Acute lymphoblastic leukemia presenting as myocardial infiltration mimicking hypertrophic cardiomyopathy: a case...

Acute lymphoblastic leukemia (ALL) with myocardial infiltration is a rare extramedullary manifestation, typically encountered in advanced or relapsed disease. Presentation as an isolated, reversible hypertrophic cardiomyopathy (HCM)-like phenotype without typical hematological symptoms is exceptional and poses a major diagnostic challenge.

A 25-year-old man presented with fever, weight loss (20 kg over 3 months), progressive dyspnea, and bilateral lower extremity edema. Echocardiography and CMR imaging revealed severe asymmetrical left ventricular hypertrophy (maximum septal thickness 27 mm) with reduced left ventricular ejection fraction (as low as 27%), initially suggesting non-obstructive HCM. However, the presence of persistent fever, a marked inflammatory response (C-reactive protein 129 mg/L; reference: <10 mg/L), and elevated D-dimer and the lack of a family history or cardiovascular risk factors raised suspicion. Whole-body [¹⁸F]FDG PET-CT demonstrated intense myocardial uptake (SUVmax 14.8) along with widespread lymphadenopathy and splenic involvement. Peripheral blood smear showed 23% lymphoblasts, and bone marrow examination confirmed T-cell acute lymphoblastic leukemia (T-ALL) with myeloid co-expression. Endomyocardial biopsy revealed diffuse infiltration by T-lymphoblastic cells (CD3⁺, CD5⁺, TdT⁺). The patient received three cycles of chemotherapy (VDPL, venetoclax+chidamide+azacitidine, mitoxantrone+cytarabine). At follow-up after three cycles, bone marrow minimal residual disease was negative, and repeat echocardiography showed normalization of cardiac structure and function.

This case illustrates that T-ALL can first manifest as a rapidly progressive, HCM-mimicking cardiomyopathy that is fully reversible with effective chemotherapy. Clinicians should suspect hematologic malignancy in a young patient with unexplained cardiac hypertrophy associated with constitutional symptoms, elevated inflammatory markers, and poor response to standard therapy for heart failure. Early bone marrow examination and, if necessary, endomyocardial biopsy can confirm the diagnosis.