Clinical case of a patient with mitochondrial myopathy – diagnostic and therapeutic challenges

Mitochondrial myopathies are a heterogeneous group of hereditary neuromuscular disorders in which pathogenic alterations in mitochondrial or nuclear DNA impair oxidative phosphorylation. The clinical spectrum is broad and frequently includes multisystem involvement, such as muscle weakness, sensorineural hearing loss, cardiac manifestations, and neurological symptoms. Due to the overlap of these features with autoimmune myositis, establishing the correct diagnosis presents a signifi cant challenge in rheumatologic practice. We report the case of a 54-year-old woman with progressive proximal muscle weakness, myalgia, and sudden bilateral sensorineural hearing loss, initially suggestive of autoimmune myositis. Paraclinical investigations demonstrated elevated muscle enzymes, a myopathic pattern on electromyography, and a chronic infl ammatory infi ltrate on muscle biopsy. Molecular-genetic testing revealed a heteroplasmic MT-TK m.8344A>G mutation, confi rming the diagnosis of mitochondrial myopathy. This case highlights the role of genetic evaluation in patients with multisystem symptoms and its importance in avoiding unnecessary immunosuppressive therapy.