Constrictive Pericarditis Due to Metastatic Squamous Cell Carcinoma: A Rare and Ominous Condition

Constrictive pericarditis is an uncommon but serious condition typically caused by idiopathic inflammation, prior cardiac surgery, or radiation. Malignancy is a rare etiology.

A 62-year-old man with a history of tongue squamous cell carcinoma on long-term pembrolizumab presented with dyspnea, orthopnea, leg swelling, and ascites. Multimodal imaging revealed nodular pericardial thickening and constrictive physiology. Given lack of improvement on anti-inflammatory therapy and need to differentiate between metastatic disease versus immunotherapy-related inflammation, surgical pericardiectomy with biopsy was pursued. Histopathology confirmed poorly differentiated metastatic carcinoma invading the myocardium. Owing to poor prognosis, care was transitioned to hospice.

Malignant pericardial involvement with constriction is a rare but important diagnostic consideration, particularly when atypical features or poor response to therapy are present. Immune checkpoint inhibitor-associated pericarditis can mimic malignant involvement, complicating noninvasive diagnosis.

When advanced imaging cannot definitively distinguish between immune-mediated and malignant pericarditis, tissue diagnosis is necessary.