Kikuchi-Fujimoto disease mimicking hemophagocytic lymphohistiocytosis in a young white male: a case report.

backgroundKikuchi-Fujimoto disease (KFD) is a rare, generally self-limiting cause of necrotizing lymphadenitis, predominantly affecting young women of East Asian descent, and uncommon in Western populations. Although usually benign, KFD can rarely present with systemic inflammatory features that overlap with hemophagocytic lymphohistiocytosis (HLH), creating significant diagnostic uncertainty and risk of misdiagnosis. CASE PRESENTATION: We report the case of a 23-year-old white male in the United Kingdom who presented with a two-week history of intermittent fever, significant unintentional weight loss, posterior cervical lymphadenopathy, and poor dentition. Laboratory investigations demonstrated leukopenia with neutropenia and lymphopenia, mild transaminitis, and marked hyperferritinemia (8757 µg/L). Extensive infectious, autoimmune, and malignant workup was negative. Imaging revealed isolated cervical lymphadenopathy without disseminated disease. Bone marrow aspirate and trephine biopsy showed hypocellularity with hemophagocytosis, raising concern for HLH. However, only four of eight HLH-2004 criteria were met, insufficient for reaching a diagnosis. Excisional lymph node biopsy demonstrated necrotizing histiocytic lymphadenitis with abundant karyorrhectic debris and crescentic histiocytes, consistent with KFD. Following multidisciplinary team discussion, the patient was treated with a short course of oral corticosteroids, resulting in rapid clinical and biochemical improvement, and no evidence of relapse or complications on follow-up.

conclusionThis case highlights an atypical presentation of KFD in a young white male in a non-endemic setting, complicated by marked hyperferritinemia and HLH-like features. It underscores the importance of a structured, multidisciplinary approach in integrating laboratory trends, marrow findings, and definitive histopathological confirmation to distinguish KFD with HLH-like features from true HLH. Awareness of such presentations is essential to avoid unnecessarily aggressive immunosuppression while ensuring timely and appropriate management.