Comparison of muscle pathology in riboflavin-responsive lipid storage myopathy before and after treatment: one case report and review of literature

Objective To study the muscular pathological characteristics in riboflavin-responsive lipid storage myopathy before and after treatment. Methods A 10-year follow-up visit was made on a patient with riboflavin-responsive lipid storage myopathy, and the changes of serum enzymes, and both histological and ultrastructural data acquired by general muscular pathology, immunohistochemistry and electron microscope were observed before and after treatment by using levocarnitine. ETFDH gene were detected in the patient and his family. Results The patient presented limb weakness, difficulty in raising head and dysphagia, which were typical clinical features of lipid storage myopathy (LSM). The serum creatine kinase (CK) level and lactic dehydrogenase (LDH) level elevated evidently. EMG showed myogenic abnormality, and muscular pathology revealed numerous lipid droplets deposited in the fibers. ATPase staining showed predominant atrophy of typeⅠ fibers and relative increasing of the portion of typeⅡ fibers. Modified Gomori trichrome (MGT) staining did not observe ragged red fibers. Immunohistochemical staining showed positive expression of dystrophin. Sultan Ⅲ staining revealed multiple vacuolated myofibers. ETFDH gene test showed two heterozygous mutations in the patient. After treating with levocarnitine for several years, the patient could live a normal life. The muscular pathological result returned to normal. Conclusions After appropriate therapy, patient with lipid storage myopathy can not only gain complete remission clinically, but also the reversion of lesion pathologically.