008;144(1):75-83

The other firm papule or nodule that you might come accross is a pilomatrixoma. This lesion is found on the cheeks of children. Generally it is skin coloured but feels very firm because of the calcification commonly found inside it. The dermatoscopic features of this lesion were described in the following article.
Images of a Pilomatrixoma can be viewed at Dermatlas





The crown vessels of sebaceous hyperplasia coursing into but not crossing the midline of the lesion. The lesional yellow white colour is characteristic of this lesion.

See these other examples from the Blog

Module 10.3

It has been suggested that the vascular pattern should be looked at in a sequential fashion. If you see arborising vessels coursing over the surface of the lesion then it is likely to be a basal cell skin cancer of the nodular type. Crown vessels are a specific feature of sebaceous gland hyperplasia and they are generally centred or arranged around a yellowish plug made up of the enlargement of sebaceous glands. Comma vessels if they are seen tend to make you think the lesion is a dermal nevus.The comma vessels are generally scattered across the tumour surface. If you then look and what you see are pinpoint and hairpin vessels then look to see if the hairpin vessels have a white halo around them. If they have it is likely to be a keratinocytic tumour. If they do not have then you may have an amelanotic melanoma on your hands. However spitz nevi can also have both hairpin and dot vessels. The differentiating feature is that the vessels in Spitz nevi tend to be seen particularly in the centre of the lesion whereas in an amelanotic melanoma they are more often located at the periphery but this is not a good discriminator to use in separating the two lesions!

The table below is taken from Atlas of Dermoscopy by Ash Marghoob and others published by Taylor and Francis Year Book group. It is an excellent schematic summary of vascular patterns.

Harald Kittler has tried to rationalise much of the terminology we use in dermatoscopy descriptions. His approach to describing vessels and vascular patterns is illustrated in this blog www.haraldsalgorithm.blogspot.com. This section and the introductory section of the blog by Dr Cliff Rosendahl should explain his ideas.
The following article from Dermatopathology Practical and Conceptual also illustrates Harald's approach.



Nodular BCC I go back to nodular Bcc because in day to day work the clearly focussed arborising vessels are an excellent confirmatory dermatoscopic feature of your clinical suspicions. Mind you a good nodular bcc often has telangiectatic vessels running across the surface visible clinically!
It is also easy to see the difference between comma vessels of dermal nevi and the arborising vessels of Bcc. Clinically it can be very difficult to differentiate a dermal nevus and a small Bcc.
View this dermal nevus in Dermoscopy Atlas



This lesion was a BCC but it would be difficult to make the diagnosis without the dermoscopy. It appears to be a keratinising tumour but when part of the scale is removed the arborising vessels of a BCC become visible.
View this case in the Blog courtesy of DrJean Yves Gourhant



Clear cell acanthoma has a characteristic pattern of vessels called a string of pearls. It is basically a set of linear red dots arranged like a string of red pearls. Only part of the lesion may show this feature. Clinically the lesion is pink or red reflecting its vascularity and smoothe surface.

View this excellent example from Dr Alan Cameron in the Blog

Also look at this discussion of differentiating the dermatoscopic features of Clear cell acanthoma and psoriasis.



This case courtesy of Dr Stelios Minas shows corkscrew vessels in an amelanotic melanoma arising in a congenital nevus. The congenital nevus shows comma vessels. The latter are also seen in dermal nevi.
When this case was shown on the blog many people thought these were arborising vessels of a BCC but when did you last see a BCC arising in a congenital nevus?

View this other blog image of corkscrew vessels.

Then view the case

View this other blog image of corkscrew vessels.

Then view the case

Insert Image Here of Pigmented purpuric dermatosis

One can also use vessels to diagnose conditions such as pigmented purpuric dermatosis particularly on the lower legs. These will show small dot like pinpoint vessels overlying the coarser reticular dermal vessels.

Insert image here of Striae

Vessels in a rope and ladder type pattern can be seen in scars particularly in abdominal striae.



