Abstract
A 54-year-old Japanese woman presented with purpuric eruptions on both legs, associated with arthralgia and swelling of wrist, knees, and ankles bilaterally. The patient's temperature was 38.3 ℃ and laboratory investigations identified a raised erythrocyte sedimentation rate and a C-reactive protein level of 2.53 mg/dl, an increased serum rheumatoid factor (RF) level of 632.9 U/ml, and a decreased CH50 level of 25.3 U/ml. Histopathological examination of a skin biopsy from the purpuric lesion of the right lower leg revealed a perivascular neutrophil dominant inflammatory cell infiltration with leukocytoclasis, red blood cell extravasation, and fibrinoid degeneration of the small vessel walls in the upper and middle dermis, consistent with leukocytoclastic vasculitis. Rheumatoid arthritis (RA) was initially suspected, but we diagnosed our patient as human parvovirus B19 (HPaV-B19) infection from the result of a positive serum HPaV-B19 IgM antibodies level of 8.84. The symptoms of pyrexia, arthralgia, and skin lesions were resolved in 12 days with supportive measures. Recurrence was not observed thereafter, although her raised serum RF level has remained positive. HPaV-B19 infection should be kept in mind as a differential diagnosis in an adult case presenting with RA-like symptoms and atypical eruptions.
