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[A case of papillary cystadenoma of the epididymis mimicking a testicular tumor].

A 68-year-old male presented with painless left scrotal enlargement of one year duration. Ultrasound, computed tomography (CT) and magnetic resonance imaging showed a multilocular cystic mass, 10×7.5× 8.5 cm in size, in the left scrotum. The intracystic fluid was partially hemorrhagic. A solid part of the tumor, seen at the base of the scrotum, was partially calcified and was enhanced by contrast medium. The left testis could not be identified by imaging studies. Although CT imaging showed a simple cyst in the right kidney, no other lesions in the kidneys, adrenal glands, pancreas or the central nervous system were detected. Serum tumor marker values for testicular cancer were within the normal range. Under the pre-operative diagnosis of a left testicular tumor, left high orchiectomy was performed. Grossly the specimen consisted of a multilocular cystic tumor, 12.5×8.5×8.5 cm in size, with a 2.7 cm tan-colored solid component within the wall of the cyst. The left testis was atrophic, 1.3 cm in size, and demonstated no continuity with the solid part of the tumor. Histologically, the solid component of the tumor showed tubular and papillary growth of cuboidal and columnar tumor cells with clear cytoplasm. Histopathological diagnosis of papillary cystadenoma of the epididymis (PCE) was made. Von Hippel-Lidau disease was ruled out by subsequent genetic analysis. After follow up for 18 months, there was no sign of recurrence. To our knowledge, this is the 33rd and the largest case of PCE reported in Japan.