後腹膜腫瘍に対し腹腔鏡下摘出術を施行したCastleman病の1例

A case of Castleman's disease in the retroperitoneum resected by laparoscopic surgery

◆要旨：患者は65歳，男性．半年前より下腹部痛が持続し，腹部CTで後腹膜に脾動脈に接する径20mm大の腫瘤陰影を認めた．以前よりも増大傾向を認め，手術による診断・治療目的に外科を紹介受診した．術前の超音波内視鏡下穿刺吸引法（endoscopic ultrasound-guided fine needle aspiration : EUS-FNA）では悪性所見を認めず，造影MRIではT1強調像で低信号，T2強調像で膵実質よりわずかに高信号を示し，脾臓と同等程度の拡散制限を認めた．後腹膜内のCastleman病や神経鞘腫が鑑別診断に挙がった．腹腔鏡下後腹膜腫瘍摘出術を施行し，経過良好で術後3日目に退院した．病理組織学的検査では腫瘍はリンパ濾胞の過形成と濾胞間領域に著明な形質細胞浸潤と血管増生を認め，形質細胞型Castleman病と診断された．今回われわれは稀な形質細胞型Castleman病と診断した1例を経験したので報告する．

　A 65-year-old man had been suffering from lower abdominal pain for 6 months. An abdominal CT was conducted, which showed a 20 mm nodule in the retroperitoneum area, adjacent to the splenic artery. The nodule had grown larger compared to the findings taken 2 and a half years ago. Therefore he was referred to the surgical department for further diagnosis and for surgical treatment. Preoperative endoscopic ultrasound-guided fine needle aspiration（EUS-FNA） revealed no malignant findings. Contrast-enhanced MRI showed low signal intensity on T1 weighting and slightly higher signal intensity than the pancreatic parenchyma on T2 weighting, with diffusion restriction equivalent to that of the spleen. We suspected Castleman's disease or schwannoma. Laparoscopic resection of the retroperitoneal tumor was performed. The patient recovered well and was discharged third day postoperatively. Histopathological examination revealed lymphoid follicular hyperplasia, marked plasma cell infiltration and vascular proliferation in the interfollicular regions. The tumor was diagnosed as plasma cell type Castleman's disease. We here experienced this rare case of disease, and therefore would like to submit a literature review.