[Hemophagocytic syndrome secondary to COVID-19: a case report and literature review]

Objective: To improve the awareness of hemophagocytic syndrome(HPS) secondary to COVID-19 (COVID-sHPS). Methods: We reported an adult case of COVID-sHPS, including clinical presentation, laboratory examinations, histopathological findings, treatment strategy, and outcome. We also conducted literature research in PubMed database and Wanfang database using the keywords "COVID-19" and "hemophagocytic syndrome" and subsequently summarized relevant literature. Results: A 49-year-old man was admitted to our hospital after 4 weeks of recurrent fever. Prior to this hospitalization, he had received an empiric combination therapy with antibiotics and antiviral drugs against SARS-CoV-2. His vital signs were within the normal range and no abnormalities were found on physical examination on admission. After admission, throat swab nucleic acid tests were weakly positive for SARS-CoV-2, and negative for influenza and respiratory syncytial virus. Blood nucleic acid tests for cytomegalovirus and EB virus were negative, as was blood mNGS. Laboratory tests showed a series of abnormalities, including leukopenia, thrombocytopenia, low fibrinogen, elevated serum ferritin, elevated transaminase, decreased NK cell activity, and hemophagocytosis in bone marrow. According to the HPS-2004 diagnostic criteria, he was diagnosed with hemophagocytic syndrome, which was high likely to be caused by COVID-19 infection due to the lack of evidence of genetic risk factors and other clear triggers. He was initially treated with dexamethasone at a dose of 10 mg·m^-2·d^-1 and his condition improved rapidly. The literature search identified twenty-three articles on COVID-sHPS, 22 of which were in English. A total of 89 patients had COVID-sHPS and 55 (61.7%) were male. COVID-sHPS could occur at any age, but mainly in adults (86/89, 96%). Fever was reported in the literature with a clear description of the course of the disease. Most HPS occurred during the acute phase of COVID-19, but 3 patients developed HPS during the convalescent phase. Almost all reported cases presented with increased ferritin, elevated transaminases, elevated triglycerides, and cytopenia, mainly anemia and thrombocytopenia. In the retrieved literature, HS-score≥169 was frequently used to diagnose COVID-sHPS, and glucocorticoid in combination with immunoglobulin was the most common treatment strategy. COVID-sHPS had a poor prognosis and a high mortality rate (84.2%, 75/89). Conclusions: The prognosis of COVID-sHPS is poor, so clinicians should raise their awareness of the disease, identify high-risk suspected populations, and arrange reasonable relevant examinations for definite diagnosis and early initial treatment to improve their outcome.