The nail apparatus melanoma, also termed subungual melanoma, emanates from the nail matrix. Thus, it often initially presents as longitudinal melanonychia (LM). At that point, the lesion may only represent melanoma in situ. Later, destruction of the nail occurs and the melanoma may spread to the surrounding skin. Amelanotic subungual melanoma may occur [Cutis 2000;65;303].
Several clinical presentations occur including:
For LM, initially, there is a longitudinal streak along the nail. Over time, it darkens and widens. At some point, the lesion may thicken, and the pigment extend onto the proximal nail fold or onto the distal fingertip.
Pigmented or amelanotic nodules may develop in the nail bed. The process, when advanced, may destroy the nail entirely.
Hutchinson's sign--the extension of pigment onto the nail fold--is characteristic of melanoma. It is not pathognomonic, however, as pseudo-Hutchinson’s sign--hyperpigmentation in the absence of melanoma--does occur.
See also longitudinal melanonychia. Surgical excision by a trained specialist is in order.
Note: There is some evidence that nail apparatus melanomas that begin as LM have better survival outcomes [JAAD 2015;73;213].
Melanoma in situ's presenting predominantly and exclusively as longitudinal melanonychia.
Pigmentation extending onto the fingertip.
Thickening of the lesion and raising up of the nail.