Prostatic stromal sarcomaの1例

Abstract

33歳, 男。会陰部痛を認め, 近医のMRIでは前立腺は6.5×8cm大に腫大し, 内部は不均一に造影効果を認めた。胸部CTでは結節陰影を数個認め, 転移性肺腫瘍と考えられた。精査加療目的で当科に入院した。前立腺は超鶏卵大, 左右不対称, 圧痛著明であった。血清前立腺特異抗原は軽度上昇していた。骨盤部造影CTでは血流に富む巨大な腫瘤が骨盤内を占め, 内腔に壊死巣と思われる低吸収域を認めた。経直腸的前立腺針生検にて間葉系腫瘍が疑われたが, 確定診断に至らなかった。排尿障害改善目的でpalliative transurethral resectionを施行し, 病理組織学的にprostatic stromal sarcoma, 臨床病期T2bN0M1と診断した。etoposide, ifosfamide, cisplatinによる全身化学療法VIPを施行し, 肺転移巣の50%縮小を認めたが腫瘍は急速に増大した。腫瘍内容が腹腔内に膀胱頂部から破裂流出したため, 手術療法, 姑息的腫瘍血管の塞栓術は断念した。腎機能悪化のため左腎瘻造設を行った。臀部痛, 腰痛は増強し, その後悪液質のため死亡した。

Prostatic stromal sarcoma (PSS) is an unusual lesion that is reported only occasionally. Here we describe a case of prostatic stromal sarcoma in a 33-year-old man who had complained of perineal pain. The serum prostate-specific antigen (PSA) level was above the normal limit at 5.8 ng/ml, and abdominal computed tomography (CT) revealed a giant mass in the retrovesical region. Chest CT demonstrated lung metastases. Specimens obtained by transrectal needle biopsy of the prostate suggested a mesenchymal tumor, but a precise diagnosis required a larger specimen. Palliative transurethral resection (TUR-P) was performed because of obstruction of the urogenital tract, and the final diagnosis was made from this specimen. The tumor contained yellowish gelatinous materials, and the stromal element appeared histologically malignant, with increased cellularity, mitotic figures and pleomorphism. The histological diagnosis was PSS, and the patient received VIP (etoposide, ifosfamide, cisplatin) chemotherapy regimen. However, the pelvic mass continued to increase in size, and the patient's condition rapidly deteriorated and he died. Sarcoma of the prostate gland showing aggressive behavior is quite rare. The detailed histological and immunohistochemical findings in this case are reported, together with a review of the literature.