A cutaneous horn, medically known as cornu cutaneum, is an unusual skin growth that resembles a small animal horn or a hard, pointed spike. It forms when keratin, the protein found in hair, nails, and the outer layer of skin, accumulates and hardens. These growths can be white, yellowish, brown, or gray and often appear on sun-exposed areas, such as the face, ears, scalp, lips, and hands.

Although a cutaneous horn may look frightening, its appearance alone cannot reveal whether it is harmless. Some develop from benign skin conditions, including warts and seborrheic keratoses. Others may be linked to precancerous lesions, such as actinic keratosis, or even skin cancer, particularly squamous cell carcinoma. The condition beneath the horn’s base is therefore more important than the horn itself, and a dermatologist should examine any new growth.

Diagnosis may involve a skin examination and biopsy. Doctors can remove the growth and send a tissue sample for histopathological testing, which helps determine the underlying cause. Treatment depends on the diagnosis and may include surgical removal or other procedures. If precancerous or cancerous cells are discovered, additional treatment may be necessary.

Seek medical evaluation promptly if the growth increases in size, bleeds, becomes painful, develops an open sore, or changes in appearance. Never cut, burn, or remove a cutaneous horn at home, as this can cause injury and delay diagnosis. Although many are benign, professional examination is the safest way to rule out a serious condition and ensure appropriate treatment.