What question did this study set out to answer?

To demonstrate the relevance of electron microscopy in distinguishing Fabry disease from hypertrophic cardiomyopathy.

January 10, 2026Cardiovascular Pathology0 citations

Usefulness of electron microscopy in the diagnosis of heterozygous Fabry disease with left ventricular outflow tract obstruction masquerading as hypertrophic cardiomyopathy

HKHiromitsu Kanamori TYTamami YoshidaGifu University HMHideki MatsumotoTokyo Dental College

Key Result

Electron microscopy identified lamellar bodies in cardiomyocytes, confirming heterozygous Fabry disease in a patient initially diagnosed with hypertrophic cardiomyopathy.

Key Points

To demonstrate the relevance of electron microscopy in distinguishing Fabry disease from hypertrophic cardiomyopathy.
Case study of a 42-year-old female with symptoms mirroring hypertrophic cardiomyopathy.
Utilized electrocardiography and echocardiography for initial assessment.
Performed endomyocardial biopsy, followed by electron microscopy for detailed analysis.
Conducted genetic testing to confirm diagnosis.
Echocardiography revealed asymmetric left ventricular hypertrophy and significant LVOT obstruction.
Endomyocardial biopsy disclosed vacuolated cardiomyocytes indicating possible Fabry disease.
Electron microscopy confirmed abundant lamellar body accumulation in cardiomyocytes.
Genetic testing validated diagnosis with identification of a heterozygous GLA variant.

Structured PICO

Population

A 42-year-old female with exertional chest discomfort, asymmetric left ventricular hypertrophy, and left ventricular outflow tract obstruction mimicking hypertrophic cardiomyopathy.

Intervention

Endomyocardial biopsy with electron microscopy and subsequent genetic testing.

Outcome

Diagnosis of Fabry disease.

Electron microscopy of endomyocardial biopsy can be crucial for diagnosing Fabry disease in patients presenting with asymmetric LVH and LVOT obstruction mimicking hypertrophic cardiomyopathy.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

Fabry disease, characterized by α-galactosidase A (GLA) deficiency, causes left ventricular hypertrophy (LVH) often mimicking hypertrophic cardiomyopathy (HCM). Differentiating Fabry disease from HCM is crucial, given their therapeutic and prognostic differences. A 42-year-old female diagnosed with HCM with left ventricular outflow tract (LVOT) obstruction was referred to our cardiology department after complaining of exertional chest discomfort. Electrocardiography showed LVH with strained ST segment. Echocardiography showed normal wall motion with asymmetric LVH and systolic anterior motion of the mitral valve with a basal LVOT resting gradient of 71 mmHg. Endomyocardial biopsy (EMB) revealed moderately vacuolated cardiomyocytes under light microscopy. Electron microscopy (EM) revealed abundant accumulation of lamellar bodies within cardiomyocytes. Although LVOT obstruction is common in HCM but rare in Fabry disease, the EMB findings suggested Fabry disease. Subsequent genetic testing identified a heterozygous p. Ala37Val (c. 110C>T) GLA variant (NM₀00169. 3), confirming the diagnosis. The patient was prescribed bisoprorol and cibenzorine, which improved her resting gradient and symptoms, and chaperon therapy was initiated. In this case, the patient's symptoms mimicked HCM with no clinical evidence of Fabry disease other than the electron microscopic findings. This case highlights the importance of EMB using EM to exclude Fabry disease when asymmetric LVH is seen.

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