Keratoacanthoma as a postoperative complication of skin cancer excision

Background Keratoacanthomas usually occur spontaneously as a single rapidly growing tumor on sun-exposed skin. Multiple keratoacanthomas are rarely seen. Keratoacanthomas may also develop after trauma, laser resurfacing, radiation therapy, and at the donor site after skin grafting. Objective We report 6 cases of keratoacanthomas that developed in and around healing and healed surgical sites after treatment of skin cancer. These tumors developed 1 to 3 months after surgery and were sometimes multiple. Methods We performed follow-up examinations of patients' wounds after the treatment of skin cancer. Histological examination of nodules developing in the margins of healing wound sites and in the scars of healed wound sites after Mohs micrographic surgery revealed keratoacanthomas. Results The tumors presented as a rapidly growing nodule or nodules, with the typical morphology and pathology of keratoacanthoma. One patient developed multiple keratoacanthomas at surgical and nonsurgical sites. These nodules were treated by a combination of excision, curettage and electrodesiccation, and oral isotretinoin, 4 mg/d. Conclusion Keratoacanthoma must be considered in the differential diagnosis of a rapidly growing nodule within or around the surgical site after skin cancer surgery.