Cardiac Septal Metastasis From Poorly Differentiated Colorectal Adenocarcinoma: A Rare Case Illustrating the Role of Multimodal Imaging and Multidisciplinary Management.

Background: Cardiac metastases from colorectal adenocarcinoma are rare and may present with varied or absent symptoms. Case Summary: A middle-aged woman with recurrent colorectal adenocarcinoma presented with an infiltrating ventricular septal cardiac mass. Multimodal imaging, including PET-CT and cardiac MRI, was crucial for both identifying the lesion as a metastasis and for subsequent serial monitoring. Extensive cardiac involvement necessitated specialized surgical and radiation oncology expertise at a high-volume center, though extra-cardiac lesions led to deferring surgery or radiation as therapeutic options. Ultimately, lesion regression was achieved with intensive chemotherapy and immunotherapy targeting the primary malignancy. Discussion: To our knowledge, no prior cases have documented colorectal adenocarcinoma metastasizing to the interventricular septum with interatrial extension. Management of intracardiac metastases is complex and requires a multidisciplinary approach. Take Home Messages: Accurate diagnosis and characterization of cardiac masses requires a multimodal imaging approach, while effective management depends on a multidisciplinary strategy tailored to treatment goals and patient-specific factors. Surgical resection can be considered at high-volume centers but may be deferred in metastatic disease if it does not improve prognosis or symptoms. Factoring in the expected response to medical therapy is also important.