Histopathological Variants of Atrial Myxoma with Emphasis on Glandular Differentiation: A Cross-sectional Study

Introduction: Atrial myxomas are rare benign cardiac tumours with a variable clinical presentation, including obstructive symptoms, systemic embolisation, and constitutional manifestations. Echocardiography is the primary diagnostic modality, but histopathology remains the gold standard for confirmation. While most myxomas display a classic myxoid matrix with stellate cells, glandular differentiation is an uncommon variant that can mimic adenocarcinoma, necessitating immunohistochemical analysis. This study examines the histopathological diversity of atrial myxomas and its clinical implications. Aim: The aim of the present study was to analyse the histopathological spectrum of atrial myxomas, identify rare variants, and differentiate them from potential mimickers to aid accurate diagnosis and clinical management. Materials and Methods: The present retrospective cross-sectional study of 12 atrial myxoma cases was conducted at Jagjivan Ram Hospital, Mumbai, from January 2018 to December 2024. Gross and microscopic features were examined, supplemented by special stain (Alcian blue) and Immunohistochemistry (IHC) using markers such as (Cytokeratin 7 (CK7), Cytokeratin 20 (CK20), Caudal Type Homeobox 2 (CDX2), Carcinoembryonic Antigen (CEA), Calretinin, Cluster of Differentiation 31 (CD31), and Ki-67 protein (Ki-67) proliferation index. The findings were analysed for histopathological variations and their diagnostic significance. Results: Eleven out of 12 cases involved the left atrium, and one case had bilateral atrial myxomas. Grossly, tumours were gelatinous and grey-white, with villous or lobulated surfaces. Microscopically, all cases showed myxoid stroma with stellate (lepidic) cells, haemosiderin-laden macrophages, and fibrosis. One case displayed glandular structures lined by columnar cells with mucin droplets, diagnosed as glandular myxoma. IHC confirmed CK7 and calretinin positivity in glandular areas, differentiating it from adenocarcinoma. Conclusion: Atrial myxoma presents with diverse clinical manifestations and potential complications. Accurate histopathological evaluation is essential for diagnosis, differentiation from adenocarcinoma, and detection of lymphovascular emboli. Recognising histological variants and mimickers is crucial for guiding management and preventing misdiagnosis.