Cardiac Tamponade From Lymphocytic Constrictive Pericarditis in Primary AL Amyloidosis Without Myocardial Involvement.

BACKGROUND: Isolated pericardial involvement in systemic light chain (AL) amyloidosis without myocardial infiltration is extraordinarily rare. Constrictive pericarditis with cardiac tamponade as the sole cardiac manifestation has not been previously reported. CASE SUMMARY: A 69-year-old man presented with exertional dyspnea and was diagnosed with a large pericardial effusion with features of constrictive pericarditis. Pericardiocentesis and pericardial biopsy showed lymphocytic effusion without cardiac amyloid involvement. Biopsy of a prevertebral mass later revealed amyloid deposition, confirming systemic AL amyloidosis. He was treated with immunochemotherapy but was unfit for autologous stem cell transplant. DISCUSSION: This case highlights the diagnostic challenges of AL amyloidosis, especially with concomitant pericardial disease without myocardial involvement. Pericardial disease may reflect an inflammatory process rather than direct amyloid infiltration. Diagnosis is challenging given atypical presentations and limited sensitivities of initial monoclonal protein testing. TAKE-HOME MESSAGES: Consider AL amyloidosis in unexplained pericardial disease. Negative monoclonal studies do not exclude systemic amyloidosis. Pursue myocardial biopsy if suspicion persists.