Brain metastasis from cutaneous squamous cell carcinoma coexistent with extramammary Paget's disease: A case report.

We report a case of cutaneous squamous cell carcinoma (CSCC), initially coexisting with invasive extramammary Paget's disease (EMPD), in the scrotum of an 84-year-old man. The patient initially had a rash and pruritus before presenting with a pedunculated scrotal mass surrounded by widespread erythema. He underwent total gastrectomy for adenocarcinoma 1 year previously and had been receiving TS-1 (Tegafur/Gimeracil/Oteracil pottasium) orally. Histopathologically, the tumor consisted of invasive SCC, with invasive EMPD in the erythematous region. From the clinical presentation and histopathological findings, we assumed that CSCC developed in the background of the EMPD. The CSCC metastasized to several inguinal lymph nodes and to the brain in the following years. While the histogenesis of each of the tumors remains to be elucidated, the fact that the CSCC rather than the EMPD metastasized to a distant site in this patient is to be noted for future treatment considerations.