A Case of Brucellosis Associated With Histiocytic Necrotizing Lymphadenitis: A Diagnostic Pitfall

Human cases of brucellosis are rare in the United States and difficult to diagnose. We report a case of a young female who underwent a diagnostic investigation of fever of unknown origin, which included a lymph node biopsy. The biopsy was consistent with Kikuchi’s Disease, or histiocytic necrotizing lymphadenitis, an entity where the major differential diagnosis is systemic lupus erythematosus. Interestingly, serologic studies supported the diagnosis of brucellosis. Brucellosis has rarely been associated with histiocytic necrotizing lymphadenitis. This association has never been reported in the United States, thus suggesting that brucellosis should be considered in the differential for histiocytic necrotizing lymphadenitis, along with lupus-like autoimmune disease. As the prognosis and treatment of histiocytic necrotizing lymphadenitis, brucellosis, and systemic lupus erythematosus are distinct, it is important to differentiate these entities.