A 24-year-old man presented with recurrent episodes of unexplained syncope over the past 2 months. He denied having chest pain, breathlessness, or fever. Physical examination revealed a mid-diastolic rumble at the apex and an intermittent grade II/VI ejection systolic murmur at the 2nd right intercostal space. His baseline electrocardiogram was normal. 2D transthoracic echocardiography revealed a large non-calcified multilobulated pedunculated and mobile intracardiac mass present on both mitral leaflets. Mitral leaflets were thickened and domed resulting in moderate mitral stenosis. The mobile mass also resulted in left ventricular outflow obstruction causing recurrent syncope (Panels A and B, Supplementary material online, Video S1Supplementary material online, Video S1). Cardiac magnetic resonance imaging revealed a 2.2 cm × 1.9 cm multilobulated mass involving both mitral leaflets (Panels C and D). Late gadolinium enhancement images demonstrated progressive peripheral enhancement with central non-enhancing areas (Panel E). The patient subsequently underwent tumour excision and mitral valve replacement. Intra-operative inspection of the mass revealed friable nodules over the atrial and ventricular surface of both mitral leaflets (Panel F). Histopathological examination of the tumour demonstrated neovascularization and fibrinous deposits with Aschoff nodules comprising collagen degeneration and Anitschkow cells (plump macrophages with caterpillar-like chromatin), characteristic of rheumatic carditis and acute rheumatic fever (ARF) (Panels G and H). Laboratory investigations revealed grossly elevated anti-Streptolysin O titres and erythrocyte sedimentation rate. He was subsequently initiated on oral glucocorticoids and penicillin prophylaxis for ARF and did well on follow-up. Small verrucous rheumatic valvular nodules on echocardiography may be transiently seen in up to 25% of patients with ARF. Rheumatic nodules presenting as a large, mobile, pedunculated intracardiac mass on the mitral leaflets has hitherto not been reported. ARF may present in a myriad of manifestations, and prompt identification is essential to enable the interruption of valvular progression.

中文翻译：

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伪装成心内肿块的急性风湿热二尖瓣结节

一名 24 岁男性在过去 2 个月内反复发作不明原因晕厥。他否认有胸痛、呼吸困难或发烧。体格检查显示心尖部有舒张中期隆隆声，右侧第 2 肋间有间歇性 II/VI 级射血收缩期杂音。他的基线心电图正常。2D 经胸超声心动图显示两个二尖瓣叶上存在一个大的非钙化多叶带蒂和可移动的心内肿块。二尖瓣小叶增厚并呈圆顶状，导致中度二尖瓣狭窄。移动肿块还导致左心室流出道梗阻导致反复晕厥（面板 A和B，在线补充材料，视频 S1 在线补充材料，视频 S1）。心脏磁共振成像显示一个 2.2 cm × 1.9 cm 多叶肿块，累及两个二尖瓣（图 C 和 D）。晚期钆增强图像显示中央非增强区域的渐进性外围增强（图E）。患者随后接受了肿瘤切除和二尖瓣置换术。肿块的术中检查显示两个二尖瓣的心房和心室表面有易碎结节（图F）。肿瘤的组织病理学检查显示新血管形成和纤维蛋白沉积物，包括胶原变性和 Anitschkow 细胞（具有毛虫样染色质的丰满巨噬细胞）的 Aschoff 结节，风湿性心脏炎和急性风湿热 (ARF) 的特征（图G和H）。实验室调查显示抗链球菌溶血素 O 滴度和红细胞沉降率显着升高。随后他开始口服糖皮质激素和青霉素预防 ARF，并在随访中表现良好。高达 25% 的 ARF 患者在超声心动图上可能会暂时看到小的疣状风湿性瓣膜结节。风湿性结节在二尖瓣上表现为一个大的、可移动的、有蒂的心内肿块，迄今尚未见报道。ARF 可能有多种表现，及时识别对于阻断瓣膜进展至关重要。