Characterization of lymph node histology in adult onset Still's disease.

Adult onset Still's disease is an acknowledged cause of fever of unknown origin. Eight patients with adult onset Still's disease each had a lymph node biopsy as part of their initial evaluation. Seven of 8 biopsies exhibited intense, somewhat atypical, paracortical immunoblastic hyperplasia. This nodal histology, while not specific for the disorder, appears distinct from that associated with rheumatoid arthritis, Sjögren's syndrome, and systemic lupus erythematosus. This paracortical cellular proliferation with apparent nodal effacement, along with atypical immunoblasts, can simulate lymphoma. Adult onset Still's disease should be added to the differential consideration of benign lymph node histology simulating lymphoma.