Benign or malignant cutaneous horn: Dermoscopy to rescue

Cornu-cutaneum, commonly known as a cutaneous horn, is a premalignant or malignant upright conical or cylindrical projection made of cornified material derived from basal keratinocytes. It usually grows on a base that has different etiologies, such as viral warts, actinic keratosis, keratoacanthoma, Bowen’s disease, seborrheic keratosis, basal cell carcinoma, Kaposi sarcoma, and squamous cell carcinoma. Dermoscopy of benign lesions comprises horn height greater than base diameter, the terrace phenomenon, less erythematous base, and less pain on palpation, and vice versa in the malignant ones.