Onychomatricoma, detail by detail

BACKGROUND: Onychomatricoma is a benign fibroepithelial tumor of the nail, first described in 1992 by Baran and Kint. The classic tetrad signs include thickening of the nail plate, xantonychia, transverse overcurvature of the nail plate and splinter hemorrhages. Some of these clinical features are also seen in onychomycosis, which leads to a misdiagnosis and delay in tumor detection. When nail plate is avulsed, a villous tumor emerging from the matrix is observed. The diagnosis is based on clinical findings, where dermatoscopy plays an important role, as do images such as magnetic resonance and ultrasound, but diagnosis is confirmed by histopathological findings. Complete surgical excision is the treatment of choice. CLINICAL CASE: A 56-year-old female patient with an initial diagnosis of onychomycosis, in who an onychomatricoma was suspected by clinical findings, dermoscopy and imaging, which was finally confirmed by histopathology. CONCLUSIONS: Onychomatricoma diagnosis is often delayed due to lack of knowledge about this disease, which sometimes causes an initial diagnosis of onychomycosis.