Hyaline body myopathy: Adulthood manifestations

Background: Hyaline body myopathy (HBM) is a rare chronic nonprogressive congenital myopathy, with variable patterns of inheritance. Methods: We describe a patient with congenital HBM with progression of weakness and increasing muscle pain in adulthood. Three muscle biopsies, done at various times in her life, are reported. Results: Symptoms started during childhood; however, as an adult, following a period of stability with no progression of the disease, the patient became symptomatic with worsening proximal limb weakness, severe aching pain and hypertrophy of calves. Moderate elevations of serum creatine kinase and myopathic features were noted on electrophysiologic testing. Muscle pathology showed significant fatty infiltration of skeletal muscle and increased number of fibers with internal nuclei. Histology demonstrated the presence of subsarcolemmal, well-delineated hyaline areas, which on histochemical studies was shown to be limited to type I fibers. The hyaline bodies were dark with pH 4.2 ATPase and with immunohistochemical studies reacted only with myosin heavy chain slow. Electron microscopy showed the hyaline bodies to be composed of nonmembrane bound, fairly even sized granular material, which merged with the adjacent myofibrils. Earlier muscle biopsies, done during childhood, also revealed presence of similar subsarcolemmal hyaline deposits. Conclusion: There appears to be a pattern of presentation with adulthood progression in HBM, which has not been described before. Further case studies are required to understand the clinical progression in HBM.