[Not just frailty-Sjögren's syndrome and polymyositis with mitochondrial pathology]

Sjögren's syndrome (SjS) is a systemic autoimmune disease classified among the group of connective tissue diseases that is characterized not only by classical sicca symptoms but also by extraglandular manifestations. Muscular involvement is rare; however, several case reports and studies have described an association between SjS and inclusion body myositis (IBM). Polymyositis with mitochondrial pathology (PM-Mito) is another myositis subtype linked to SjS, featuring mitochondrial changes and often considered part of the IBM spectrum.

We report the case of a 90-year-old female patient who presented with progressive dysphagia, weight loss and ultimately a progressive limitation in walking. During the diagnostic work-up, a primary SjS was diagnosed and a muscle biopsy enabled the diagnosis of PM-Mito.

This case report highlights the importance of considering neuromuscular involvement as a differential diagnosis in patients with SjS. The comorbid occurrence of myositis with mitochondrial pathology (PM-Mito or IBM) and SjS supports ongoing discussions about similar pathomechanistic aspects. Additionally, the report underlines the crucial role of a histopathological evaluation in cases of initially unclear myopathy as the key element for a correct diagnosis.