A cutaneous horn is a conical projection above the surface of the skin that resembles a miniature horn. The horn is composed of compacted keratin. Cutaneous horns usually arise on sun-exposed skin but can occur even in sun-protected areas. Tenderness at the base of the lesion and lesions of larger size favor malignancy. Histologic examination is recommended to rule out malignant changes. The most common malignancy is squamous cell carcinoma. More than half of all cutaneous horns are benign.