Eccrine poroma is a tumour derived from the acrosyringium of the sweat gland. It is another possibility in the differential diagnosis of pink or red exophytic papules or nodules. The lesions are typically found on the palms or soles because these are sites where you have a lot of sweat glands. Ocassionally these lesions can be slightly pigmented making them look even more like amelanotic melanomas!
Their vascular pattern though is different with more hairpin like vessels rather than the dot and linear irregular vessels of melanoma or the string of pearls of clear cell acanthomas.

The case below is courtesy of Dr Jean-Yves Gourhant and he supplied the following references and comments.

Altamura D, Piccolo D, Lozzi GP, Peris K.
Eccrine poroma in an unusual site: a clinical and dermoscopic simulator of amelanotic melanoma.
J Am Acad Dermatol. 2005 Sep;53(3):539-41.

Nicolino R, Zalaudek I, Ferrara G, Annese P, Giorgio CM, Moscarella E, Sgambato A, Argenziano G.
Dermoscopy of eccrine poroma.
Dermatology. 2007;215(2):160-3.

In the 1st one, the EP was located on the pubis, and dermoscopy showed atypical vascular structures: milky red areas, irregular vessels, dotted vessels. The overall aspect oriented towards an AMM. I have only the abstract of the 2nd.
In my case, the macro view is not really worrysome. The dermoscopy is "unusual", mostly made of long hairpin vessels, and milky red areas.

I excised a bit more than one year ago another EP: a young patient, on the forehead! And once more there were unusual vascular features. I copy the picture at the end of the post.It is shown below.

View this case in the Blog



The other eccrine poroma from Dr Jean -Yves Gourhant mentioned above



This is an excellent case showing glomerular vessels in Bowen's disease courtesy of Dr Greg Canning.

This is an excellent Blog presentation by Cliff Rosendahl looking at several lesions with vascular features

I think it would be useful to again go over Alan Cameron's PDF presentation of Harald Kittler's terminology of vascular features. There are some good images in this presentation and you should appreciate the features better now that you have completed this module.
Download it here

Module 9.1 Facial Pigmented Lesions and Lesions of Palms, Soles and Nails

Authors Dr Alex Chamberlain and Dr Ian McColl
Contact Alex regarding the module on Lesions of the palms,soles and feet or Ian on the module on Facial pigmented lesions or to send any additional images you have which would improve the module.
If you would like an online teleconference on the Facial Pigmented Lesions in which we can talk while you see my desktop and mouse then contact imccoll@ozemail.com.au for instructions.

Module 9.1 will deal with facial pigmented lesions. Additional text and images for this module can be viewed as a Powerpoint presentation by clicking here.

Facial Pigmented Lesions

The diagnosis and management of facial pigmented lesions is one of the major problems in dermoscopy in Australian Dermatology. Because of our chronic sun exposure freckles, lentigines, solar lentigo,pigmented solar keratoses, lentigo maligna, lentigo maligna melanoma and invasive melanoma are all commonly seen. Add in pigmented BCCs, pigmented SCCs and pigmented solar keratoses and you have a lot of potential lesions to choose from!
Nonetheless, if your pigmented lesion is a light brown uniform colour then it is likely to be a simple solar lentigo, which is a keratinocytic lesion with increased melanin in the keratin cells, rather than a tumour of melanocytes. The production of melanin in these lesions becomes autonomous as against a freckle where it will fade in the winter months whereas solar lentigo will continue to produce pigment year round independent of sun exposure. However if one of these lesions starts to develop varying areas of pigmentation, where it is darker in some spots than others, then you should be clinically suspicious the lesion may be a lentigo maligna.


The problem then is assessing what sort of biopsy to do. Punch biopsies can be notoriously fickle in showing you relevant pathology and you may get a benign histology when really it is an early lentigo maligna. Hence the best idea is an incisional biopsy through the darker areas to take this part of the lesion out if it is too big to take it all out at once. Another approach is to take a shave biopsy which will give the Pathologist a reasonable bit of tissue to look at but it often fails to give an adequate idea of the depth or thickness of a lesion and hence fails to give you the correct information for your excision margins.


