A case of femoral hemorrhage in a patient with microscopic polyangiitis with low levels of myeloperoxidase-antineutrophil cytoplasmic autoantibody.

We present the case of a 67-year-old female with femoral hemorrhage accompanied by microscopic polyangiitis. She was admitted to our hospital with symptoms of general fatigue, fever, and edema of the lower limbs. She was diagnosed with microscopic polyangiitis on the basis of the cardinal symptoms of the condition, including rapidly progressive glomerulonephritis and the presence of myeloperoxidase-antineutrophil cytoplasmic autoantibody (MPO-ANCA), albeit at a low titer. Renal biopsy demonstrated the presence of fibrocellular crescent-shaped glomeruli with interstitial infiltration. No immune deposits were detected in immunofluorescence studies. The patient was treated with steroids and anti-platelet agents; subsequently, the inflammatory reaction subsided and MPO-ANCA and C-reactive protein titers decreased. However, on day 14, the patient experienced sudden onset of swelling in the left femoral region accompanied by hypotension. Her hemoglobin level dropped from 8.8 to 4.5 g/dl in the subsequent hours. Although computed tomography of the legs revealed an extensive hematoma in the left quadriceps femoris muscle, the patient recovered after receiving a transfusion and supportive therapy with discontinuation of dipyridamole. Thereafter, her renal function improved, and she was discharged. To our knowledge, this is the first report of a case of microscopic polyangiitis accompanied by femoral hemorrhage.