Cardiac metastasis from lung squamous cell carcinoma on 18 F-FDG PET/CT

Myocardial metastases from lung cancer are uncommon and often clinically occult. A 72-year-old male who had undergone pneumonectomy for stage IIB squamous cell carcinoma (SCC) presented 9 months later with a newly developed thoracic wall mass. Restaging 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) revealed infiltrative myocardial metastases involving the interventricular septum extending toward the left ventricular apex. Echocardiography demonstrated corresponding regional wall thickening and hypokinesia. Mild perivascular FDG uptake along the left anterior descending (LAD) coronary artery raised suspicion of contiguous myocardial infiltration. Additional metastatic lesions were identified in the thoracic wall and skeletal muscles, including the rhomboid major and vastus intermedius muscles. Follow-up contrast-enhanced CT showed progressive diffuse myocardial thickening, further supporting an infiltrative metastatic process. Despite planned systemic chemotherapy, the patient experienced rapid clinical deterioration and died 41 days after restaging imaging while receiving palliative care. This case highlights the value of 18 F-FDG PET/CT in detecting clinically occult myocardial and skeletal muscle metastases during restaging of thoracic malignancies.