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. 2021 Feb 2;11:616075. doi: 10.3389/fneur.2020.616075

Figure 1.

Figure 1

Muscle biopsy findings. Muscle frozen sections stained with hematoxylin and eosin (H&E) (A,G); ATPase at pH 4.3 (B); modified trichrome (C); acid phosphatase (D–F); non-specific esterase (H); and periodic acid Schiff (I). CQ/HCQ myopathy is characterized by the presence of rimmed vacuoles, some of which contain granular material, and increased acid phosphatase reactivity. The vacuoles (arrows) may be of a small size (A), or large occupying the majority of the muscle fiber (B), or fibers may harbor multiple vacuoles of various sizes (C). Rarely, vacuoles may be slit-like (D), also shown in H&E in the top right corner. Vacuoles occur in both type 1 and type 2 fibers (B), but more commonly in type 1. Increased acid phosphatase reactivity may occur in a punctate fashion (“measles” appearance) (D), within vacuoles (E), or both (F). Occasionally, a mild inflammatory reaction may be present (arrowhead) either in the endomysium (G) or perimysium. Some of the vacuoles may display increased non-specific esterase reactivity (H), or glycogen accumulation (I). Scale bar: (A), 20 μm; (B–I), 50 μm. CQ, chloroquine; HCQ, hydroxychloroquine.