Immune Myositis Complicating Follicular Lymphoma: Case Report.

Background and Clinical Significance: Idiopathic inflammatory myopathies are a heterogeneous group of autoimmune disorders that may present as paraneoplastic syndromes. Although most frequently associated with solid-organ malignancies, hematological neoplasia, particularly lymphomas, is also likely linked. Case Presentation: We describe a sexagenarian female with progressive proximal muscle weakness, myalgias, and lymphadenopathy. Laboratory evaluation revealed markedly elevated creatine phosphokinase and myositis-specific antibodies: anti-Mi-2α and anti-EJ. Magnetic resonance imaging of the thighs confirmed active myositis. Lymph node biopsy reported follicular lymphoma. The patient was initiated on methotrexate and rituximab, with which she reported significant symptomatic relief. Conclusions: Inflammatory myopathy is an exceedingly rare presentation of follicular lymphoma. This case emphasizes that lymphomas can closely mimic other disease processes and present significant diagnostic challenges, and they should be included in the differential diagnosis of myopathies. Improved awareness and early diagnosis of lymphoproliferative neoplasia often yield better overall clinical outcomes.