A case of anti-Mi-2 antibody-positive dermatomyositis associated with malignant lymphoma

Dermatomyositis is a systemic idiopathic inflammatory myopathy often associated with internal malignancy and/or interstitial lung disease. The clinical phenotype of dermatomyositis depends on the presence of myositis-specific autoantibodies in the serum. We present a case of a 64-year-old woman who developed symmetrical muscle weakness. Systemic PET-CT showed an accumulation of fluorine 18 fluorodeoxyglucose in the mesenteric and para-aortic lymph nodes, indicating their swelling. Biopsy specimen with peritonectomy showed follicular lymphoma (Grade 2, clinical stage II). Chemotherapy and systemic corticosteroids improved clinical manifestations. Her serum was later found to be positive for anti-Mi-2 antibody by enzyme-linked immunosorbent assay and immunoprecipitation. The association of anti-Mi-2 antibody positive dermatomyositis with malignant lymphoma is rare and has seldom been reported in the English literature.