A Rare Case of Primary Intracardiac Thymoma on 18 F-FDG PET/CT.

A 63-year-old woman presented with progressive facial edema. 18 F-FDG PET/CT showed a large soft tissue mass with heterogeneous hypermetabolism in the right atrium and superior vena cava, without distant metastases. The patient underwent surgical resection, and postoperative pathology confirmed a primary type B1 thymoma originating from the right atrium. To our knowledge, this case report details the 18 F-FDG PET/CT imaging features of primary intracardiac thymoma, which has rarely been described in the literature. It demonstrates the unique advantages of PET/CT in evaluating tumor malignant phenotype and systemic staging, and enriches the differential diagnosis spectrum of intracardiac hypermetabolic lesions.