Giant keratoacanthoma of the upper extremity treated with mohs micrographic surgery: a case report and review of current treatment modalities.

Keratoacanthomas are fast-growing, solitary, cutaneous neoplasms that usually show spontaneous regression. The development of giant variants and aggressive behavior have been described. Clinically, a keratoacanthoma larger than 20 to 30mm is classified as a giant keratoacanthoma. A major challenge in dealing with these neoplasms is the difficulty of clinically and histologically differentiating them from squamous cell carcinoma. The authors report a practical approach using Mohs micrographic surgery for evaluation of large tumors. With this method, the lateral margins are evaluated and cleared prior to excision of the bulk of the tumor. The authors also describe alternative therapies for giant keratoacanthomas and present a case of a 61-year-old woman with a rapidly growing tumor on her left arm. Skin biopsy was consistent with a well-differentiated squamous cell carcinoma with focal features of a keratoacanthoma. The patient underwent Mohs micrographic surgery using the described approach, and no recurrence has been noted in four years. Surgical excision remains the treatment of choice for giant keratoacanthomas. Mohs micrographic surgery is a logical treatment option for giant keratoacanthomas. This case illustrates a useful approach that may prove valuable when treating large specimens during Mohs micrographic surgery.