大腿に発生した皮下アミロイド腫瘤の1例

Subcutaneous Amiloid Tumor of the Thigh. Case Report

　アミロイド沈着による腫瘤形成は，ほとんどの場合，何かしらの基礎疾患を有する．今回，われわれは何ら基礎疾患を有さず右大腿にアミロイド腫瘤を生じた1症例を経験したので報告する．66歳，男性．右大腿外側から背側にかけて，8×18cmの表面平滑で可動性の乏しい腫瘤を触知した．病理組織検査では滑液包炎の所見と滑膜上皮に限局したアミロイドの沈着を認めた．組織全体がアミロイド沈着で占められるamyloidomaと異なり，大腿後面の皮下滑液包炎にアミロイドが沈着し腫瘤状に増大したものと考えられた．

　Amyloid tumors in soft tissue are rare. The deposition of amyloid usually occurs systemically but is occasionally restricted to a single organ. Although amyloid tumors generally appear as nodular masses of amyloid, the mass in the present case had a cystic character. Histological examination revealed synovial bursitis and amyloid deposition mainly in the synovial epithelium, with comparatively little deposition in the interstitial tissue. The origin of the tumor was thought to be amyloid deposition caused by synovial bursitis secondary to a chronic local soft tissue inflammation.