A case of Hemophagocytic lymphohistiocytosis induced by COVID-19, and review of all cases reported in the literature.

Novel coronavirus infections 2019 (COVID-19) associated hyperinflammatory syndromes are well-defined clinical conditions and have a potential risk for severe infection. Hemophagocytic lymphohistiocytosis (HLH), a rare type of acute progressive hyperinflammatory syndrome, has been reported in a limited number of COVID-19 cases. In this article, we aimed to present a patient with HLH secondary to COVID-19 diagnosed by bone marrow biopsy, and to summarize and review HLH cases associated with COVID-19 in the literature. A 47-year-old male patient presented with complaints of fever, cough, abdominal discomfort, and nausea-vomiting. He had recovered from COVID-19 a month ago and was readmitted to the hospital due to the re-appearance of clinical symptoms after a two-week interval. The patient was diagnosed with HLH secondary to COVID-19 on sixth day of admission and fully recovered with systemic pulse steroid, intravenous immunoglobulin, and plasma exchange therapy. Analysis of literature searches revealed that 22 cases were definitely diagnosed with COVID-19-associated HLH, 16 of them were male. They had been treated with different anti-cytokine drugs, of which nine had died. The increasing number of HLH cases, which have high mortality rates, shows the importance of hyperinflammatory syndromes in COVID-19 patients. Some patients may experience hemophagocytosis in the late period of COVID-19, even while in recovery. Increased awareness and early treatment for HLH triggered by COVID-19 can be a life-saving effort for reducing mortality in severe COVID-19 cases.