Mass-like hypertrophic cardiomyopathy
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Mass-like or tumefactive hypertrophic cardiomyopathy is a morphological variant or phenotype of hypertrophic cardiomyopathy (HCM).
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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:
- cine imaging: focal mass-like thickening
- cardiac strain imaging: variable contractility
cardiac tissue characterization
- T2/STIR black blood: should look like normal myocardium
- T1 mapping: mildly increased native T1 values
- ECV: mildly increased
- perfusion imaging: normal first-pass perfusion
- fan-shaped or patchy mesocardial late gadolinium enhancement
- indicating replacement fibrosis or myocardial scarring
The radiological report should include a description of the following:
- location, extent, contractility and contrast enhancement of the hypertrophic wall segment
- cardiac volumes and measurements including left ventricular mass
- cardiac wall motion abnormalities
- presence of myocardial crypts
- signs of myocardial fibrosis, focal replacement fibrosis or myocardial fiber disarray
- mitral annular plane systolic excursion (MAPSE)
- left ventricular outflow obstruction
- systolic anterior movement of the mitral valve
Conditions that might mimic the clinical presentation or imaging appearance of mass-like or tumefactive hypertrophic cardiomyopathy include 1-5:
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- 2. Hansen M & Merchant N. MRI of Hypertrophic Cardiomyopathy: Part I, MRI Appearances. AJR Am J Roentgenol. 2007;189(6):1335-43. doi:10.2214/ajr.07.2286 - Pubmed
- 3. Fattal J, Henry M, Ou S et al. Magnetic Resonance Imaging of Hypertrophic Cardiomyopathy: Beyond Left Ventricular Wall Thickness. Can Assoc Radiol J. 2015;66(1):71-8. doi:10.1016/j.carj.2014.07.005 - Pubmed
- 4. Shuroog J, Canakis J, Khan F, Suryanarayana P, Soherwardi S. A Rare Case of Mass-Like Hypertrophic Cardiomyopathy. Cureus. 2021;13(1):e12787. doi:10.7759/cureus.12787 - Pubmed
- 5. Dillman J, Mueller G, Attili A, Dorfman A, Ensing G, Gordon D. Case 153: Atypical Tumefactive Hypertrophic Cardiomyopathy. Radiology. 2010;254(1):310-3. doi:10.1148/radiol.2541082143 - Pubmed
- 6. Noureldin R, Liu S, Nacif M et al. The Diagnosis of Hypertrophic Cardiomyopathy by Cardiovascular Magnetic Resonance. J Cardiovasc Magn Reson. 2012;14(1):17. doi:10.1186/1532-429x-14-17 - Pubmed