The other common lesions seen on the face are seborrhoeic keratoses. These usually are light brown in colour but of course can be any colour all the way through to black. They are typically seen at the scalp margin and have a rough, slightly keratotic surface, which is best experienced by scraping with the finger nail. However early seborrhoeic keratoses can be quite flat and can be dark as well. When you look at them with the dermatoscope you can see what appears to be a netlike pattern. The compounding problem on the face is that you have openings of grease glands and hair follicles. Histologically on the face you have flattened rete ridges and the openings of these hair follicles and sebaceous glands look like a pseudo network. Early seborrhoeic keratoses may show features of milia or crypts and the edges are usually quite sharp. However they may show a moth eaten picture where there is a scalloped edge. They may show other structures called fingerprints where there appears to be a network of straight lines lined up together. These can also be seen in solar lentigos, which are also keratinocytic lesions rather than tumours of abnormal melanocytes.

The early lentigo maligna will show some asymmetrical pigmentation around the opening of follicles on the face and as this expands it will join up with adjacent areas of perifollicular pigmentation and structures called rhomboid structures can be seen. If the pigmentation extends further then a complete homogenous area of darker pigmentation will occur and if the lesion subsequently develops into a lentigo maligna melanoma with invasion of cells down into the dermis, then colours such as blue and brown will become more prominent. The histological hallmark of a lentigo maligna is that there is a lentiginous or linear proliferation of melanocytes along the dermo epidermal junction rather than nests of melanocytes forming at the dermo epidermal junction. Once you start to have nesting it is more likely to be a lentigo maligna melanoma and the prognosis of this lesion is the same as any other melanoma of comparable thickness. So if you are clinically suspicious because of varying pigmentation in the larger pigmented lesion and you have some asymmetrical perifollicular pigmentation or rhomboid structures or annular granular structures on dermoscopy, then it is likely to be a lentigo maligna and either excisional, incisional or a shave biopsy is necessary to confirm the diagnosis. These lesions then have to be excised with at least 5mm margins but one of the problems again is that atypical melanocytes can often extend a bit further than you can see clinically and some authorities would recommend 10mm margins for adequate excision of these lesions.

Usually a lentigo maligna will show some slate grey dots and globules. Slate grey dots are due to melanin in melanophages in the dermis and usually represent some degree of regression. These are also a feature of other lichenoid reactions particularly a lichenoid keratosis or lichen planus like keratosis seen in sun exposed areas such as the face and the back of the hands. The characteristic clinical feature of these lesions is the sudden inflammation around a benign pre existing pigmented lesion.

This dermoscopy image is of an extensive lentigo maligna that has been growing for 16 years. Recently it became raised in the centre. Histology taken as a punch across three areas showed lentigo maligna melanoma ranging from 0.6mm thickness on the patient's right side of the lesion , through 1.2mms in the centre and melanoma in situ at the far left. The dermoscopy shows the blue colour of dermal melanin, perifollicular pigmentation and a disrupted network. This case can be seen in the Skin Cancer Blog.



Lentigo maligna is melanoma in situ. It grows very slowly and the atypical melanocytes proliferate in a linear fashion along the dermo epidermal junction. It therefore has no real thickness and will fail to reach lymphatics or vessels to spread systemically. Schiffner and others developed a progression model for lentigo maligna that began with dark grey dots arround the hair follicle openings, with subsequent enlargement causing asymmetrical perifollicular pigmentation. As this increased the areas merged and rhomboidal structures were formed. Further progression gave homogeneous areas of pigmentation, some showing the follicular openings within and some having them completely obliterated. In lentigo maligna cells proliferate down the hair follicle but remain confined within it and do not spread to lymphatics.
The main clinical differential diagnoses are flat dark seborrhoeic keratoses or solar lentigos.The latter will have a more uniform colour, fingerprint like areas and a scalloped moth eaten edge. Seborrhoeic keratoses will have similar features plus milia, comedo openings and fissures and crypts.

