Isolated mitochondrial myopathy misdiagnosed as polymyositis

Eun Hye Jeong

doi:10.15436/2377-1348.16.1117

Abstract

Mitochondrial myopathies are caused by dysfunction of the mitochondria and are systemic disorders that present with diverse clinical manifestations. They have been found to be especially prevalent in children. In this report, we present the case of a 55-year-old male patient who developed progressive symmetric proximal muscle weakness in both upper and lower extremities. Although the elevated levels of muscle enzymes and the findings of magnetic resonance imaging of lower extremities were suggestive of polymyositis, we made a final diagnosis of isolated mitochondrial myopathy based on the result of the biopsy of the thigh muscle. In this report, we emphasize the importance of performing a correct differential diagnosis of myopathies, particularly in the cases without evidence of involvement of other organs.

Highlights

Mitochondria are intracellular organelles that host the components of the respiratory chain and produce adenosine triphosphate
We report a case of isolated mitochondrial myopathy confirmed by muscle biopsy, initially misdiagnosed as polymyositis
A notable feature of muscular disorders is that they present with common clinical presentations, symptoms, and laboratory findings, which makes it important to differentiate mitochondrial myopathy, inflammatory diseases, and degenerative diseases when diagnosing and treating muscular disorders

Summary

Introduction

Mitochondria are intracellular organelles that host the components of the respiratory chain and produce adenosine triphosphate. We report a case of isolated mitochondrial myopathy confirmed by muscle biopsy, initially misdiagnosed as polymyositis. The patient showed progressive symmetric proximal muscle weakness in both extremities, so we suspected myopathy and performed nerve conduction study and electromyography (EMG).

Results

Conclusion