Microscopic polyangiitis initiated with liver dysfunction, calf pain and fever of unknown origin.

We report herein a case of microscopic polyangiitis (MPA), presenting onset with a spiking fever, liver/biliary dysfunction without jaundice and calf pain without elevation of serum creatine phosphokinase. During 1 month of careful examinations for initial diagnosis, the patient developed renal dysfunction and pulmonary hemorrhage. Based on the results of positive MPO-ANCA, renal and pulmonary involvements, the patient was diagnosed with MPA and treated with high-dose prednisolone and oral cyclophosphamide. Soon after initiation of the treatment, symptoms such as fever, calf pain, liver/biliary dysfunction and renal dysfunction disappeared with decrease of MPO-ANCA titer to the normal level.