Melanonychia striata refers to a pigmented (tan-brown-black) streak due to the presence of melanin in the nail plate and/or nail bed. The streak is caused by a focal increase of the number and/or function of normal appearing or of abnormal melanocytes. Pigmented bands, often involving multiple digits, are prevalent in individuals of the more deeply pigmented races and, in them, are considered to be “normal” in the vast majority of instances.
Among the causes of melanonychia striata are neoplasias including naevocytic naevi, atypical melanocytic hyperplasia, and acral lentiginous melanoma. A series of cases is presented to illustrate these oncological lesions. Until further knowledge is gained, surgical removal is recommended for those lesions resulting in melanonychia striata which fall into the neoplastic group.
It is concluded that much more study is required to determine the biological significance, natural history, and outcome of these periungual melanocytic neoplasias.