Squamous Cell Carcinoma Manifested as a Cutaneous Horn: A Key to Early Detection.

We report a case of squamous cell carcinoma manifested as a cutaneous horn. A 92-year-old man was referred to our department for evaluation of a 3-month history of a keratotic cutaneous horn on the left side of his neck. The height of the cutaneous horn was larger than the diameter of erythema at the base. Histopathological examination showed a hyperkeratotic horn developing over a mass of large atypical keratinocytes with large hyperchromatic and pleomorphic nuclei. Based on these findings, a diagnosis of squamous cell carcinoma was made. A recent study showed that cutaneous horns in association with invasive squamous cell carcinoma had a tendency to have less height than the diameter of the base. In our case, however, the height of the cutaneous horn was larger than the diameter of the base, indicating that invasive squamous cell carcinoma sometimes shows a cutaneous horn that is higher than the diameter of the base. Thus, clinical finding of erythema at the base of the cutaneous horn would be a reliable feature for early detection of squamous cell carcinoma.