Mass-like hypertrophic cardiomyopathy

Last revised by Joachim Feger on 17 Dec 2021

Mass-like or tumefactive hypertrophic cardiomyopathy is a morphological variant or phenotype of hypertrophic cardiomyopathy (HCM).

Mass-like or tumefactive hypertrophic cardiomyopathy is rare and accounts for less than 2% of cases 1-4.

Mass-like or tumefactive hypertrophic cardiomyopathy can be sometimes associated with left ventricular outflow obstruction if the affected segment is located in the basal region near the left ventricular outflow tract 1.

This phenotype is characterized by asymmetric focal left ventricular thickening simulating a cardiac tumor but with otherwise typical features of hypertrophic cardiomyopathy.

Microscopically the hypertrophic segment is characterized by the following features 1:

  • cardiomyocyte hypertrophy
  • myocardial fiber disarray
  • interstitial fibrosis or replacement fibrosis
  • bizarre enlarged nuclei nuclear hyperchromasia and pleomorphism

Mass-like hypertrophic cardiomyopathy is characterized by a focally thickened segment.

Echocardiography might serve as a first-line imaging modality for the detection of the lesion 4.

Speckle tracking echocardiography can be used to assess cardiac contractility which might be variable but should be present.

On cardiac CT the cardiac segments affected by mass-like hypertrophic cardiomyopathy should look like the remainder of the myocardium with similar contrast enhancement and without calcifications 2.

Cardiac MRI characteristics of mass-like hypertrophic cardiomyopathy feature a similar signal intensity as the normal uninvolved myocardium and relative preservation of myocardial contractility unlike real cardiac tumors which need to be distinguished from the condition 1-5:

The radiological report should include a description of the following:

Conditions that might mimic the clinical presentation or imaging appearance of mass-like or tumefactive hypertrophic cardiomyopathy include 1-5:

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