Keratoacanthoma Presenting as a Cutaneous Horn of the Helix in an Elderly Man: A Case Report

A cutaneous horn is a clinical description of a conical projection of compacted keratin, and the lesion at its base may be benign, premalignant, or malignant.Keratoacanthoma is a keratinizing squamous lesion that may closely resemble squamous cell carcinoma, particularly on sun-exposed sites such as the auricle.We report the case of a 69-year-old man who was a non-smoker with a history of sun exposure and no relevant medical history and who presented with a slowly growing, asymptomatic mass of the left helix over several months.Examination revealed an exophytic lesion arising from the lateral border of the left helix with a long, curved, horn-like keratin projection, and no cervical lymphadenopathy.The differential diagnosis included squamous cell carcinoma, hypertrophic actinic keratosis, basal cell carcinoma, verruca vulgaris, and chondrodermatitis nodularis helicis.Wedge excision, including the underlying cartilage, with primary closure, was performed under general anesthesia.Histopathological examination showed a symmetric, cupshaped squamous proliferation with a central keratin-filled crater, prominent epidermal lips, and minimal atypia, without perineural or lymphovascular invasion; a dermatopathologist confirmed a completely excised keratoacanthoma.Recovery was uneventful, with no evidence of recurrence at six-week follow-up.A cutaneous horn of the ear should be completely excised, including its base, because the underlying lesion cannot be determined clinically.