Hemophagocytic Lymphohistiocytosis in a Patient With Post-acute COVID-19 Infection.

Hemophagocytic lymphohistiocytosis (HLH) is characterized by immune dysregulation with extensive inflammation and tissue destruction due to abnormal immune activation. Post-COVID-19 patients who have recovered with negative serologic tests may also present with secondary HLH, an unusual finding that our case demonstrates. A 73-year-old male with a notable past medical history of fall COVID-19 infection approximately 11 months prior presented initially to emergency services with a chief complaint of high fevers, lethargy, and progressive changes in mentation gradually progressive over the last 5 months' duration. This presentation was concerning for HLH in view of the patient's high H score and clinical suspicion for HLH, and he was initiated on dexamethasone 20 mg daily. intravenous immune globulin (IVIG) protocol was also trialed, despite which the patient continued to deteriorate before expiring during the course of the hospitalization. sHLH following COVID-19 infection remains a poorly understood phenomenon. The severity of the COVID-19 infection does not appear to be related to one's predisposition to develop sHLH. The mortality of HLH remains high even with appropriate therapy.