Surgical excision of lentigo maligna on the face is difficult because of the field change in the melanocytes that has occurred and the difficulty in establishing the edge of the lesion. Margins of 5mm are suggested but practical experience suggests 10mm margins are more appropriate. However this can mean a significant cosmetic defect on the face. Any invasive component should be adequately excised initially with further surgery later for any lentigo maligna recurrences. Hence it is obviously best to diagnose these lesions when they are small and adequately excise them at that stage.
Other therapies used in treating lentigo maligna include cryotherapy, imiquimod, azelaic acid and radiotherapy if the patient is unable or unwilling to have extensive surgery. In the case below it is important to make sure the condition does not spread to the eyelid as it becomes very difficult to clear it from this site.

This case was initially thought to be a seborrhoeic keratosis and followed by her GP for several years until it became obvious the features were those of a lentigo maligna with a probable invasive component developing. The case can be viewed in the Skin Cancer Blog.



The Ink Spot Lentigo can be very dark and may clinically look like a lentigo maligna. It tends to affect fair skinned individuals with skin types 1 and 2. It has a prominent network but it is often broken up. There may be a homogeneous central black area. The black pigmented network is constant throughout the lesion though the network can vary in thickness. It usually ends abruptly at the edges.
This is a keratinocytic lesion with increased melanin in the keratinocytes. It does not have melanocytic hyperplasia like a lentigo maligna. It does not have any malignant potential.

In the case below the lesion arose on the nose after a sunburn. It was removed for cosmetic reasons by shaving it off. The case may be viewed in the Skin Cancer Blog.



The Pigmented Solar Keratosis is rough to the touch, spread over the skin surface and pigmented. As such it looks like a seborrhoeic keratosis. It is usually seen on the face. Generally they are better diagnosed clinically than dermoscopically because they have little in the way of distinguishing features.They have an irregularly pigmented pseudo network pattern on the face but the colour is usually uniform. Annular granular structures can also be found. In lentigo maligna the network is genuine and irregular with greater colour variation. In seborrhoeic keratoses you should have milia like cysts and comedo structures.
If pigmented solar keratoses are not recognised and treated they may develope into pigmented SCC in situ and become quite large.

In the case below the keratosis occupies a reasonable area of the nasal tip. It is a slate grey colour and can be felt to be rough if scratched with your fingernail. Dermatoscopically it shows some perifollicular pigmentation and could be confused with an early lentigo maligna but the clinical picture and the rough surface is against that diagnosis.



The seborrhoeic keratosis is not a difficult lesion to diagnose clinically when it shows its typical verrucous surface but the early flat dark lesion is more difficult and may just be smoothe or greasy. In moist areas they can loose their scales. A compounding problem of seborrhoeic keratoses on the face is the pseudonetwork found there leading you to call the lesion melanocytic. However if you see milia, crypts and fissures you can avoid that mistake. The very earliest flat seborrhoeic keratoses may just show finger printing and moth eaten edges which are not specific and can just as easily be solar lentigenes. A few milia can occasionally be seen in melanocytic nevi and rarely even in melanoma. Very dark comedo like openings can simulate globules of melanocytic lesions. Hairpin like vessels are only ever seen in pinkish seborrhoeic keratoses in my experience.

This patient has many of the features you would want to make a diagnosis of seborrhoeic keratosis. However there is a case in the powerpoint presentation of a shaved seborrhoeic keratosis on the face reappearing as a lentigo maligna! It was misdiagnosed initially!



Facial pigmentation can sometimes be quite unusual and the dermatoscopic picture can be unlike anything you have ever seen before. In these cases think of drugs or some other exogenous pigment such as silver causing agyria. This stippled pigmentation is due to minocycline taken for rosacea in high doses of 200mgs a day for more than two years. Even when the drug is stopped it will take several years for macrophages in the skin to slowly break this down and transport it away.



