Incontinentia pigmenti with painful subungual tumors: a two-generation study.

We report 2 cases of painful subungual dyskeratotic tumors occurring in a mother and daughter with incontinentia pigmenti (IP) as a late manifestation of the disease. Both patients had a history of similar lesions appearing over a period of years on the digits of both the hands and feet. Biopsy specimens of the current lesions were examined and compared with the previous material available on both patients. The current tumors and the earlier lesions (the latter of which had originally been given diagnoses that included squamous cell carcinoma, keratoacanthoma, and verruca vulgaris) showed similar histopathologic features that were consistent with the late (verrucous) stage of IP. To our knowledge, this is the first reported case of numerous subungual tumors in IP involving more than 1 generation in the same family; the first report of subungual tumors in IP to include a 16-year follow-up; and the first report of a probable recurrence of subungual tumors in IP at the same site of a previously surgically removed tumor.