スキルス胃癌と鑑別を要する非腫瘍性疾患―後腹膜線維症

Differential Diagnosis of Retroperitoneal Fibrosis

要旨　後腹膜線維症は，後腹膜の軟部組織が炎症性細胞浸潤や線維化を来した結果，尿管の狭窄から水腎症を来す病態の総称である．疾患の2/3以上を占める原因不明の原発性後腹膜線維症と，続発性後腹膜線維症として，薬剤に起因するものや悪性疾患による浸潤が原因となるものがある．胃癌の中でも後腹膜への浸潤，転移傾向が強いものでは続発性後腹膜線維症を来しうる．したがって，適切な治療を行ううえでも画像診断を中心とした鑑別診断が重要である．

　RPF（retroperitoneal fibrosis）is a rare clinical condition characterised by the presence of a retroperitoneal mass with inflammatory cells and marked fibrosis, which often entraps the ureters and it finally results in hydronephrosis. The idiopathic form of the disease represents more than two thirds of the cases, with the rest being secondary due to other causes such as use of certain drugs and neoplasms infiltrating into the retroperitoneum. Patients with gastric cancer characterised by invasion into the retroperitoneal tissue may be diagnosed as secondary RPF. Imaging modalities, such as CT（computed tomography）and MRI（magnetic resonance imaging）, have provided non-invasive and reliable methods for differential diagnosis of RPF and, consequently, appropriate treatment choice for an individual patient.