Pigmented Bowen's disease on the face usually developes from a pre existing pigmented solar keratosis. Hence it is part of the differential diagnosis of lentigo maligna on the face. They can both show asymmetric pigmented follicles,annular granular pattern and rhomboidal structures. Clinically pigmented Bowen's disease feels rough to the touch whereas lentigo maligna is smoothe.

This lesion below is quite extensive for a pigmented solar keratosis and on histology showed pigmented Bowen's disease. It did not show the glomerular vessels you would often see in Bowen's disease but a case in the Powerpoint will demonstrate these. This lesion was treated with topical imiquimod cream 5x a week for 6 weeks and cleared nicely. The case can be viewed on the Skin Cancer Blog.



Pigmented BCCs can also be found on the face but generally are not difficult to diagnose. Usually they are partially pigmented but some can look very blue. The dermatoscope will show the lack of a pigment network , blue grey ovoid nests, sometimes globules described as leaf like areas and arborising telangiectasia. Pigmented BCCs behave just like BCCs elsewhere. They are all of the nodular or cystic type on histopathology.



Remember there are other unusual pigmented lesions on the face. This man presented with the sudden onset of a blue papule on his eyelid. The dermoscopy was decidedly blue like a blue nevus but the lesion was actually due to bleeding into an apocrine cyst. The lesion was resolved by incising the cyst. If the lining is left it can recur but some inflammation often causes the cyst walls to adhere together and scar.



Other blue black lesions seen on the face include venous hemangiomas. Usually they are solitary and easily diagnosed with pressure causing rapid emptying with slow filling. Occasionally one may thrombose and fail to empty. However the vasdcular lacunae should still be visible with the dermatoscope.

When you have completed this section view a Powerpoint Presentation with additional images and conditions by clicking here.
After that try the test images in Image Diagnosis.Filter for Module 9.

Module 9.2 Facial Pigmented Lesions and Lesions of Palms, Soles and Nails

Acral Lesions

Acral lentiginous melanoma can be difficult to diagnose both clinically and dermatoscopically. Benign acral nevi occur in about 10% of the population and hence if you are examining a patient properly you will be regularly called upon to express an opinion on an acral pigmented lesion. Biopsy in this area is not easy. It is painful to inject the local anaesthetic and the actual histological interpretation on acral nevi is fraught with difficulties because it is not uncommon to see single melanocytes up high in the epidermis that may lead an inexperienced pathologist to make the call of an in situ melanoma.

Much of the problem in interpreting acral lesions is due to the peculiar anatomical characteristics of these areas. Skin on the sole of the foot or palm of the hand is characterised by dermatoglyphics which are made up of the parallel arrangement of the surface skin markings which may either run straight or in whorls. These markings are described as having ridges and furrows. The ridges are raised and the furrows are sunken with the opening of eccrine ducts occurring in the centre of the ridges. When tissue sections are cut perpendicular to the parallel skin markings you get two distinctive epidermal rete ridge patterns. The one situated under the surface ridge is called the crista profunda intermedia. The eccrine duct passes through this ridge or at least the intraepidermal component of it. This is known as the acrosyringium. The other type of rete ridge is situated under the surface furrow and it is called the crista profunda limitans. It does not have the eccrine duct running through it. Remember that these eccrine ducts open in the centre of the surface ridges and if you see them in dermoscopy it helps to separate the ridges from the furrows. Generally the ridges are broader than the furrows. These anatomical features are illustrated in the image below.




