P2.235: Fever of Unknown Origin: Disseminated Coccidioidomycosis in a 5-year-old female

Introduction: The risk of dissemination of coccidioidomycosis, or Valley Fever, can be substantially reduced by early diagnosis and intervention. Arizona and California account for 95% of reported cases. Fever of unknown origin (FUO) should be considered in pediatric patients with a temperature >38.3°C (101°F) for ≥8 consecutive days with no identified source following initial outpatient or hospital evaluation. This can also include a history of three outpatient visits or three consecutive inpatient days without an identified cause.

Case Description: A 5-year-old previously healthy female, born late preterm and up-to-date with vaccines, presented to the pediatric emergency department (PED) with daily fevers >101°F for 19 consecutive days. She had two prior ED visits without symptom resolution despite antibiotics. Fevers were associated with generalized malaise, cervical spine and rib pain, decreased appetite, and weight loss. She was pale and ill-appearing, but with intact mental status. Physical exam showed pale conjunctiva, limited neck range of motion, no murmur or respiratory distress, a soft abdomen, and a nonfocal neurological exam. Serologies revealed anemia, a normal cell differential, no electrolyte derangement, and elevated ESR (96) and CRP (78.68). A CT head without contrast showed an abnormality in the left parietal bone, with concern for osteomyelitis. Urine, cerebrospinal fluid, and respiratory panels were normal. Pediatric infectious disease consulted and agreed on admission for further workup. Additional imaging revealed lytic bone lesions throughout her spine, ribs, long bones, facial bones, sternum, vertebrae, and pelvis, raising concern for Langerhans cell histiocytosis. A femur biopsy revealed histiocytes, and biopsy cultures grew Coccidioides posadasii, leading to a diagnosis of disseminated coccidioidomycosis. A PICC was placed, and daily amphotericin B infusions were initiated. On Day 26 of treatment, the patient returned to the hospital and was admitted to the PICU after routine laboratory evaluation revealed severe hypokalemia. Other labs were unremarkable and less concerning for renal injury, so the patient was then transitioned to fluconazole. Outpatient follow-up continued to trend Coccidioides antibody CF, which showed improvement from 1:64 to 1:8 while on high-dose fluconazole.

Discussion: Fever lasting less than 8 days is common in pediatric patients, but fevers ≥8 days require more thorough evaluation. While cough or URI are common precursors to a Coccidioides diagnosis, this case presents fever and bone pain as the only symptoms. Coccidioides is not typically tested in Southern Nevada due to its low prevalence.

Conclusion: When evaluating FUO in the emergency department, expanding the differential and conducting appropriate tests are essential for timely diagnosis and management of rare diseases. Early identification of disseminated coccidioidomycosis is crucial for effective treatment and improved prognosis.