The great masquerader: Kikuchi-Fujimoto disease presenting as fever of unknown origin

Abstract

Introduction: Kikuchi-Fujimoto (KF) disease, also known as necrotizing histiocytic lymphadenitis, is a rare cause of fever of unknown origin. Most commonly seen in Japanese populations, it presents with fever and diffuse lymphadenopathy. KF can present a diagnostic challenge as its presentation can mimic sepsis, autoimmune disease, and/or malignancy. We present a case of KF disease presenting with innumerable pulmonary nodules and suspected sepsis.

Case report: A 24-year old African-American male inmate with no past medical history presented to the Emergency Department with two witnessed generalized tonic-clonic seizures. Initial vitals were notable for a fever of 101.5 F, tachycardia, and tachypnea. He was lethargic with a diffuse, erythematous, scaly, necrotic rash. Additionally, cervical, axillary, and inguinal mobile, non-tender lymph nodes were noted. Laboratory studies revealed white blood cells 1.9 × 10 3 cells/μL with 25% bands, hemoglobin 9.4 G/dL, and platelet count of 110 × 10 3 cells/μL. He was subsequently admitted for sepsis due to presumed meningitis and started on broad-spectrum antibiotics. Lumbar puncture revealed no pleocytosis. Peripheral blood smear showed bandemia with Pelger Huet cells. Computed Tomography of chest, abdomen, and pelvis with contrast revealed diffuse pulmonary nodules involving all lobes of the lungs in addition to bulky hilar and retroperitoneal lymphadenopathy. Interventional Radiology performed a retroperitoneal lymph nodes biopsy that revealed lymphoplasmacytic cell infiltrate with extensive necrosis. Otolaryngology performed an excisional biopsy of a lymph node, which showed histiocytic necrotizing lymphadenitis. The final diagnosis was Kikuchi-Fujimoto disease, also known as histiocytic necrotizing lymphadenitis.

Outcome: The patient completed a 7-day course of empiric antibiotics. Workup for infectious etiologies was negative. The patient had a repeat CT of the chest with interval resolution of his pulmonary nodules on outpatient follow-up.

Conclusion: Patients with innumerable pulmonary nodules and fever of unknown origin should be evaluated early in their hospital course for KF as early diagnosis can reduce excessive testing and shorten hospital stay.

Keywords: Kikuchi-Fujimoto disease; Pulmonary nodule.