Clinical and Pathological Features of Lipid Storage Myopathy

Objective To investigate the clinical and pathological features of Lipid storage myopathy(LSM).Methods The clinical data of the 4 cases of LSM were analyzed,and muscle biopsies were done with routine histological and histochemical staining.Light and electron microscopic studies were performed.Results Weakness of the proximal limb muscles and fatigue were the prominent clinical manifestations.In mort of cases,atrophy was not significant,serum muscle enzymes were slightly or moderately elevated,and EMG presented myogenic features.Myopatholoical changes showed many vacuoles in the muscle fibers,especially in the type Ⅰ fibers,with ORO staining positive.Electron microscopic observation demonstrated excessive accumulation of lipid droplets and with abnormal mitochondria in some cases.They had dramatic responses to corticosteroid or carnitine or vitamin B_2 therapy.Conclusion LSM is a rare myopathy.Weakness of the proximal limb muscles and fatigue are the prominent clinical manifestations.It is often misdiagnosed for long time.The definite diagnosis of this disease depended on muscle biopsy.