We herein report a rare case of intravascular large B-cell lymphoma (IVLBL) that developed during treatment of antineutrophil cytoplasmic antibody-associated vasculitis (AAV). A 77-year-old woman presented with elevated lactate dehydrogenase levels and pancytopenia. The patient did not have a fever. Elevation of soluble IL-2 receptors without lymphadenopathy raised suspicion of IVLBL. The diagnosis was confirmed by a random skin biopsy, but the patient was refractory to therapy and died. Our case highlights potential complications of AAV with IVLBL. Patients with IVLBL, particularly after receiving immunosuppressive agents, may not exhibit a fever and may have a poor prognosis owing to acquired resistance to chemotherapy.
Keywords: ANCA-associated vasculitis; autoimmune disease; intravascular large B-cell lymphoma; pancytopenia.