Solitary fibrous tumor in the retroperitoneum: a case with infiltrative growth

Abstract

56歳女.悪性後腹膜孤立性線維性腫瘍であり, 主訴は腹部腫瘤触知で, 腹部CT及びMRI検査にて左腎下方に接して, Gerota筋膜に沿うように発育する境界不明瞭な腫瘤を認めた.手術所見では後腹膜腔にゼラチン状の腫瘍を認め, 下行結腸周囲の脂肪組織やGerota筋膜周囲の脂肪組織に浸潤していた.Gerota筋膜内への浸潤は認めなかったので左腎は温存した.病理組織像では間質の膠原線維は著明に増殖し, hemangiopericytoma様のくちばし状を呈する血管も豊富に認められた.腫瘍組織内に腫瘍細胞密度の増加しているところや核異型度が強く分裂像を認める組織が混在しており, また周囲脂肪組織内に浸潤している所見を認めた.以上より, 悪性後腹膜孤立性線維性腫瘍と診断した.治療は外科的切除のみを行い, 2年4ヵ月を経過しても再発無く生存中である

Solitary fibrous retroperitoneal tumor is rare. We present a case with infiltrative growth in a 56-year-old female patient whose initial symptom was palpable tumor in the lower abdomen. Computed tomography and magnetic resonance imaging indicated a mass in the retroperitoneum under the left kidney with a poorly demarcated infiltrative growth. Surgical findings revealed a gelatinous tumor in the retroperitoneum, which had invaded up to the fatty tissue surrounding the Gerota's fascia and to the fatty tissue surrounding the descending colon. However, as there was no invasion into the Gerota's fascia, it was possible to preserve the left kidney. Pathohistological examination revealed increased cellularity in the tumor tissues as well as tissues with atypical nuclei of the tumor cells with some cell division. Due to these findings, it was diagnosed as malignant solitary fibrous tumor. Only surgical treatment was performed and the patient is alive without recurrence 2 years and 4 months after surgery.