Pseudo-fibrokeratoma of the nail apparatus with melanocytic pigmentation: a clue for diagnosing Bowen's disease.

Bowen's disease of the nail apparatus is a protean condition where pseudo-fibrokeratoma associated with melanocytic pigmentation was the clue leading to the clinical diagnosis. Migration of melanocytes into the superficial layers of the matrix epithelium may be associated with the extension of the epidermal tumoral process, without necessitating a real melanocytic hyperplasia.