A 4–year–old Hispanic male presented to the emergency department (ED) with 4 weeks of fever and increasing cervical lymphadenopathy. His mother reported daily fevers of approximately 38.3°C with neck pain and swelling. He was seen by his pediatrician on day 5 of fever, and given 3 days of IM followed by 5 days of oral antibiotics for likely bacterial lymphadenitis; symptoms persisted. After two 2 weeks of fever, he presented to the ED and was discharged with a presumed diagnosis of infectious mononucleosis. After 1 month of fever, he returned to the ED and was admitted for further work–up. He had fatigue but no weight loss, night sweats, change in appetite, dysphasia, rash, oral, extremity or ocular changes, sick contacts, recent travel or pet exposure. Fevers persisted >=38.5°C. Physical exam revealed multiple enlarged cervical and submandibular lymph nodes, left greater than right (largest measuring 4 cm) with rare small axillary and inguinal lymph nodes, and a palpable spleen tip. Laboratory analysis revealed pancytopenia, and elevated inflammatory markers (ESR, CRP and ferritin). Infectious workup including HIV, PPD, CMV, EBV, bartonella and toxoplasma was negative. Neck CT showed multiple abnormally enlarged homogeneously enhancing lymph nodes, suggestive of lymphoma. CT of chest, abdomen and pelvis showed no significant lymphadenopathy. Fine needle aspiration revealed mixed lymphoid cells with many macrophages and epithelioid histiocytes with background necrosis, indicative of a reactive process. Bone marrow biopsy revealed hypocellular marrow with reduced trilineage hematopoiesis, but no evidence of leukemia or lymphoma. Excisional node biopsy showed necrotizing lymphohistiocytic lymphadenitis diagnostic of Kikuchi–Fujimoto disease (KFD). He was discharged with a diagnosis of KFD with supportive care. One week after discharge, fevers had resolved and lymphadenopathy had significantly improved.
Kikuchi–Fujimoto disease, or necrotizing histiocytic lymphadenitis, intially described in Japan in the early 1970s, is rare and typically occurs in young women under the age of 30. It has been reported in patients as young at 2 years, but the exact frequency in children is unknown. It is generally a self–limited condition characterized by painful cervical lymphadenopathy and fever. The most common signs and symptoms associated with KFD are lymphadenopathy, fever, rash, fatigue, and joint pain. Common laboratory findings include leucopenia, anemia and elevated inflammatory markers. KFD may be difficult to diagnose, as it can mimic tuberculosis, lymphoma, and other malignancies. Lymph node biopsy is diagnostic. No etiology is currently known; however, there is an association with systemic lupus erythematosus. Most patients improve within 6 months.
Kikuchi–Fujimoto disease is rare in the younger pediatric population, however it should be considered in a persistently febrile child with painful lymphadenitis.