Solitary Nonhealing Noduloulcerative Lesion on Heel of Left Foot

Abstract

Acral lentiginous melanoma is the most common type of melanoma in skin of color. Other common types are superficial spreading (most common in white people), nodular and lentigo maligna. Mutations in BRAF, NRAS, MEK, ERK and wild-type KIT followed by dysregulated mitogen-activated protein kinase pathway are the underlying cause of acral variant. It mostly affects palm and soles of elderly people and runs an aggressive course with poor prognosis. Other common sites are fingers, toes and subungual area. Irregular blue-black macules of more than 7 mm diameter turning into plaques with or without ulcer is the usual clinical course. Tender nodules and exophytic lesions may also develop over time. Histopathology of classical lesions show poorly circumscribed, noncohesive nests of melanocytes located parallel to the epidermis. Thick and long dendrites reaching up to upper layers of epidermis and increased number of melanocytes with large nuclei favors malignancy. Dermoscopy helps in early and accurate diagnosis whose important features are: parallel ridge pattern, asymmetry of color and structure, blue gray structures and linear and haphazard distribution of acrosyringia. An elderly male presented with single, tender bluish-black plaque with small ulcer on left sole for past 2 years. Acral lentiginous melanoma was our provisional diagnosis and acral junctional nevus, talon noir and ulcerated lichen planus were kept as differentials. Later 3 were ruled out by clinical and histopathologic examination. Management of acral lentiginous melanoma depends upon the staging of disease and sentinel lymph node biopsy. Surgical excision with 2–3 mm of safe margin, lymph nodes removal and immune check point inhibitors are the treatment options.