Primary adenocarcinoma of the rete testis with elevated serum CA19-9 antigen levels.

Primary adenocarcinoma of the rete testis is an extremely rare tumor with a poor prognosis. Herein, we report a case of primary adenocarcinoma of the rete testis accompanied by elevated serum carbohydrate antigen 19-9 (CA19-9) antigen levels in a 44-year-old man who presented with left scrotal swelling. Para-aortic lymph node swelling was observed on the computed tomography scan. Germ cell tumor markers were within the normal range, but serum CA19-9 antigen levels were high. Radical orchiectomy was performed, and histological examination revealed primary adenocarcinoma of the rete testis with no evidence of other primary carcinomas. The patient underwent three lines of chemotherapy, although no reports suggest the use of gemcitabine and oxaliplatin (GEMOX) in a patient with adenocarcinoma of the rete testis. Unfortunately, he developed metastasis at multiple sites and passed away due to adenocarcinoma 13 months after undergoing orchiectomy. Some reports suggest that CA19-9 antigen levels are elevated in patients with adenocarcinoma of the rete testis, although it has not been clarified whether elevated CA19-9 antigen levels reflect the progression of adenocarcinoma of the rete testis. In this case, as CA19-9 antigen levels increased with progression, CA19-9 might be a marker for primary adenocarcinoma of the rete testis. GEMOX chemotherapy as a line of treatment in primary adenocarcinoma of the rete testis has not been reported. Therefore, further studies must evaluate the efficacy of the aforementioned chemotherapy regimen. © The Japan Society of Clinical Oncology 2020.