When Cancer Looks Like Cardiomyopathy: Cardiac Lymphoma masquerading as HCM

Description of Clinical Presentation: A 14 year old girl with no previous history started in april 2023 with chronic abdominal pain, diarrhea and weight loss. In January 2024 at the ER she was diagnosed with cholestatic syndrome and malignancy was supected due to chronic weight loss, cervical adenopathy and tender hepatomegaly.

Diagnostic Techniques and Their Most Important Findings: On inital imaging cardiomegaly and septal hypertrophy was picked up which prompted cardiology consultation. Oncology workup was initiated which included abdominal US, chest and abdominal CT & MRI, PET/CT, lymph node biopsy, bone marrow aspirate and lumbar puncture. Stage E-IV diffuse large B cell non Hodgkin lymphoma was diagnosed and she received 6 cycles of R-CHOP with Dexrazoxane.
A transthoracic echocardiogram showed left ventricle septal hypertrophy and inferior pericardial effusion. Cardiac MR was requested which showed biventricular hypertrophy (assymetrical hypertrophy of the septum and free wall of the RV and increased thickness at the interatrial septum) with normal EF of both ventricles. At the level of maximal septal hypertrophy there was evidence of perfusion defects at rest, increased signal intensity on T2w images and diffuse patchy late gadolinum enhancement. Four months later, follow-up CMR revealed decrease in ventricular wall thickness to normal values without perfusion defects, negative T2w images,and persistent patchy LGE. Last CMR on august 2025 showed normal EF of both ventricles, normal wall thickness including both atrial and ventricular septa, and persistent LGE at ventricular septum with a small inferior pericardial effusion. Since June 2024 her PET/CT scans have come back negative for neoplasia and she is currently asymptomatic.

Learning Points from this Case:

• CMR is mandatory in any thick ventricle


• Always bear in mind phenocopies in the differentials of any hypertrophic heart disease


• When suspecting cardiac infiltrative disease look out for specific patterns such as: IAS hypertrophy, persistent pericardial effusion, patchy/transmural LGE, perfusion defects.


• CMR can improve our understanding of mechanisms of cellular damage in secondary cardiac lymphoma.


• Unanswered questions such as clinical impact of persistent LGE need further study.

Diagnostic Clues for Detection of HCM Mimics. IEM: inborn errors of metabolism MC: mitochondrial cythopathies DD: Danon’s FD: Fabry CA: Amyloidosis HHD: Hypertensive heart GSD: Glycogen storage RAS: rasopathies

	HCM (primary/sarcomeric)	Genocopy/ Phenocopy
Age at presentation	Young adult-middle age (3rd decade)	•Neonate/Infant: IEM, MC •Adolescence-young adult: DD, FD, PRKAG2 •Middle age: CA, FD, HHD •Elderly: CA
Extracardiac	None	•Multisystem involvement:       IEM, FD, DD, RAS, Amyloidosis,
Blood tests		• Renal failure: FD, CA •  CK: DD, MC, PD
ECG	LVH pattern T wave inversion (apical HCM) Q waves LAFB	•Pre-excitation: DD, FD, GSD, PRKAG2 •AV block: PRKAG2, MC, FD, AD, GSD •QRS complexes: •Small: CA •Large: GSD, Danon
CMR	Asymmetric, septal, apical LVOT obstruction (SAM)	•LGE Inferolateral: FD •LGE Subendocardial global: AD •LGE Diffuse sparing med-septum: DD •Biventricular hypertrophy: GSD, DD •Dilated phase: DD, GSD

Cardiac MR before and after chemotherapy.
Follow-up CMR with shows normal wall thickness but persistent septal LGE.
PET/CT scans