Cutaneous horn masquerading as a seborrheic keratosis

PURPOSE: To report a case of seborrheic keratosis of the inner canthus presenting as cutaneous horn. OBSERVATION: A 67-year-old Asian male presented with a rod-shaped, pedunculated mass on his inner canthus. The mass grew rapidly and within 2 months measured 3.0 cm in length and 0.5 cm in diameter. It was completely excised and submitted for microscopic examination. The specimen consisted of a proliferation of basaloid cells arranged in a papillary pattern and associated with significant hyperkeratosis and parakeratosis of the overlying squamous epithelium. The pathological diagnosis was reported as seborrheic keratosis from the skin of the inner canthus. CONCLUSIONS AND IMPORTANCE: Seborrheic keratosis can develop into a rapidly expanding lesion such as a cutaneous horn and can be found in unusual locations. To our knowledge, this is the first report of a seborrheic keratosis from the skin of the inner canthus.