There are a variety of patterns seen when you examine acral pigmented lesions. Benign pigmented nevi show three typical dermatoscopic patterns namely the parallel furrow pattern, the lattice like pattern and the fibrillar pattern. Following on from the anatomical description above, the pigment nests will be confined to the crista profunda limitans that underlie the furrows or sulci. The lattice like pattern is a variant of the parallel furrow pattern in which most of the pigment is confined to the furrows but there are some vertical elements crossing the ridges. The fibrillar pattern is another benign variant in which there is both a thick and a thin type. The thick type is arranged in a mesh like pattern running across both the ridges and the furrows. These features are due to columns of pigment in the stratum corneum of the epidermis in which melanin granules are distributed along an oblique arrangement. With dermoscopy we view the melanin underneath in a vertical direction so if something is oblique it will look like a slanted line. The density and thickness of it depends on the amount of melanin deposited. Some melanocytic nevi will show combinations of both a parallel furrow pattern and a fibrillar pattern. There are also some rarer benign variants particularly seen in the Japanese that are called the dotted or globular pattern, a reticulated pattern and a diffuse pattern. This diffuse pattern made up of homogenous brown pigmentation is sometimes seen in benign nevi with a prominent intradermal component. Many of these acral nevi are congenital nevi.

The image below shows these patterns in a schematic form but we will show you some clinical examples further on in this module.



This slide shows the relative frequency of these acral patterns that we have been describing. The parallel furrow and lattice pattern make up about 85% of the patterns you will see on the palms and about 60% of patterns on the soles. On the soles the atypical and fibrillar patterns are more frequent.



It is interesting to look at the distribution on the sole of the foot of these patterns. Notice that the lattice type pattern is mainly seen on the non weight bearing areas of the foot whereas the fibrillar and parallel furrow pattern mainly occurs on the weight bearing areas.



Some of these patterns can be changed just by applying lateral pressure to the lesion. Jonathon Bowling published on this feature in Clinical Experimental Dermatology in 2006.



The Diagnosis of an Acral Melanoma

The acral lentiginous melanoma where there is a spread of cells occurring at the dermoepidermal junction typically presents as a parallel ridge pattern of pigmentation or PRP pattern. This pattern is highly significant of melanoma with a sensitivity of 86% and a specificity of 99%. In early in situ lesions the pigment pattern is uniform throughout the entire lesion, but in later invasive lesions the pattern may just be focally detected and the colour variation will be more prominent. Why in early phases of melanoma the melanocytes should proliferate mainly in the crista profunda intermedia underlying the ridges is unknown. In early acral lentiginous lesions the pigmentation is often uniform but in later lesions it becomes multi component with various colours including a blue/grey tone. Occasionally more advanced acral lentiginous melanomas will show focal areas of a parallel furrow pattern, the lattice pattern and the fibrillar pattern but the important thing is that it is focal unlike a benign lesion in which one of these patterns will be predominant throughout the entire lesion.

The PRP or parallel ridge pattern can very rarely be seen in other acral pigmented lesions other than melanoma. For example it occurs in the Peutz-Jeghers’ syndrome and the Laugier-Hunziker’s syndrome but these conditions will be given away by the multiple pigmented macules on the lips and elsewhere on the body.



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Subcorneal haemorrhage or talon noir on the heel can show a pattern similar to the PRP pattern but if you look at them carefully they show characteristic pebbles on the ridges feature made up of reddish black pebble like pigmentation with smooth edges arranged along the ridges themselves.



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Module 9.3 Facial Pigmented Lesions and Lesions of Palms, Soles and Nails

In a lesion that may show both furrow and ridge pigmentation, always look at the outside of the lesion and see what the predominant pattern is there. If this is a parallel furrow pattern at the periphery, then irrespective of the central ridge pigmentation it is likely to be a benign lesion.



In a lesion that may show both furrow and ridge pigmentation, always look at the outside of the lesion and see what the predominant pattern is there. If this is a parallel furrow pattern at the periphery, then irrespective of the central ridge pigmentation it is likely to be a benign lesion.

View this case in the Blog.



