胸骨裏面に限局発生した免疫グロブリンG4（IgG4）関連線維性縦隔炎の1例

Immunoglobulin G4 （IgG4）-related Fibrosing Mediastinitis Localized in the Retrosternal Area：Report of a Case

はじめに　線維性縦隔炎は比較的まれな疾患であり，気管や胸部大血管周囲など，中縦隔から後縦隔にかけて発生することが多い．細菌や結核菌，Histoplasma capsulatumなどの抗原に対する遅延型過敏反応が原因として考えられてきたが1），免疫グロブリンG4（IgG4）関連疾患との関連についても近年報告されている2）．われわれは，前縦隔の胸骨裏面の軟部組織に限局した肥厚性病変を認め，切除生検によりIgG4関連疾患と診断した線維性縦隔炎の1例を経験したので，若干の文献的考察とともに報告する．

An 84-year-old man was referred to our out-patient clinic with an elongated mass localized to the retrosternal area that was incidentally identified by computed tomography. On 18F-fluorodeoxyglucose-positron emission tomography, this lesion showed intense tracer uptake. Thus, a surgical biopsy under thoracoscopy was performed. Histological examination revealed dense fibrous tissue associated with inflammatory cell infiltration. The immunoglobulin （Ig） G4/IgG plasma cell ratio was over 90％. Serum IgG4 levels were normal. According to the Umehara criteria for IgG4-related disease, a final diagnosis of a “possible” IgG4-related fibrosing mediastinitis was made. Oral glucocorticoid treatment with 30 mg/day prednisolone reduced the mass.