石黒 はるか¹, 丸上（高橋） 亜希², 丸上 永晃¹, 三宅 牧人³, 藤本 清秀³, 藤井 智美⁴, 田中 利洋¹, 平井 都始子²

Haruka ISHIGURO¹, Aki TAKAHASHI-MARUGAMI², Nagaaki MARUGAMI¹, Makito MIYAKE³, Kiyohide FUJIMOTO³, Tomomi FUJII⁴, Toshihiro TANAKA¹, Toshiko HIRAI²

¹奈良県立医科大学放射線診断・IVR学講座, ²奈良県立医科大学総合画像診断センター, ³奈良県立医科大学泌尿器科, ⁴奈良県立医科大学病理診断科

¹Department of Diagnostic and Interventional Radiology,Nara Medical University, ²General Diagnostic Imaging Center,Nara Medical University, ³Department of Urology,Nara Medical University, ⁴Department of Diagnostic Pathology,Nara Medical University

キーワード : papillary cystadenoma of the epididymis, ultrasonography, color Doppler imaging, computed tomography

精巣上体乳頭状嚢胞腺腫（papillary cystadenoma of the epididymis：PCE）は精巣上体に発生する稀な良性腫瘍である．常染色体顕性遺伝であるフォンヒッペルリンドウ病（von Hippel-Lindau disease：VHLD）に関連して発生するほか，孤発性にも発生する．悪性化は稀で局所切除が可能，あるいは慎重な経過観察も選択枝となり得る腫瘍性病変であるが，画像のまとまった報告はなくVHLDの既往がない場合には術前診断は難しく高位精巣摘除術が選択される場合も多い．今回我々は孤発性と考えられたPCEの1例を経験したので超音波画像を中心に報告する．症例は70代男性．右鼠径ヘルニアを疑われ撮像された造影CTで左陰嚢内に多血性充実性腫瘤を偶然発見された．超音波検査では腫瘤は左精巣の頭側に隣接して存在し，Bモードで境界明瞭，内部は精巣と等エコーを示し，石灰化と思われる音響陰影を伴う高エコー域を有していた．カラードプラでは腫瘤内の大部分に豊富なカラー表示がみられた．PCEは鑑別の一つに考えられたが傍精巣領域原発の肉腫を否定できないと考え高位精巣摘出術が施行された．病理組織学的に淡明な細胞質とクロマチンが増加した類円形，あるいはやや歪な形の核を有する細胞が乳頭状に増殖する腫瘍で明細胞型の腎細胞癌の転移とPCEの可能性が検討されたが，腎細胞癌の既往がなかったことからPCEとの最終診断に至った．

Papillary cystadenoma of the epididymis (PCE) is a rare benign tumor of the epididymis. It occurs in association with von Hippel-Lindau disease (VHLD), an autosomal manifestation of the disease, and also occurs solitarily. However, there have been few imaging reports, and in the absence of a history of VHLD, a preoperative diagnosis is difficult. As such, orchiectomy is often performed. In this report, we describe a case of PCE that was thought to be solitary, focusing on ultrasound images. The patient was a man in his 70s. A mass with hypervascularity was incidentally detected in the left scrotum on contrast-enhanced computed tomography (CT), suggesting a right inguinal hernia. On ultrasonography, the mass was located adjacent to the cephalic side of the left testis, with clear boundaries in B-mode, and the interior was isoechoic to the testis, with a high echo area with acoustic shadows that appeared to be calcification. Color Doppler showed abundant color in most of the mass, and although PCE was considered as a possible diagnosis, a primary sarcoma in the paratesticular area could not be ruled out, and high orchiectomy was performed. Histopathologically, the tumor was a papillary growth of cells with pale cytoplasm and chromatin-enhanced, similarly round or slightly distorted nuclei. The possibility of metastasis from clear cell renal cell carcinoma and PCE was considered. Ultimately, PCE was clinically diagnosed due to absence of a history of renal cell carcinoma.