Verrucous-Keratotic Malignant Melanoma (VKMM)

We report a patient with a verrucous keratotic variant of melanoma visiting the policlinic of Medical Institute of Ministry of Interior (MVR-Sofia), Department of Dermatology and Dermatologic surgery, with a keratotic verrucous lesion, located on the right thigh, partially deeply pigmented at upper right quadrant. The lesion had appeared three years ago before her presentation in the policlinic, and it had gradually enlarged and become darker in the last twelve months. The surface of the lesion was covered with thick hyperkeratotic lobules. The histologic evaluation revealed verrucous melanoma with a tumour thickness of 3 mm and Clark Level IV and focal ulceration. The tumour was staged as stage IIB (T3bN0M0). Sentinel lymph node biopsy was planned. Verrucous-keratotic forms of malignant melanoma occur more commonly in women and favour the extremities, but may be found on any anatomic site. Seventy-one percent of this melanoma type are situated on the upper and lower extremities. Although two-thirds of these neoplasms can be can be histologically graded according to the classification of Clark, one-third of these melanomas with marked verrucous hyperplasia and hyperkeratosis of the epidermis do not fit into his classification. Histological classification of patients with a verrucous keratotic type of melanoma may sometimes be extremely difficult. The marked papilliferous architecture of these lesions made an assessment of Breslow depth difficult. The presented case highlights the clinical existence and features of such benign-looking melanomas. It is therefore important for surgical pathologists to recognise this unusual variant of malignant melanoma, as it may be confused both clinically and pathologically with benign lesions.