A: Hematoxylin and Eosin stain shows increased fiber size variability with scattered rounded smaller than expected fibers for patient age (<10 μm in diameter) alternating with normal-sized to larger than expected fibers for age (up to ~40μm in diameter); the normal fiber size range for patient age is 13 to 19 μm in diameter.
B: Gomori Trichrome stain shows no suggestion of any abnormal inclusions, architectural disarray or abnormal structures (rods, cores, caps, or cytoplasmic bodies) and no evidence of any possible increase in subsarcolemmal mitochondria.
C: ATPase pH 4.2 stain shows the darker staining type 1 fibers (55% of fibers in this image as quantified using ImageJ software are significantly smaller (hypotrophic appearing) overall, compared to the more normal to hypertrophic type 2 fibers which appear generally up to about twice as large. Notably, the small fibers have retained a polygonal shape and are not angular, consistent with hypoplasia rather than atrophy.