A 90-year-old female developed a mass in her nose 3 months prior to consultation. Due to a rapid increase in size of the mass 2 months before presentation, she visited a local hospital and was referred to our department for squamous cell carcinoma. Around the dorsum of the nose, there was a mass（bottom surface, 45×35 mm；height, 30 mm）with a hard animal horn-like keratinous projection（cutaneous horn）in its superior portion. According to the criteria for resection of squamous cell carcinoma, the tumor was completely resected with a 5-mm margin. Based on the histopathological examination, a diagnosis of a keratoacanthoma with a cutaneous horn was made. The wound was closed using 2-stage full-thickness skin grafting. At present, 1 year and 5 months after the operation, neither postoperative complications nor recurrence has been observed. Keratoacanthoma with a cutaneous horn is markedly rare. Keratoacanthoma resembles squamous cell carcinoma both clinically and histopathologically, and requires careful differential diagnosis after complete resection.
