多発性骨髄腫に合併した免疫グロブリン性アミロイドーシスによる右房内血栓の1例

Right Atrium Thrombus Due to Cardiac Amyloidosis；Report of a Case

はじめに　アミロイドーシスは心不全や不整脈を高率に伴い，また突然死を高頻度にきたす予後不良の疾患である1～6）．洞調律下においても心腔内血栓を伴うことがあり，致死的塞栓症が高率に生じるとされているが7，8），血栓に対する治療に関しては議論がある．われわれは右房内の腫瘍状を呈した血栓に対する外科的血栓摘除術を契機に，免疫グロブリン性（AL）アミロイドーシスと診断された症例を経験したので報告する．

A 51-year-old man complaining of exertional dyspnea and syncope was admitted to our hospital. Computed tomography （CT） and transesophageal echocardiography demonstrated a mobile tumor-like lesion in the right atrium. Surgical resection was performed under cardioplegic arrest, which revealed an organized thrombus. Pathological examination revealed amyloid deposition in the myocardium, and bone marrow biopsy revealed CD138 （＋） stem cells. Therefore, the patient was diagnosed with amyloid light-chain （AL） amyloidosis associated with multiple myeloma. Although he required percutaneous cardiopulmonary support for postoperative right heart failure for 3 days, he recovered well and was discharged from the hospital on day 44, in a good condition. He was treated with bortezomib for multiple myeloma after surgery. Thus, despite the maintenance of sinus rhythm, intra-cardiac thrombus could be formed with amyloidosis.