(Dr Wynn Hlaing)
READING
1. Handbook of Dermoscopy [J. Malvehy,S.Puig,RP. Braun,AA. Marghoob & AW. Kopf ;Reprint 2006].
2. An Atlas of Surface Microscopy of Pigmented Skin Lesions:Dermoscopy[2 nd Edition SW. Menzies,KA. Crotty,C.Ingvar & WH.McCarthy].
3. Color Atlas of Melanocytic Lesions of the Skin [HP.Soyer,G.Argenziano,R.Hofmann-Wellenhof & R.Johr;2007].
Topics.
Lesions with regression: Melanocytic nevus,Clark nevus,Lichen Planus-like Keratosis (LPLK) and Melanoma; Mucosal Lesions, Collision Lesions, Blue Lesions, Spitzoid Lesions, Ink-spot Lentigo, Atypical-Mole or Dysplastic Nevus Syndrome and Digital follow up of melanocytic lesions – Short-term and Long-term monitoring.
Introduction.
This module will introduce the definitions/descriptions of above mentioned topics and to be able to detect and differentiate the lesions which are presented with dermoscopic features of regression , lesions with uncommon presentations and lesions on mucosal sites.
LESIONS WITH REGRESSION.
Regression in a lesion may present with blue-gray colour,blue or white colour and combined blue /white colouration.White colour means bony white or whiter than the surrounding skin .It represents orthokeratosis of stratum corneum and fibrosis in the upper dermis.Blue/grey colour may present as ‘peppering’or ‘grey-blue veil .It represents heavy pigmentation of melanocytes and melanophages in the papillary dermis.
Blue-white veil is an irregular ,indistinct,confluent blue pigmentation with overlying white ground glass haze.Blue-white veil cannot occupy the whole lesion and usually corresponds to papular or nodular portion of the lesion.Blue-white veil cannot be associated with multiple red-blue lacunae seen in haemangiomas.It should also be differentiated from discrete ovoid nests seen in pigmented basal cell carcinomas.
Nowadays more usuage of the term blue-white structures has taken over the terminology of blue white veil.Blue white structures are seen in Clark nevus,Spitz nevus and melanoma.It is regarded as high risk criteria.As a general rule,any blue or white structure in a flat part of the lesion corresponds to regression and the blue white structures in a nodular or palpable part is a blue-white veil which corresponds to dermal infiltrate or invasion.
Regression can be immunogenic,physiologic,iatrogenic and pathologic.Examples will be given by showing Sutton or halo nevus[physiologic],dysplastic nevus,LPLK and melanoma[pathologic].Regression should not be mistaken with hypopigmentation.According to Ferrara et al.features of regression in melanocytic lesions might lead to an interobserver disagreement on diagnosis from a dermoscopic and even histopathological point of view.For example,completely regressed halo nevus can be very difficult to differentiate from completely regressed melanoma.
LPLK - Immunologically mediated regression of the existing lesion-i.e seborrheic keratosis.Subtypes include classic,atypical,bullous,interface and atrophic lesions.
It was described simultaneously in 1966 by Lumpkin and Helwig as ‘soiltary lichen planus’ and by Shapiro and Ackerman as ‘solitary lichen planus-like keratosis’.Both authors underlined the histopathological pattern of lichenoid reaction.
Some authors stated that in benign nevi,regression structures are usually mild[less than 25% of the entire lesion].If in doubt, always get a second dermoscopic opinion from more experienced colleague and try to make patho-dermoscopic correlation.
Uncommonly,primary melanoma may undergo complete regression and its recognition usually follows development of metastatic melanoma and search for primary melanoma.
It is important to note that regression is seen in 46% of thin ,32% of intermediate and 9% of thick primary melanomas.
Also important to note that peppering (granules) in inflammed,regressive seborrheic keratosis(LPLK or BLK-benign lichenoid keratosis) is likely to be widespread and coarse,where as in cutaneous melanoma it tends to be fine and multifocal.
Guide principle when analyzing the lesion with regression.
