A50-51 Kikuchi-Fujimoto Disease: A Diagnostic Mimic of Lymphoma and Sepsis

Rationale Kikuchi-Fujimoto Disease (KFD), or histiocytic necrotizing lymphadenitis, is a rare self-limited inflammatory disorder. It presents with fever, leukopenia, & necrotizing lymphadenopathy. Its clinical and radiologic profile can closely mimic sepsis, lymphoma, or hemophagocytic syndromes, exposing patients to unnecessary antimicrobial or cytotoxic therapy. Pulmonary and critical care physicians frequently encounter such patients during evaluation of systemic inflammatory response. Recognition of this benign yet deceptive entity is essential to prevent overtreatment and ensure accurate diagnosis. Methods We present such a case and supplement with a structured literature review using PubMed, Scopus, and Google Scholar through April 2025. Search terms included “Kikuchi-Fujimoto disease,” “histiocytic necrotizing lymphadenitis,” “lymphoma mimic,” “Kikuchi pathology,” and “diagnosis.” Systematic reviews, large case series, and seminal pathology reports were analyzed (Kucukardali et al., Clin Rheumatol 2007; Tsang et al., Am J Surg Pathol 1994; Bosch et al., Am J Clin Pathol 2004) emphasizing clinicopathologic and imaging distinctions relevant to critical care and oncology. Results A 46 -year-old woman presented with three weeks of high fevers, drenching night sweats, anorexia, and weight loss. CT and PET/CT demonstrated intensely FDG-avid cervical and supraclavicular lymphadenopathy with clinical concern for lymphoma. Laboratory evaluation revealed severe leukopenia and elevated ESR. Excisional biopsy showed patchy paracortical necrosis with karyorrhectic debris, crescentic histiocytes, and numerous CD123-positive plasmacytoid dendritic cells, with absence of neutrophils and plasma cells: findings diagnostic of KFD. She was started on prednisone 0.5 mg/kg/day, resulting in rapid resolution of fever and lymphadenopathy within two weeks. Synthesis of 400 reported cases demonstrates that KFD predominantly affects young women (mean age ≈ 30 years). Histology reveals a CD8+ T-cell and histiocyte-predominant infiltrate with paracortical necrosis and karyorrhexis mediated by a type I interferon response. Treatment is supportive, with corticosteroids reserved for severe or relapsing cases. Prognosis is excellent, with spontaneous resolution in 1 to 6 months, recurrence ≈ 3-7%, & later SLE development ≈ 13%. Conclusions KFD represents a critical benign mimic of sepsis and lymphoma that can present with constitutional “B” symptoms and radiographic findings indistinguishable from malignancy. Histopathologic recognition of its triad (paracortical necrosis with karyorrhexis, CD123+ plasmacytoid dendritic cells, and paucity of neutrophils and plasma cells) transforms management from oncologic or infectious therapy to short-course corticosteroids with complete recovery. Awareness of this diagnostic enigma among pulmonary and critical care physicians prevents unnecessary treatment and facilitates appropriate follow-up for autoimmune evolution.