Diffuse Myocardial Metastases From Neuroendocrine Malignancy

Neuroendocrine tumors of the thymus (NETT) are rare anterior mediastinal tumors known for their aggressive metastatic potential. This case report describes a middle-aged patient who presented with dyspnea. Multimodality imaging, including computed tomography (CT), transthoracic echocardiography (TTE), cardiac magnetic resonance imaging (MRI), and Gallium-68 DOTATATE positron emission tomography (PET), was used to suggest a diagnosis of NETT, which was confirmed by biopsies of the mediastinal mass and myocardium. Chemotherapy and octreotide were initiated, and follow-up DOTATATE PET demonstrated a partial treatment response. In the absence of appropriate clinical history and ancillary imaging findings, such as an adjacent mediastinal mass, the cardiac imaging features observed in this case (biventricular enlargement with patchy, diffuse myocardial hyperenhancement) may present a diagnostic dilemma because they are nonspecific. This case highlights the importance of distinguishing myocardial metastasis from hypertrophic cardiomyopathy (HCM) and infiltrative cardiomyopathy.