Fever, lymphadenopathy, and a diagnostic dilemma: a case of Kikuchi-Fujimoto disease masquerading as tuberculosis in a diabetic patient.

Kikuchi-Fujimoto disease is a rare, self-limiting autoimmune necrotizing lymphadenitis that poses unique diagnostic challenges due to vague, overlapping clinical and laboratory features with numerous important and common differential diagnoses. Accurate diagnosis is needed to avoid unnecessary and unwanted treatment. Herein, we report a unique case of a middle-aged diabetic man from South India presenting with prolonged fever, significant weight loss, and generalized lymphadenopathy. Laboratory findings revealed leukopenia, markedly elevated inflammatory markers, and a moderately positive antinuclear antibody titer, raising immediate concern for systemic lupus erythematosus. Results of an extensive infectious workup, including tuberculosis testing, were negative. The definitive diagnosis was established by lymph node biopsy demonstrating necrotizing lymphadenitis with karyorrhectic debris and crescentic histiocytes, without caseating granulomas or hematoxylin bodies. This case underscores the need for early lymph node biopsy in tuberculosis-endemic settings to avoid misdiagnosis and inappropriate antitubercular therapy and also highlights the emerging association between Kikuchi-Fujimoto disease and autoimmune serological markers.