Serous papillary adenocarcinoma of the tunica vaginalis of the testis with metastasis. Testicular or paratesticular neoplasms that resemble the common epithelial type of ovarian tumor are quite rare. The authors report the case of a 29-year-old man with a metastatic serous papillary adenocarcinoma arising from the tunica vaginalis. To the authors' knowledge, this is the first reported case of a serous carcinoma of the tunica vaginalis behaving in a malignant fashion. The fact that clinically apparent metastatic disease occurred 4 years after initial presentation suggests that development of metastases is a late event. Unfortunately, the tumor has been refractory to therapy with chemotherapeutic agents with activity against ovarian malignancies. 