Paraneoplastic Dermatomyositis in a Patient with Small Cell Bladder Cancer: A Case Report

Introduction: Dermatomyositis (DM) is an idiopathic inflammatory myopathy characterized by muscle weakness and distinctive skin manifestations.It involves both muscular and extra muscular symptoms, with an unknown etiology likely rooted in autoimmune processes. Case Presentation:We report on a 72-year-old male with hypertension and hypercholesterolemia, initially presenting with urinary symptoms and bladder tumours diagnosed as combined small cell carcinoma.After neoadjuvant chemotherapy and postcystoprostatectomy, the patient developed progressive muscle weakness, cutaneous signs of DM, and dysphagia.Laboratory tests revealed elevated creatine kinase and anti-TIF1-gamma antibodies, with MRI and nail fold capillaroscopy confirming myositis. Diagnosis and Treatment:After establishment of the diagnosis of paraneoplastic DM, the patient was treated with corticosteroids, intravenous immunoglobulins, and hydroxychloroquine, showing initial improvement.Persistent dermatitis required additional immunosuppressive therapies, including rituximab and upadacitinib. Discussion:The link between DM and cancer is well-documented, with DM patients showing significantly higher cancer risks.Our patient's case underscores the complexity of managing DM in the context of cancer, necessitating adaptable and ongoing treatment strategies. Conclusion:This case highlights the intricate interplay between DM and malignancy, demonstrating the importance of tailored therapeutic approaches to manage both muscular and cutaneous symptoms effectively.