P2.L231: Isles of White in a Sea of Red: A Case Report on Dengue Fever Complicated by Hemophagocytic Lymphohistiocytosis

Introduction: Dengue, an infection caused by dengue virus, is transmitted by the Aedes aegypti mosquito in subtropical and tropical climates. Endemic locations are often popular tourist sites, and thus, dengue can present globally as a common travel-related illness. Most individuals are asymptomatic, or develop dengue fever characterized by high fevers, vomiting, myalgias and/or rash. Hemophagocytic lymphohistiocytosis (HLH), an uncommon hyperinflammatory syndrome with overlapping clinical features, has been increasingly reported as a complication of dengue and is frequently fatal. We describe a case of severe dengue fever with HLH in an adolescent traveler who was promptly diagnosed and made a full recovery.

Case Description: A 17-year-old male presented multiple times to the emergency department in Minnesota, with a 7-day history of fever and rash following travel to Mexico three weeks prior. He was admitted for fluid resuscitation due to persistent vomiting in the setting of headache and myalgia. He was found to have a positive Tourniquet test and a confluent maculopapular rash with areas of sparing. Severe dengue was confirmed by positive dengue virus polymerase chain reaction and elevated transaminase levels. Despite prompt, adequate fluid management, his clinical course was complicated by persistent fever and malaise. Additional workup was notable for splenomegaly, thrombocytopenia, anemia and hyperferritinemia. He was subsequently diagnosed with HLH based off an H score predictive probability of >90%. Given his clinical stability and clear triggering condition he was managed conservatively without immunosuppression and made a full recovery.

Discussion: Most cases of dengue are asymptomatic and laboratory testing is often not obtained. Subsequently, dengue is often self-managed or misdiagnosed as another febrile illness. Therefore, the true incidence of dengue fever is underreported. HLH can have many etiologies. It presents with high fevers, cytopenias, hepatosplenomegaly and hyperferritinemia. Due to the similar clinical features, and the significant potential for morbidity and mortality, this complication should be a differential for patients with dengue fever with an atypical clinical course – particularly prolonged fevers. Although reports of HLH secondary to dengue have been well-described, it has not been described in a pediatric patient in a nonendemic area, managed conservatively. Once again, the true incidence of this phenomenon is likely higher as HLH testing is not routinely accessible and/or performed.

Conclusion: This case highlights a rare presentation of dengue fever induced HLH in a nonendemic area. Pediatricians should be cognizant of dengue when considering differential diagnoses for fever in a returning traveller, regardless of practice location. Moreover, providers should become familiar with the pathognomonic features of dengue fever, i.e. the “isles of white in a sea of red” maculopapular rash, to prevent delay in diagnosis and ensure timely escalation of care. Considerations for work-up and management should include common and uncommon complications (dengue hemorrhagic fever, dengue shock syndrome, HLH).