Lokunarangoda Niroshan, Rasnayake Dhammike, Dulanjana Miyuru, Samarasinghe Duminda, Wariyapperuma Ushani
Department of Medicine and Mental Health, Faculty of Medicine, University of Moratuwa, Moratuwa , Sri Lanka.
National Hospital for Respiratory Diseases, Welisara, Sri Lanka.
BMC Pulm Med. 2025 Sep 1;25(1):418. doi: 10.1186/s12890-025-03888-3.
Thymolipoma is a rare benign anterior mediastinal tumour composed of thymic and adipose tissue, accounting for only 2-9% of thymic neoplasms (Mohamud et al., J Surg Case Rep 2020,2020; Shrivastava and Ntiamoah, Radiol Case Rep 15:1538-1540, 2020). Patients are often asymptomatic, and these masses are often detected incidentally. We present a case of a young male with an anterior mediastinal thymolipoma that initially mimicked dextrocardia and cardiomegaly based on findings from clinical examination and chest radiography.
A 22-year-old university student was incidentally noted to have abnormal findings on cardiorespiratory examination. A chest X-ray suggested dextrocardia with cardiomegaly, but further imaging revealed a large anterior mediastinal mass. Contrast-enhanced computed tomography (CT) of the chest showed a well-encapsulated, predominantly fat-density mass (approximately 24 × 15 × 12 cm) in the anterior mediastinum extending into the right hemithorax without invasion of adjacent structures. The lesion caused rightward mediastinal widening but no actual cardiac enlargement, dextroposition or lung collapse. Surgical resection via right mini-thoracotomy was performed. The Gross examination revealed a large, lobulated, encapsulated tumour with a yellow, fatty cut surface and interspersed solid areas. Histopathology confirmed the presence of mature adipose tissue with thymic lobules (cortex, medulla, and Hassall's corpuscles), consistent with thymolipoma, showing no evidence of malignancy. The patient's postoperative recovery was uneventful, and the heart resumed its normal anatomical position.
This case highlights that an anterior mediastinal mass, such as a thymolipoma, can masquerade as dextrocardia and cardiomegaly by distorting the mediastinal silhouette. It is essential to distinguish a mediastinal tumour from true congenital dextrocardia or pulmonary conditions, as each requires markedly different management approaches. Thorough imaging and histological evaluation ensured the correct diagnosis and curative surgical treatment. This report emphasises the importance of considering mediastinal pathology in patients with apparent dextrocardia, as detected during examination or imaging.
胸腺瘤是一种罕见的前纵隔良性肿瘤，由胸腺组织和脂肪组织组成，仅占胸腺肿瘤的2%-9%（Mohamud等人，《外科病例报告》，2020年，2020年；Shrivastava和Ntiamoah，《放射病例报告》15:1538-1540，2020年）。患者通常无症状，这些肿块常为偶然发现。我们报告一例年轻男性前纵隔胸腺瘤病例，该病例最初根据临床检查和胸部X线检查结果被误诊为右位心和心脏肥大。
一名22岁大学生在心肺检查时偶然发现异常。胸部X线检查提示右位心伴心脏肥大，但进一步影像学检查发现前纵隔有一巨大肿块。胸部增强计算机断层扫描（CT）显示前纵隔有一个边界清晰、主要为脂肪密度的肿块（约24×15×12cm），延伸至右半胸，未侵犯相邻结构。该病变导致纵隔向右增宽，但无实际心脏增大、右移或肺萎陷。通过右胸小切口进行了手术切除。大体检查显示一个巨大的、分叶状、有包膜的肿瘤，切面呈黄色、脂肪样，散在实性区域。组织病理学证实存在成熟脂肪组织伴胸腺小叶（皮质、髓质和哈氏小体），符合胸腺瘤，未发现恶性证据。患者术后恢复顺利，心脏恢复正常解剖位置。
本病例强调，前纵隔肿块，如胸腺瘤，可通过扭曲纵隔轮廓而伪装成右位心和心脏肥大。将纵隔肿瘤与真正的先天性右位心或肺部疾病区分开来至关重要，因为每种疾病需要截然不同的治疗方法。全面的影像学和组织学评估确保了正确的诊断和根治性手术治疗。本报告强调了在检查或影像学检查中发现明显右位心的患者中考虑纵隔病理的重要性。
