Onychomatricoma on the fourth toenail: A rare tumor in a rare localization

Abstract

Onychomatricoma is a rare benign tumor of the nail matrix, characterized by finger-like projections that invade the nail plate. The fingernails of Caucasian women are most commonly affected. Because this tumor can easily mimic other more prevalent ungual diseases, it is crucial to be acquainted with its characteristic clinical and histopathologic features. The authors present a case of a 40-year-old man with an onychomatrichoma in the fourth left toenail, which was initially misdiagnosed and treated as onychomycosis.

Blue onychomatricoma: Blue discoloration of an onychomatricoma secondary to pigmented onychomycosis

“…[10][11][12][13][14][15] Not only can onychomatricoma be clinically misdiagnosed as onychomycosis, but concomitant fungi can also pose a histopathologic challenge. [16][17][18][19][20][21][22] This presents a diagnostic challenge as a nail clipping of an onychomatricoma may show onychomycosis, and a dermatopathologist unfamiliar with the other histopathologic features of a nail clipping from an onychomatricoma may miss the other diagnostic features. This can result in a lack of response despite appropriate antifungal therapy because an onychomatricoma may also be present (as in the case presented herein), and an excision is required to adequately remove the tumor.…”