Angioimmunoblastic lymphadenopathy often begins with constitutional symptoms, such as fever, malaise, and weight loss. Most patients have generalized lymphadenopathy, and about 40 per cent have skin lesions with maculopapular erythema, purpura, urticaria, or exfoliative erythroderma. Lymph-node biopsy specimens demonstrate the most characteristic histopathologic features: extensive effacement of lymph nodal architecture; a pleomorphic population of immunoblasts, plasma cells, lymphocytes, and eosinophils; interstitial deposits of eosinophilic material; and prominent vascular proliferation, with "arborization" of small vessels. The pathogenesis of angioimmunoblastic lymphadenopathy is still unknown, but its histopathologic features and laboratory findings strongly suggest that it is an immunologically mediated disorder. Some clinical and laboratory evidence supports the possibility that angioimmunoblastic lymphadenopathy is a benign reactive or proliferative process, whereas other studies suggest that it might be a malignant disease. In some patients, it can develop into immunoblastic sarcoma or other types of malignant lymphoma or leukemia. It is probably reasonable to consider angioimmunoblastic lymphadenopathy a prelymphomatous state of immunoblastic sarcoma.