PMC7724079_01
Severe cardiomyopathy. Left ventricular ejection fraction was calculated at 10-20%. Right ventricular ejection fraction was normal. There is no myocardial fibrosis or enhancement.
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F1
Cardiac MRI confirmed those findings; there was no valvular disease and no late gadolinium enhancement (Figure 1).
Deltoid muscle biopsy, transverse sections. (A) Hematoxylin and Eosin (H&E) stain, 10x. Note the presence of multiple fibers at different stages of necrosis (transparent arrows), regenerating basophilic fibers (solid arrow) and lymphocytic inflammation in perimysium surrounding a blood vessel (arrowhead). (B) Acid phosphatase stain, 4x. Note necrotic fibers (transparent arrows) and perimysial histiocytic inflammation (arrowhead). (C) CD4 stain, 10x. Note mild endomysial (arrowhead) and perivascular (arrow) staining. (D) CD8 stain, 10x. Scattered positive endomysial cellularity. (E) CD68, 10x. Note prominent expression in necrotic fibers (arrowheads) and perimysial/perivascular regions (arrow). CD20 staining was negative (not shown).
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F2
A deltoid muscle biopsy revealed multifocal fiber necrosis and regeneration, with occasional foci of perimysial and perivascular inflammation, which was consistent with the diagnosis of acute necrotizing myopathy (Figure 2).