[Dermatomyositis combined with IgA vasculitis: A case report].

Dermatomyositis (DM) is an autoimmune disease characterized by muscle involvement of the proximal extremities and specific skin involvement, like Gottron sign and heliotrope rash. HenochSchonlein purpura (IgA vasculitis) nephritis is characterized by hematuria and/or proteinuria clinically, with histologic evidence of IgA nephropathy, and also can be clinically characterized by non-thrombocytopenic purpura, presenting with petechiae and ecchymosis on the skin and mucous membranes, often involving multiple organs and systems, accompanied by abdominal pain, joint swelling and pain, and renal lesions. We reported here a patient with symmetric muscle weakness in her proximal limbs and typical Gottron sign, whose laboratory examination showed elevated creatine kinase (CK) level and myogenic damage electromyographically, which were concomitant with dermatomyositis. We applied prednisone combined with cyclophosphamide, and the patient's muscle strength, interstitial lung disease and all improved gradually. The patient gradually developed severe hepatic damage [significantly increased glutamic-pyruvic transaminase (ALT), glutamic oxalacetic transaminase (AST) and bilirubin], high fever (body temperature fluctuated between 38.0-39.2 °C), thrombocytopenia (limb distal purplish rash, some slightly protruded from the skin surface, some fused into a piece, which did not fade with pressure) and intractable diarrhea (waterlike stool, antidiarrheal drug treatment was not good), with new onset of the skin lesions on multiple areas of her body, as well as abrupt occurrence of massive proteinuria, which resulted in huge challenges in the following diagnosis and treatment. After extensive differential diagnosis from various directions, including pathological biopsies, it finally came out to be dermatomyositis combined with IgA vasculitis, which had been rarely reported. Both cellmediated immunity to muscle antigens and immune-complex disease might participate in the pathogenesis. There was evidence that they were immune complex diseases. Several immune mechanisms played an important role in the pathogenesis of both DM and IgA vasculitis. We conducted a substantial literature review of the above diseases. The purpose of our study is to strengthen the clinical understanding of such complicated diseases, and to highlight the importance of pathological biopsy in the diagnosis (renal biopsy pathology gave us a definite diagnosis). And what is more important is that seizing the opportunity to initiate treatment can control the disease and improve the prognosis.