Case Presentation: A 40-year-old female presented in June of 2023 with emesis and a fever of 38.9 °C. She complained of epigastric pain radiating to the back. The patient reported no recent travel. She worked in a daycare and had a pet dog. She had not hiked or camped recently. She walked her dog at a local park, where she had contact with tall patches of grass. She had no known tick or mosquito bites.Laboratory and imaging findings noted elevated liver enzymes, hyponatremia and retroperitoneal lymphadenopathy.After admission she developed a lower extremity rash that led to initiation of doxycycline and tick-borne serologies being sent. Due to encephalopathy and fever she was started on ceftriaxone and dexamethasone due to concern for meningitis. Lumbar puncture noted slightly increased protein, normal glucose level, monocytosis and a normal opening pressure. Ferritin level was greater than 10,000 ng/mL. IgM antibody for RMSF sent on Day 3 resulted positive at 1.33. Following the initiation of dexamethasone and with continued administration of doxycycline and ceftriaxone, patient’s fevers improved, as did her liver enzymes. Bone marrow aspirate showed a moderate number of histiocytes, of which 75% displayed hemophagocytosis. Dexamethasone was slowly tapered. Patient’s laboratory abnormalities and symptoms had completely resolved on discharge, which occurred on day 15 of hospitalization. Following discharge, IL-2 receptor alpha antibody resulted negative and repeat IgM anti-RMSF antibody level was elevated at 4.20.
Discussion: Hemophagocytic lymphohistiocytosis (HLH), an entity previously reported in the pediatric population, is gaining increased attention in adults. A case series of 775 adults with HLH noted 96% of them presented with fever and two thirds with organomegaly. Skin changes are variable but present in 25% of adults. Neurological findings are common but very variable and can mimic encephalitis.Rocky Mountain Spotted Fever (RMSF) is a potentially deadly tickborne disease endemic to the Midwest and other parts of the United States, caused by the bacteria Rickettsia rickettsii. It causes hyponatremia, vascular injury and a variety of other systemic manifestations including encephalitis, fever and malaise. Between the 3rd and 5th day of infection, a blanching erythematous rash with macules that become petechial over time develops in 88 to 90% of patients.
Conclusions: A 40-year-old female presented with fever and non-specific symptoms. Over the course of her 15-day hospital stay, she developed multi-organ dysfunction and significant laboratory abnormalities consistent with a severe multi-system process. Her symptoms and laboratory findings are not pathognomonic for any specific disease, though she fulfills some objective criteria for the diagnoses of both HLH and RMSF. This case highlights the diagnostic uncertainty that is inherent in the practice of hospital medicine. Prompt empiric treatment and maintaining a wide differential diagnosis allowed this patient to make a complete recovery to her previous level of function.