巨大前立腺葉状腫瘍の一例  [in Japanese] GIANT PHYLLODES TUMOR OF THE PROSTATE  [in Japanese]

骨盤腔を超え後腹膜腔を占拠する巨大前立腺葉状腫瘍を経験したので報告する.症例 : 55歳男性.主訴 : 排尿困難腹部膨満.既往歴 : 胃潰瘍.現病歴 : 飲酒後の尿閉を主訴に紹介受診.腹部全体の腫瘤を蝕知した.CTで会陰〜上腹部まで占拠する29×12×43cmの腫瘤を認め骨盤内右側より発生した巨大後腹膜腫瘍の疑いで外科にて腫瘍摘出術施行.腫瘍は後腹膜に存在し小骨盤腔をほぼ占拠する8.6kgの巨大腫瘍であった.病理組織学検査ではprostatic stromal tumor of uncertain malignant (phyl-lodes tumor/epithelial stromal tumor)の診断であったため術後当科紹介,初診時PSA3.9ng/mlが術後0.9ng/mlに下降していたが,MRIでは骨盤内に径10cmの前立腺と境界不明瞭な残存腫瘍を認め,残存腫瘍,前立腺全摘術を施行した.前立腺葉状腫瘍は組織学的に上皮成分と間質成分の混合腫瘍であり間質の組織型で悪性度が判定される.治療は外科的切除術がもつとも多く行われ,経尿道的腫瘍切除(TUR-P)にとどまるものは高率に再発が認められ,転移による癌死の報告がある.稀な疾患のため定まった治療法はないのが現状であるが,残存腫瘍からの再発は高率であり,慎重な経過観察が必要と考えられた.

A 55 year-old man complained dysuria and visited to our hospital. Physical examination showed firm large mass occupying whole abdomen. Computed tomography (CT) demonstrated a huge retroperitoneal tumor which compressed intestine, liver, kidney, and urinary bladder. We performed extirpation of the tumor (8.6 kg, largest diameter 60 cm) which was composed of myxoid stromal region associated with cystic pattern. Histological examination revealed that the epithelium of the cystic region was positive for prostate specific antigen (PSA) immunostaining. The tumor was diagnosed phyllodes tumor of the prostate (prostatic stromal proliferation of uncertain malignancy, PSTUMP). Serum PSA was declined 3.9 ng/ml to 0.9 ng/ml ; however, magnetic resonance imaging (MRI) demonstrated a residual (recurrent?) tumor in the pelvis one month after the operation. We carried out total prostatectomy and residual tumor resection. Phyllodes tumor of the prostate is histologically characterized with biphasic pattern of hyperplastic epithelial cysts and variably cellular spindle stroma. The tumor is considered to have malignant potential and several histological factors including cellularity, atypia, etc. are utilized to assess it. However diagnostic criteria and subsequent treatment modalities are not established thus far. Previous reports showed efficacy of total surgical removal rather than partial resection and that we performed radical extirpation of the entire tumor. Close follow up is needed against this frequently recurrent disease.