Abstract 4366207: When Cancer Isn’t Cancer: Unmasking a Rare Cardiac Mass Impersonator

Background: Transthoracic echocardiography (TTE) is a cornerstone for identifying intracardiac pathology due to its accessibility and rapid utility. However, its limited specificity can lead to diagnostic uncertainty in complex or rare cases. CT chest offers broader anatomical detail but lacks the superior tissue characterization of cardiac MRI, which better distinguishes thrombus, tumor, or infection. We present a case of disseminated cardiac aspergillosis that resembled metastatic cancer on TTE and CT, delaying treatment. Case: A 65-year-old woman with end-stage renal disease status post renal transplant and on chronic immunosuppression presented with two days of worsening dyspnea. She was hypotensive and tachycardic but afebrile and without leukocytosis. TTE showed a moderate pericardial effusion with early tamponade physiology and a partially mobile 1.8 × 1.0 cm mass attached to the posteromedial papillary muscle, interpreted as tumor or thrombus (Figure 1). Cardiac MRI was recommended but deferred due to instability. CT chest with contrast revealed several pulmonary nodules, two masses in the right breast, and an enlarged mediastinal lymph node—findings suggestive of widespread malignancy (Figure 2). The patient then exhibited altered mental status, prompting a CT scan of the head, which identified ring-enhancing lesions in the brain (Figure 3). Subsequently, samples of blood and pericardial fluid revealed the presence of disseminated Aspergillus fumigatus . Discussion: TTE and CT chest are useful for evaluating cardiopulmonary pathology but lack the resolution, tissue characterization, and perfusion detail that cardiac MRI provides to differentiate tumors, thrombi, vegetations, and other masses in ambiguous cases. This case highlights the need for a broad differential in immunocompromised hosts, where rare infections may mimic malignancy and where MRI may not be feasible, potentially postponing diagnosis and treatment. Disseminated aspergillosis is an uncommon yet lethal condition that should be considered in high-risk populations. Conclusion: In immunocompromised patients, intracardiac masses or effusions on TTE or CT chest warrant a broad differential diagnosis. Fungal infections like disseminated aspergillosis may closely resemble malignancy, which can delay diagnosis and treatment. Early consideration of empiric antifungal therapy or cardiac MRI—when feasible—may improve outcomes.