Unveiling the invisible: the role of multimodality imaging in diagnosing primary cardiac lymphoma.

Primary Cardiac Lymphoma (PCL) is a rare malignancy that frequently masquerades as other cardiac conditions or may be missed due to nonspecific clinical presentations. This diagnostic challenge necessitates a comprehensive imaging approach to ensure accurate differentiation and management. A 54-year-old female presented with palpitations, chest discomfort, slight troponin elevation and lateral ST-segment depressions mimicking acute coronary syndrome. Initial transthoracic echocardiography (TTE) revealed a peri-atrial mass. Cardiac Computed Tomography (CCT) ruled out coronary artery disease. Instead, CCT showed a hypodense process exhibiting the "encasement sign" around the left circumflex artery. Cardiac Magnetic Resonance (CMR) further characterized the mass with T2/T1 hyperintensity and delayed enhancement, narrowing the differential to lymphoma versus IgG4-related disease. 18 F-FDG PET/CT demonstrated intense hypermetabolism and crucially identified a hypermetabolic paratracheal lymph node. Biopsy of the paratracheal node, chosen for its accessibility over cardiac tissue, confirmed diffuse large B-cell lymphoma. The patient was initiated on the Pola-R-CHP protocol (Polatuzumab vedotin, Rituximab, Cyclophosphamide, Doxorubicin, Prednisone). Interim PET/CT after three cycles showed a partial metabolic response. This case underscores the pivotal role of multimodality imaging in "unveiling" PCL. The integration of TTE, CCT, CMR, and PET/CT was essential not only for excluding common etiologies like ischemia but also for identifying safe extracardiac biopsy targets, facilitating timely immunochemotherapy.