Nail Pigmentation

See Article on nail pigmentation

Dermoscopy can be useful in analysing the cause of sub ungual pigmentation. The commonest clinical situations are to distinguish blood due to trauma from a subungual melanoma. Other situations include a pigmented dermatophyte infection of the nail and also the sharply defined dark linear streak on a nail seen in children or in an adult. Often the history of a linear streak present from birth or early chidhood will ease your concern but even a benign nevus of the nail matrix can potentially become malignant.
Lets look at each of these scenarios.



Pigmented Nail Lesions

Pigmentation of nails can occur for a variety of reasons including nevi, melanoma, subungual haemorrhage, lentigo, drug induced pigmentation and some normal ethnic nail pigmentation. The commonest cause of sudden onset nail pigmentation is a subungual haemorrhage. Classically this will show under the dermatoscope as a purplish red pigmentation with a rounded proximal edge perhaps with some drops of blood but with a filamentous like distal edge. The colour can vary from red to purple to black but it usually grows out from the base and there is no involvement of the cuticle.
A subungual blue nevus can be difficult to differentiate from a subungual haemorrhage. Needless to say if the lesion has been there for a considerable period of time without any growing out distally then it is much more likely to be a blue nevus. The blue nevus typically has a rounded distal edge without any of the filamentous outgrowths that you would expect from a subungual haemorrhage.



A benign pigmented lesion in the nail matrix will give rise to a well defined, uniform coloured pigmented band of the nail occurring from a relatively early age. Under the dermatoscope the pigmented area will be seen to be made up of parallel pigmented lines but these are evenly sized and spaced.

In contradistinction if you have a melanoma of the nail matrix the pigmented band will be relatively new or if there is a pre-existing one it will have changed significantly. There may be variation in colour and under the dermatoscope the longitudinal bands are of varying sizes and the spacing is not uniform.

View this case in the Blog



Note the pseudo Hutchison’s sign is the visibility of pigmentation through a translucent cuticle. This is seen particularly in a nevus originating in the nail matrix. Obviously any apparent involvement of the cuticle is within the confines of the lesion passing under it. There is no spread outside this line. With a subungual melanoma as the lesion progresses the whole nail plate can be involved and it becomes eroded and broken and the pigmentation will extend beyond the confines of the nail bed and involves some of the periungual skin. This is shown in the image illustrated below.



If you are going to biopsy linear nail pigmentation, generally the area to take the biopsy is from the nail matrix. This involves reflecting the posterior nail fold and using a 2mm or 3mm punch biopsy of the pigmented nail matrix. This area should be sutured if at all possible to prevent a linear defect of the nail subsequently developing. Generally though a 2mm punch biopsy will heal on its own without problems. If a nevus is causing the pigmentation then excision of this nevus in spite of attempted suturing will probably leave a linear defect in the nail. Therefore most benign subungual nevi are not excised.



Rarely you can get amelanotic melanoma involving the nail matrix or the nail bed. This is obviously a difficult diagnosis to make. Generally there is disruption of the overlying nail itself with separation from the nail bed. When this occurs the most likely lesion is a squamous cell carcinoma of the nail plate but melanoma always has to be considered. Other potential diagnosis are pyogenic granuloma and inflammatory nail processes. You essentially have to biopsy the nail bed having removed the overlying nail after doing a ring block to make the diagnosis of a nail bed problem or the nail matrix underneath the posterior nail fold for a matrix derived lesion.

The case below can be reviewed in the Blog. It is courtesy of Dr Jean-Yves Gourhant.



Lentigines on the nail bed generally present with a grey pigmentation in the background and superimposed on this are really quite thin parallel longitudinal greyish lines. This pattern is also a feature of drug induced pigmentation and some ethnic pigmentation. Generally of course several nails are involved rather than one. The causes of drug induced pigmentation of the nail include Minocycline, hydroxyurea, acyclovir and chlorpromazine. Generally more than one nail is affected. Rarely Bowen’s disease of the nail can be pigmented but the pigmentation is usually diffuse, non structured and is associated with subungual hyperkeratosis.

The case below can be reviewed in the Blog. It is courtesy of Dr Jean-Yves Gourhant.