Inflammatory Myopathy in a Case of Primary Sjögren's Syndrome on Chronic Statin Therapy: A Diagnostic Challenge and Rare Clinical Presentation.

abstractPrimary Sjögren's syndrome (pSS) is a systemic autoimmune disease primarily affecting exocrine glands, with less frequent but significant extraglandular manifestations. Among these, inflammatory myopathy (IM) is rare, particularly in biopsy-proven cases. We report the case of a 63-year-old female with a history of hypertension, type 2 diabetes mellitus, and chronic statin use who presented with progressive, symmetric proximal muscle weakness of 8 months' duration. Neurological examination revealed flaccid weakness without sensory involvement. Laboratory evaluation showed markedly elevated creatine phosphokinase levels and positive anti-HMG-CoA reductase and anti-Ro52 antibodies. Magnetic resonance imaging of the thighs demonstrated diffuse myoedema. Muscle biopsy revealed myonecrosis, myophagocytosis, and lymphocytic infiltration, consistent with IM. Schirmer's test and salivary gland biopsy confirmed the diagnosis of pSS. IM may rarely occur in pSS and can be easily overlooked in the context of long-term statin use. A high index of suspicion, combined with detailed immunologic workup and tissue biopsy, is essential for accurate diagnosis and timely immunosuppressive therapy.