The more regression
The more asymmetry
The more colours
Benign ------------------------------------------------->> Malignant
DIAGNOSTIC AND MANAGEMENT ALGORITHM OF LESIONS WITH REGRESSION. [AFTER I.ZALAUDEK et al ; BJD-2004;150,65-71]
Example: Clark Nevus. Clark nevus which shows blue-white structures ,irregular streaks and blotches. (Image courtesy of Dr Alan Cameron)
Example: Marked regression.Clark Nevus with white structures (colour) which is more marked than the surrounding skin.You can also see this type of regression in traumatized nevus(iatrogenic).In trauma- related scenario,white structures will show lack of multiple small gray dots.If you see this extent of regression in a lesion ,biopsy is mandatory to rule out melanoma. (Image courtesy of Dr Peter Bourne)
Example: Lichen Planus-like Keratosis.(Immunogenic)
Peppering : Brownish gray and bluish gray,localized or diffuse coarse granules.They are tiny granules with approximate size of 0.01-0.02 mm diameter.No specific features of melanocytic lesion criteria was noted
Example : Teenager with nevi on the back with various degrees of regression.He is a student who works as ‘surf live-saver’ on weekends.His skin phototype is Fitzpatrick I-II.This nevus has marked regression(blue&white structures more than 50% of the lesion) and excional biopsy was done to exclude a melanoma.
MUCOSAL LESIONS.
Although pigmented lesions in these mucosal areas are not uncommon, primary melanoma of mucosal sites such as oral cavity,ocular, vulva,vagina,anorectum and nasal cavity are rare and usually diagnosed late with subsequent poor prognosis.They often share clinical and histopathological features of acral melanomas.The most common cell type making up these lesions is a pleomorphic spindle and dendritic melanocytes.
In our Australian society of multi-ethnicity and multi- culturism,one needs to be aware of the preferred sites of melanoma in different races.Preferred sites for melanoma on the backs of males and lower limbs of females are particularly true in fair-skinned population.On the contrary,mucosal areas along with acral and subungual areas are preferred sites of melanoma in African,Asian and other dark-skinned races.There is not enough data in the medical literature to quote the incidence of mucosal melanomas in Indigenous Australians.
The number of plantar-palmer nevi increases with skin colour(H.Woolery-Lloyd).She also observed that,it may explain the higher incidence of acral melanomas in dark-skinned persons.
Genital lesions
Genital melanosis,melanocytic papule.
Genital melanoma.
Dermoscopic Features
Mucosal melanosis
1. structureless pattern mainly found in melanosis of vulva.
2. parallel pattern predilection to lips and penis.
3. reticular like pattern –areola
Characterized by pigmentation of basal keratinocytes with normal or slightly increased number of melanocytes.Melanocytic macule can mimic melanoma.When seeing on genitalia it could create concerns to the patient and the physician .
Oral or genital melanosis and melanocytic nevi arising in genital skin may create diagnostic difficulties .Clinically,lesions are often similar to those of melanoma in-situ being asymmetrical,poorly circumscribed and irregularly pigmented.Genital nevi can be located on the vulva,the penis and the perianal region.
Melanoma on genital areas can have polymorphous features like different colouration from reddish –brown and black.Along with atypical vascular pattern it can show features of acral melanomas.Dermoscopic examination and imaging can be difficult due to laxity of the skin in those areas.When examining and analyzing mucosal macules the examiner needs to realize that melanoma and melanosis can show overlapping features.
Genital lesions can be assosiated with certain medical disorders like LEOPARD ,LAMB,Peutz-Jegher,Laugier Hanziker and Ruvalcaba-Myhre-Smith syndromes.There is also a condition known as pseudolentiginous lesion which is due to zipper injury to the penis.
Important indication for the use of dermoscopy in oral and genital lesions is to identify suspicious areas for biopsy and to differentiate histopathologically melanoma from benign lesion.
Example : Labial melanotic macule of lower lip. Parallel and regular pigment formation indicates benign lesion.This case has been follow up six monthly.
Example: Venous lake of the lower lip.This is a benign lesion with homogenous red- blue colour.Emptying sign is demonstrable on this lesion.(Image courtesy of Dr Ian McColl)
Example : Genital melanotic macule , glans penis.He has no other pigmented lesions on the genital and other mucosal areas.
Example : Labial melanotic papule or melanosis.(Image courtesy of Dr Ian McColl)
COLLISION TUMOURS.
Definition : Presence of two or more different lesions,each showing its own specific dermoscopic features.
Synonyms : Colliding tumours ; Contigious tumours; Compound tumours.
Pathology: Common presentation would be combination of the followings- seborrheic keratosis,basal cell carcinoma,eccrine poroma,melanocytic nevus,hemangioma,intraepidermal carcinoma and melanoma.
Example : Collision tumour ; Basal cell carcinoma and seborrheic keratosis. Compound tumour depicting arborizing vessels ,multiple milia-like cysts,multiple blue gray globules and comedo-like openings. (Image courtesy of Dr Alan Cameron)
Example : Basal cell carcinoma with melanoma in-situ.Haemangioma is also noted.Collision tumours could elicit 'equivocal' features on dermoscopic examination.(Image courtesy of Dr Ben Cook)
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