Histologic examination revealed an intense perivascular and interstitial infiltrate of lymphocytes, histiocytes, and eosinophils with scattered granulomas, formed by histiocytes and multinucleated giant cells, palisading around collagen bundles. A medium-sized blood vessel showed inflammatory cells within its wall, fibrin deposition, and erythrocyte extravasation, consistent with vasculitis. Further laboratory evaluation showed an elevated rheumatoid factor of 595 U and elevated total IgE level of 1389 U, and was negative for antineutrophil cytoplasmic antibodies. A chest radiograph showed bilateral pulmonary infiltrates. Electromyography confirmed a bilateral sensory neuropathy. Treatment with prednisone was initiated at a dose of 1 mg/kg/d. The addition of mycophenolate mofetil failed to result in remission of her disease, and initiation of cyclophosphamide therapy is planned.