[Case of microscopic polyangiitis and giant cell arteritis after influenza vaccination]

We report a case of microscopic polyangiitis (mPA) and giant cell arteritis (GCA) (polyangiitis overlap syndrome) after influenza vaccination. A 67-year-old female with chronic kidney disease, who had been observed by a physician, presented fever and headache after immunization of influenza vaccine. She was diagnosed as having with mPA and GCA based on symptoms, worsening of renal function, biopsy of temporal artery (giant cell arteritis) and skin (microscopic polyangiitis), pulmonary involvement and the presence of myeloperoxidase-specific anti-neutrophil cytoplasmic antibodies (MPO-ANCA). She was treated with prednisolone (PSL) and the symptoms were improved. However, two months later she was presented with general physical weariness. She was diagnosed as having with pneumocystis pneumonia, cytomegalovirus infection and cryptococcosis. Despite intensive treatment, she was died and autopsy was performed. The present case suggests that the influenza vaccination may cause different types of vasculitis, mPA and GCA, through the common mechanism in pathophysiology. This patient is also the first case of mPA and GCA proven by histological examination.