Fever of unknown origin and mesenteric mass: a case of kikuchi fujimoto disease and systemic lupus erythematosus

Background: Kikuchi Fujimoto Disease (KFD) is a rare autoimmune disorder manifesting with prolonged fevers and lymphadenitis. It is proposed to be triggered by infectious agents in genetically susceptible patients. Diagnosis is confirmed with lymph node biopsy. In most patients, symptoms resolve spontaneously but rarely glucocorticoids are required for remission. Clinical Summary: This is a unique case of KFD with mesenteric lymphadenitis leading to a new diagnosis of Systemic Lupus Erythematosus (SLE) in a 24-year-old African American male presenting with two weeks of epigastric pain and fever. Initial CT abdomen showed a heterogeneous soft tissue mass followed by CT guided core biopsy of mesenteric lymph nodes revealing necrotic lymphadenopathy. He was empirically treated for intraabdominal infection with antibiotics and then discharged home. A week later he was re-admitted for similar complaints. He was febrile and tachycardic. Labs showed neutropenia and elevated inflammatory markers. Infectious work up was negative. Autoimmune panel was positive for an Anti-Nucleic Acid (ANA), Ribonucleoprotein (RNP), Smooth Muscle (SM) Antibodies and Urine Protein: Creatinine Ratio (UPCR) of 0.5 gr and 1.2 gron two separate occasions. He was treated empirically with IV antibiotics followed by filgrastim. Mesenteric lymph node open biopsy demonstrated large areas of necrosis and characteristic absence of neutrophils. Thus, KFD and SLE were diagnosed based on SLICC criterion of SLE diagnosis. Treatment with Solumedrol 40 mg IV Q12 resulted in clinical improvement and discharge from hospital. Hydroxychloroquine 200 BID was added with steroid taper as patient continued to improve during outpatient follow ups. Conclusion: It is the first reported case of KFD with mesenteric lymphadenitis as the initial manifestation in a young African American male. This rare presentation masquerades the diagnosis leading to unnecessary procedures and empiric treatments. It warrants further research on the underlying pathophysiology and the need for a standardized diagnostic criterion and treatment guidelines of the disease.