Inclusion Body Myositis; in the Differential Diagnosis of Other Inflammator Muscles Diseases

Incusion body myositis (IBM), a condition characterized by progressive muscle weakness and inclusion bodies visible on muscle biopsy, is themost common type of myopathy in patients over 50 years of age. However, it is not only underdiagnosed but frequently misdiagnosed as polymyositis and hence wrongly treated with steriods. Treatment-resistant polymyositis in patients over 50 years of age is often IBM.Case Presentation: An 58-year-old male, presented with progressive painless weaknesses and atrophy on both forearms, hands and lower extremities for 3 years ago. Two years earlier, he had been independent but now required assistance for most activities of daily living such as transfers from bed to chair, climbing stair and toileting. Family history was negative. In medical history ,6 months later he was treated by corticosteroid but suddenly exacerbated the symptoms and showed an inappropriate response. In Neurological examination he had no sensory abnormalities. Deep tendon reflexes were decreased and force reduced in upper and lower limbs in proximal and distal, especially in flexor digital and quadriceps muscles. CPK and LDH were 2504/380 IU/L and Aldolase :7.7, Anti HTLV and muscle PCR were positive other laboratory findings were within normal limits. EMG revealed fibrillation and myotonic discharge at rest and low amplitude motor unit potential with early recruitment. The result of EMG suggested myopathy with inflammation (Irritable myopathy). Biopsy from the left biceps muscle was done. pathological findings were, severe inflammatory myopathy with RED-RIMMED vacuoles and rare congophilic inclusions associated with some ragged red fibers and endomysial fibrosis as well as adipose tissues replacement compatible with inclusion body myositis. The patient was treated with IVIG, responed to treatment with IVIG was minimal improvemented weakness of upper extremities butweakness of lower limbs remained.