ABSTRACT Introduction Primary malignant neoplasms of the epididymis are rare. In this case report, we describe clear cell carcinoma associated with papillary cystadenoma of the epididymis (PCE). Case Presentation A 77‐year‐old man presented with a painless, enlarged left scrotum. Magnetic resonance imaging (MRI) revealed two different abnormal signals in the left epididymis. A left high inguinal orchiectomy and histopathological examination revealed a benign component consistent with PCE and a malignant component showing solid growth with cell nuclear enlargement, atypical mitotic figures, and invasion into surrounding tissues. The final diagnosis was malignant transformation to clear cell carcinoma of PCE. Conclusion Although this epididymis tumor may follow an indolent course, the presence of areas with higher proliferative potential suggests surgical excision be recommended as definitive treatment.
Suzuki et al. (Sun,) studied this question.