SESSION TITLE: Pulmonary Manifestations of Systemic Disease Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Patients who present with a periodic fevers represent a clinical puzzle to the clinician. Histiocytic necrotizing lymphadenitis or Kikuchi-Fujimoto disease (KFD) is a rare inflammatory condition that can be confused with lymphoma or tuberculous lymphadenitis. It mostly affects young females and presents with fever, fatigue, joint pain, lymphadenopathy, hepatosplenomegaly, and rashes. High ESR and anemia are common lab findings. Additionally, it is associated with lupus, infectious, inflammatory, or viral diseases. The disease course is self-limiting; however, it requires early diagnosis to avoid unnecessary testing and treatment due to its shared characteristics with more malignant pathologies. METHODS: A review of the literature was conducted. RESULTS: A 25-year-old African American woman with a history of fibroids was referred from an outpatient clinic for daily fevers of 102°F for the past month. There was an associated painful left-sided axillary lump without redness or discharge. She was given a course of Bactrim and Keflex by an urgent care clinic for presumed hidradenitis suppurativa without any improvement. She presented to the emergency department, where the initial workup was unremarkable. Admission was recommended but the patient left against medical advice but was given clindamycin for 7 days. Three weeks later, the patient presented to the ED for the same symptoms. She complained of generalized fatigue, bilateral upper extremity and abdominal rash and a 10-pound weight loss for the past month, attributed to a poor appetite. Vital signs were significant for temp 100.9°F and HR 108. Physical exam was notable for diaphoresis and a 2 x 2 cm left axillary node that was mobile and tend. Lab results were notable for ESR of 40, CRP of 74.56, and LDH of 431. A rheumatic workup was negative. CT scan of the Chest Abdomen and Pelvis showed a soft tissue mass next to the left pectoralis minor measuring 2.7 x 2.1 x 3.7 cm, possibly representing a cluster of pathologically enlarged lymph nodes. It also showed ground-glass and tree-in-bud opacities bilaterally. The patient underwent CT-guided core biopsy of the axillary mass which showed limited lymph node tissue with faintly preserved nodular pattern and necrotic areas, confirming necrotizing lymphadenitis. CONCLUSIONS: Like many clinicians who may encounter a young female presenting with periodic fevers and constitutional symptoms, malignancy, or common autoimmune diseases like sarcoid are likely high on the differential. KFD's rarity risks its confusion with malignant lymphoma. For example, one case series reviewed the lymph node biopsies of 27 patients with confirmed KFD. Only three of these were suggested by the pathologists to be KFD, while the rest were incorrectly diagnosed as non-Hodgkin’s lymphoma. CLINICAL IMPLICATIONS: Unnecessary diagnostic testing and workup are avoidable if the physician is well informed of rare diagnoses that may present. DISCLOSURES: No relevant relationships by Raheel Anwar, source=Web Response No relevant relationships by Namrita Prasad, source=Web Response