成田 啓一¹, 金田 智², 陣崎 雅弘¹

Keiichi NARITA¹, Satoshi KANEDA², Masahiro JINZAKI¹

¹慶應義塾大学医学部放射線科学教室（診断）, ²東京都済生会中央病院放射線科

¹Department of Diagnostic Radiology, Keio University School of Medicine, ²Department of Radiology, Saiseikai Central Hospital

キーワード : tuberculous granulomatous epididymo-orchitis, genitourinary tuberculosis, ultrasonography

症例は72歳男性で，1ヵ月前より陰嚢の無痛性腫大を自覚した．陰嚢超音波検査で右精巣上体頭部が腫大し不均一な低エコーを呈していた．低エコー域は右精巣に連続しており，精巣上体との境界が不明瞭であった．また，陰嚢内には結節状の低エコー域を散見した．中等量の陰嚢水腫，軽度の白膜肥厚や陰嚢壁の浮腫を伴っていた．カラードプラ上は精巣上体の辺縁にのみ血流信号を認めた．右精巣腫瘍を疑って，右高位精巣摘除術を実施した．病理組織診断で，膿瘍を伴う肉芽腫形成や炎症細胞浸潤を認めた．中心壊死やラングハンス巨細胞も見られたため，Ziehl-Neelsen染色を実施したが抗酸菌は検出できなかった．結核の既往歴はなく，術後の喀痰・尿培養検査ともに結核菌は検出されなかったが，インターフェロンγ放出試験陽性や胸部CTで陳旧性結核性胸膜炎を示唆する所見があり，最終的に結核性肉芽腫性精巣上体精巣炎と診断した．肉芽腫性精巣上体精巣炎と精巣腫瘍の鑑別は困難とされているが，自験例のように精巣上体の腫大や精巣内部に複数の低エコー結節，血流信号が辺縁のみで内部では乏しいことが診断に有用と考えられた．腫瘍よりも炎症性疾患を示唆する所見として，陰嚢壁肥厚，白膜肥厚，陰嚢水腫も参考になる．

A 72-year-old male with indolent scrotal swelling of one month’s duration was admitted to urology. Scrotal ultrasonography showed abnormalities of the right epididymis and testis. An enlarged epididymal head was heterogeneously hypoechoic, and the border of the right epididymis and testis was ill-demarcated because an epididymal hypoechoic lesion spread into the testis. A sonogram of the right testis revealed multiple small hypoechoic nodules. In addition, there were moderate hydrocele, thick tunica albuginea, and scrotal wall edema. Color Doppler imaging revealed a few signals localized to the periphery of the epididymis. We suspected a right testicular tumor and performed high orchidectomy. Pathologically, there were granulation tissues with abscess, caseation necrosis, and Langhans giant cells. The patient had no history of pulmonary tuberculosis, and Mycobacterium tuberculosis was not detected by Ziehl-Neelsen stain nor isolated from the sputum and urine. We ultimately diagnosed tuberculous granulomatous epididymo-orchitis based on positive interferon-gamma release assays and computed tomography findings of old tuberculous pleurisy. It is often difficult to differentiate this disease from testicular tumor, but the presence of an enlarged epididymis, multiple small hypoechoic nodules in the testis, and Doppler signals localized at the periphery may be useful in making an accurate diagnosis. Findings that suggest inflammatory disease rather than a testicular tumor might be also helpful: scrotal wall thickening, thick tunica albuginea, and hydrocele.