Emery-Dreifuss Muscular Dystrophy Gomori trichrome-stained frozen section Necrotic fiber Variation in fiber size with many hypertrophic fibers Increase in endomysial connective tissue Nonspecific so-called dystrophic changes seen in many of the muscular dystrophies. Can also be seen in any chronic myopathic disorder. This disorder is due to loss of the protein emerin.
H & E, paraffin The excess of internalized nuclei can lead to nuclear chains.
Myotonic Dystrophy NADH-reacted section Ring fibers in which myofilaments are organized in different directions
Fascioscapulohumeral Dystrophy (FSHD) The majority of dystrophies do not have a specific histopathologic appearance. Clinical features are also very important. For example, winging of the scapula is characteristic of FSHD.
FSH Dystrophy Variable non-specific changes Range from scattered atrophy to “dystrophic” features. Inflammation can be present.
Basophilic subsarcolemmal structures are sarcoplasmic masses. Sometimes occur in chronic myopathies such as FSH and myotonic dystrophy.
Sarcoplasmic Masses Stained darkly with NADH reaction
Oculopharyngeal Muscular Dystrophy (OPD) Variation in muscle fiber size with atrophic angulated fibers Sometimes contain rimmed vacuoles
Higher power view of Gomori trichrome-stained section Angulated fibers Fiber containing a large rimmed vacuole
Oculopharyngeal Dystrophy Gomori trichrome Ragged red fibers are sometimes seen. Characteristic of proliferation of abnormal mitochondria.
May be identified by electron microscopy in OPD Intranuclear Filamentous Inclusions
Central areas of absent staining in the dark type I fibers Mitochondria absent Congenital Myopathies: Central Core Myopathy NADH
The core consists of disorganized myofibrils and the area is devoid of mitochondria.
Congenital Fiber Type Disproportion H&E Bimodal size population
Smaller fibers are type I More numerous Stain lightly Larger or normal fibers are type II Congenital Fiber Type Disproportion ATPase pH 4.3