Pigmented Pre-malignant and Malignant Lesions of Skin with Special Reference to Atypical Presentations

Cutaneous melanocytic proliferations are diverse both morphologically as well as in their behavioural patterns. Both dermatologists and pathologists regularly encounter diagnostic dilemmas while interpreting such lesions.

To study all cutaneous premalignant and malignant lesions with respect to their clinical features and histopathological findings.

A retrospective study was done in the Department of Pathology over a period of 10 years (2004-14) on all the clinically pigmented lesions that were biopsied or excised. Out of these only premalignant and malignant melanocytic lesions were analysed with respect to their important clinical and histologic features. Immunohistochemistry was carried out using HMB-45 and S-100 where indicated.

A total of 338 skin cancers were reported, out of these 27, 7.9% were cutaneous malignant melanoma. Premalignant lesions were 33. The mean age for premalignant lesions and melanomas was 43 years and 50.7 years respectively with a male predominance in both groups. The sole of foot/ankle was the most common site of involvement by melanoma (n=8,29.6%) while sun exposed sites like face and scalp were common sites for development of premalignant lesions like dysplastic nevi, lentigo simplex, pigmented seborrheic keratosis and Bowens disease. One case presented as post-traumatic scar tissue which turned out to be desmoplastic melanoma. One case of amelanotic melanoma presented as recurrent painful penile ulcers. Both cases were confirmed on Immunohistochemistry.

All pigmented lesions should be regarded as tumours of uncertain malignant potential and treated with complete excision if possible with long term follow up.