A tangential biopsy performed on melanonychia may often be the superior biopsy technique in exacting an accurate diagnosis of suspect lesions, according to Nilton Di Chiacchio, M.D., department of dermatology, Hospital of Public Service, Sao Paulo.
Melanonychia is a longitudinal or transverse black- or brown- pigmented streak of the nail. Longitudinal melanonychias are of particular interest, Dr. Di Chiacchio says, because although they may be due to several causes (including onychomycosis, hematoma following ungula trauma or nonmelanoma melanocytic tumors), they may also be a sign of subungual melanoma or acral lentiginous melanoma.
"An accurate assessment of melanonychia can be very challenging, even for experienced clinicians, and failure to make an accurate diagnosis could be catastrophic. The main importance of melanonychias is that subungual melanoma may present itself as a pigmented streak of the nail, and therefore, accurate diagnosis of the suspect lesion is crucial," Dr. Di Chiacchio says.