Subacute necrotizing lymphadenitis or Kikuchi–Fujimoto disease is a benign pathological entity diagnosed chiefly in young adults. We report a case in a 20-year-old woman who presented with swollen lymph nodes and a fever. Disseminated lymphadenopathy with nodes measuring up to 6 cm in diameter was found upon physical examination. The erythrocyte sedimentation rate was elevated to 40 mm/h and the lactic dehydrogenase level to 593 IU/l. Findings were negative from serological tests for rubella, hepatitis B, hepatitis C, HIV, and toxoplasmosis, as well as from tests for tuberculosis. A biopsy of a cervical lymph node showed nonsuppurative necrosis, karyorrhexis, and a marked histiocytic reaction consistent with Kikuchi–Fujimoto disease. No treatment was given, and a full recovery was achieved within 3 months. In this patient, the disseminated lymphadenopathy and constitutional symptoms strongly suggested a hematological malignancy and more specifically a lymphoproliferative disease.