Case Presentation: A 19 year old female presented to the student clinic with fevers up to 103 degrees F recurring daily over a period of weeks. She endorsed diffuse body aches and nausea/vomiting. Two years prior, she was diagnosed with Kikuchi disease, a benign self-limited lymphadenitis, following a lymph node biopsy in Bangladesh. Symptoms at that time resolved without intervention. On her current presentation, vital signs were normal with the exception of a fever. Physical exam was unrevealing and did not demonstrate any lymphadenopathy, rash or joint swelling. Initial workup was notable for leukopenia with a white blood cell count of 2.06 k/ul, a mild anemia and a positive tuberculin skin test. She was admitted for further evaluation. Computed Tomography of chest, abdomen and pelvis demonstrated a multifocal pneumonia without evidence of malignancy or lymphadenopathy. She was treated with an empiric course of doxycycline without improvement of her fevers. Sputum cultures were negative for active pulmonary tuberculosis. Additional extensive infectious work-up was negative for HIV, EBV, CMV and parvovirus. Bronchoscopy and bone marrow biopsy were negative for malignancy or infectious etiology. Autoimmune serologies were positive for ANA (1:160) and anti-smooth muscle and ribonucleoprotein antibodies. The patient initially denied any history of rash, however later reported a possible malar rash prior to the onset of fevers. She was subsequently diagnosed with systemic lupus erythematous (SLE) based upon meeting 4 of the American College of Rheumatology (ACR) classification criteria. Plaquenil was started with resolution of her fevers.
Discussion: Fever of unknown origin (FUO) remains a challenging diagnostic problem and often requires inpatient admission. Despite advances in our diagnostic capabilities, more cases of FUO are now being classified as “no diagnosis”. Rheumatologic diseases may not be initially identified, as the diagnosis is often based upon criteria that the patient may not fulfill at the time of the presentation. Approximately 30% of patients with FUO are eventually diagnosed with a rheumatologic disease. SLE remains a rare cause accounting for only 2-3% of cases.
This case additionally illustrates the correlation between Kikuchi disease and SLE. Both diseases have a predilection for young females and share similar clinical presentations, however differ in lymph node histopathology. Several case reports have been published describing the development of SLE in patients previously diagnosed with Kikuchi disease. Unfortunately, there are currently no predictive markers to identify which patients are at risk.
Conclusions: SLE remains a rare cause of FUO with many patients not fulfilling the diagnostic criteria at time of presentation. Given the correlation between Kikuchi disease and SLE, patients should be followed over time as there are currently no predictive markers to identify who will develop SLE.