Para-atrial non-acute mediastinal hematoma after left atrial maze procedure mimicking tumor in a patient with treated melanoma

Introduction: The Cox Maze III procedure is considered the gold standard open surgical procedure for management of atrial fibrillation. This article outlines a unique case of a para-atrial mediastinal hematoma following a bilateral thoracoscopic left atrial Maze procedure mimicking malignancy. Report: A 60-year-old male, with past history of melanoma, underwent bilateral thoracoscopic left atrial mini maze procedure with radiofrequency energy and exclusion of the left atrial appendage. Seven months later, a chest computed tomography (CT) scan was performed to evaluate for pulmonary embolism. The CT scan unexpectedly showed an ill-defined, heterogeneous para-atrial mass immediately superior to the left atrium concerning for tumor and mediastinal adenopathy. The mass was moderately hypermetabolic on subsequent 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) scan. A follow-up PET/CT three months later demonstrated near-complete resolution of the para-atrial mass with minimal residual hematoma. Conclusion: Non-acute mediastinal hematoma following a maze procedure can potentially be confused with a tumor mass and/or lymphadenopathy on CT and FDG PET/CT. With knowledge of the potential for false-positive FDG uptake in a hematoma, the lesion was monitored, and unnecessary biopsy was avoided.