“ステロイド単独投与が奏効した巨細胞性心筋炎”と当初みなされた心サルコイドーシスの1例

A Case of Cardiac Sarcoidosis Initially Misdiagnosed as Giant Cell Myocarditis and Treatable by Single Steroid Therapy

要旨　患者は55歳，女性．2005年4月，動悸と呼吸困難を主訴に受診し，心室頻拍と肺うっ血を指摘された．左室壁運動は軽度低下を認めるのみで，標準的な薬物治療で軽快した．しかし，経時的にPQ時間が漸増し，2006年9月には完全房室ブロックが出現した．さらに，瘤状変化を伴う高度な左室壁運動低下を認めた．心筋生検にて，非乾酪性肉芽腫が不明瞭で多数の巨細胞を認めたことから巨細胞性心筋炎と診断し，ステロイド投与のみで房室伝導が改善した．慢性経過，進行性の心伝導障害，単独ステロイド奏効の臨床像から確定診断に疑問を抱き，心筋生検所見の組織学的検討につき免疫染色法を追加し再評価を行った．高度な線維化とともに境界不明瞭な肉芽腫様病変を識別でき，診断として心サルコイドーシスのほうがむしろ妥当と判断を修正した．巨細胞性心筋炎と心サルコイドーシスとの鑑別困難例では，組織および臨床所見の両者を併せた判断が求められる．

　A 55-year-old woman was admitted due to palpitation and breathlessness arising from ventricular tachycardia with mild hypokinesia of the left ventricle. After conventional pharmacological therapy, she was relieved of her symptoms by the time of her discharge. Her electrocardiogram showed gradual prolongation of the PQ interval, finally leading to asymptomatic complete atrioventricular(AV) block after 1.5 years. The left ventricle showed severe hypokinesia with multiple aneurysmal deformities and extensive myocyte injury with inflammatory infiltrates in the endomyocardial biopsy specimen consisting of lymphocytes and multinucleated giant cells. After histological diagnosis of giant-cell myocarditis, a single steroid administration rapidly improved AV conduction. Considering the peculiar clinical figures such as the chronic progressive clinical course, cardiac conduction abnormalities, and marked effectiveness of single steroid therapy, close histological re-evaluation of the biopsy sample including immunohistochemical analyses was undertaken, and the conclusion was a diagnosis of cardiac sarcoidosis due to recognized granulomatous lesions with marked interstitial fibrosis. In clinical practice, we need to realize the usefulness of combined diagnostics methodology utilizing both histological and clinical evaluation in order to differentiate giant cell myocarditis from cardiac sarcoidosis.