A 65‐year‐old woman presented with multiple subungal lesions for the past forty years. These were associated with increasing pain with growth, relieved only by destruction. They were treated as subungal warts by electrocautery and surgical excision. A biopsy of one lesion was interpreted as squamous cell carcinoma with subsequent partial amputation of the affected digit. She continued to develop painful subungal growths involving all her fingers, requiring repeated surgeries. On physical examination, subungal tumors associated with hyperkeratosis and erythema of the nail bed were found on the right thumb and ring finger. Subungal hyperkeratosis involved all other fingers. On histological examination, there was marked dyskeratosis with features of subungal keratoacanthoma or squamous cell carcinoma. This patient has a history of incontinentia pigmenti (IP) since childhood and she has three daughters with IP. We report a case of painful subungal dyskeratotic tumors in IP, considered as keratoacanthomas by some, as they grow rapidly and may demonstrate spontaneous resolution, albeit rarely. The distinguishing features of subungal tumor in IP are its occurrence in young women with multiple lesions and signs of IP, and its tendency to erupt persistently over a course of several years.
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