Multiple cutaneous squamous cell carcinomas: primary carcinomas versus cutaneous metastasis.

Multiple squamous cell carcinoma (SCC) of the skin is an exceedingly rare entity. It has been reported in a few patients of psoriasis treated with oral psoralen therapy and UV radiation, immunodeficiency states, local intramuscular metastasis and cutaneous metastasis from vulvar SCC. We report the case of a 55-year-old man who reported with a painless non-healing warty growth on the lower back persisting for the last 2 years which was excised. Its histopathology proved it to be SCC with HPV changes. On examination, 4 similar lesions were found on the upper back; out of which 1 lesion exhibited marked dysplastic changes on histopathology, but without HPV changes. This case could be either multicentrically developed SCC due to HPV infection or cutaneous metastasis as carcinoma of unknown primary site i.e. metastasis occurring before primary tumor diagnosis.