PMC9541118_01
Preoperative transthoracic echocardiogram. (A) Transthoracic echocardiogram without contrast and (B, C) with intravenous contrast-enhancing agent. (B) Parasternal long axis view demonstrating asymmetric septal thickening/mass with contrast enhancement and (C) protrusion of the mass into the right ventricular outflow tract on parasternal short axis.
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F1
Transthoracic echocardiogram revealed a prominent thickening at the base of the interventricular septum that extended into the right ventricular outflow tract (RVOT) (Figure 1 A-C).
Preoperative cardiac imaging. Magnetic resonance imaging using steady state free precession cine sequence: (A) 3-chamber view, (B) short axis at the mid-level, (C), first pass perfusion, and (D) delayed enhancement after gadolinium showing a large right ventricular (RV) mass measuring 4.9 x 3.7 cm invading the RV free wall, with (E) intense first pass perfusion and significant late gadolinium enhancement cardiac computed tomography demonstrating short axis basal anteroseptal mass protruding into the RV outflow tract with central contrast enhancement and multiple septal perforator feeding vessels.
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F2
The mass was confirmed on subsequent cardiac magnetic resonance imaging, which demonstrated a 4.9 x 3.7 cm mass extending from the anterior left ventricular wall to the inferoseptum and from the base of the heart through the mid-segment as well as into the RVOT (Figure 2 A-D). Cardiac computed tomography showed a basal anteroseptal mass protruding into the RVOT with central contrast enhancement and multiple septal perforator feeding vessels (Figure 2 E).
H&E stain at increasing magnification 100x. (A) The resected lesion was composed of disorganized, hypertrophic cardiac myocytes with interstitial fibrosis. (B) There were also scattered thickened intramural arteries, dilated venules, and small collections of adipocytes 200x. (C) At intermediate magnification, the myocytes were haphazardly arranged and enlarged with sarcoplasmic vacuolation and nuclear enlargement 400x. There were scattered enlarged nuclei, some with mild hyperchromasia, irregular nuclear contours, and inconspicuous nucleoli.
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F3
Sections showed discrete lesions of marked myocyte hypertrophy with disorganization, focal scarring, and thickened intramural arteries (Figure 3 A-C).