Fig. 2

Muscle biopsy finding based on histological examination: (A) Hematoxylin and eosin (H&E) stain: musculature seen transversely and obliquely, preserved fascicle structure; perimysial connective tissue proliferation, no fat cell proliferation; no lymphohistiocytic cell infiltrates; muscle fibers polygonal, physiological fiber size variability, no fiber fragmentation or nuclear clumps; predominantly peripheral nuclei (centrally located nuclei <3%). No cell necrosis or basophil regenerating fibers; no ragged red fibers; no intracellular glycogen or lipid proliferation. (B) Modified Gomori stain shows occasionally the enrichment of mitochondria subsarcolemmally (white arrows). (C) Nicotinamide adenine dinucleotide hydrogen (NADH) stain shows increased subsarcolemmal reactivity in a minority of fibers (white arrows). (D) Periodic acid–Schiff (PAS) stain shows increased sarcoplasmic build-up on a minority of diseased muscle fibers (white arrows). (E, F) Adenosine triphosphatase (ATPase) stain (at pH 4.3 and 9.4) shows fiber-type disproportion (increased abundance of type 2 fibers). Insets show areas of interest in greater detail.