Relapsing-Remitting Perimyocarditis and Emerging Acute Myeloid Leukemia.

BACKGROUND: Perimyocarditis as an initial manifestation of acute myeloid leukemia (AML) is rare, with fewer than 5 contemporary cases reported. CASE SUMMARY: A 66-year-old man experienced 7 hospitalizations over 3 months for fever, elevated troponin, and inflammatory markers after Coxsackievirus B exposure. Initial cardiac magnetic resonance (CMR), infectious, and hematologic work-ups were unremarkable. Repeat CMR revealed biventricular dysfunction, new lateral wall late gadolinium enhancement, myocardial edema, and a circumferential pericardial effusion. Endomyocardial biopsy confirmed severe lymphocytic myocarditis. The patient failed 2 corticosteroid tapers but improved with colchicine, intravenous immunoglobulin, and anakinra. After cardiac recovery, peripheral blood and bone marrow evaluation revealed AML. DISCUSSION: This case highlights a potential rare dual-etiology mechanism for perimyocarditis involving viral injury and AML-driven inflammatory activation. TAKE-HOME MESSAGE: This case underscores the diagnostic value of serial CMR with biopsy, the role of interleukin-1 blockade and intravenous immunoglobulin in steroid refractory disease, and vigilance for emerging hematologic malignancy.