Imiquimod for restoring local immunity in a renal transplant patient with persistent keratoacanthoma

Keratoacanthoma (KA), a cutaneous neoplasm histologically resembling squamous cell carcinoma, is characterized by rapid growth and common spontaneous regression. The regression depends on an individual's immune response. We are reporting a case of a 53-year-old man who presented with an ulcerated tumor, which had arisen as a nodular lesion 9 months earlier. This was localized on the the left thumb. The patient had undergone a kidney transplant after severe glomerulonephritis. Following the operation, he was treated with systemic immunosuppressive drugs and developed multiple non-melanoma skin cancers. The histology examination of biopsy specimens was consistent with keratoacanthoma and showed low-density chronic inflammatory cells. Our patient refused surgical excision, so we prescribed imiquimod 5 percent cream once daily for 5 days a week. After 6 weeks of treatment the lesion had regressed completely, yielding an excellent cosmetic result. Continued resolution was documented 3 years after treatment. The patient had no signs of graft rejection related to the imiquimod treatment.