Hemophagocytic lymphohistiocytosis, a new cause of death during 'post-acute COVID-19 syndrome?' A case report.

'Post-acute coronavirus disease 2019 (COVID-19) syndrome' is a new term that was coined to describe a constellation of persistent symptoms and new complications following recovery from COVID-19 initial illness. Identifying post-COVID-19 complications is crucial for early diagnosis and subsequent initiation of therapies to ensure more favorable outcomes. Severe COVID-19-related hemophagocytic lymphohistiocytosis (HLH) has been previously described during the acute phase of the infection. It is characterized by hyperinflammation, multi-organ involvement, and hemophagocytosis. We report the case of a 69-year-old woman who presented, two weeks after recovery from COVID-19, with hyperosmolar state and high inflammatory markers. Bone marrow aspirate, flow cytometry, extensive viral panel and total body scan were performed. Review of bone marrow aspirate smear showed hemophagocytosis. Flow cytometry, viral panel, and total body scan were normal. The diagnosis of post COVID-19-related HLH was made. Unfortunately, the patient died despite adequate treatment. To our knowledge, this is the first case establishing a high probability of COVID-19-related HLH given its occurrence two weeks following a documented biological and clinical recovery. Awareness and early recognition of HLH features following COVID-19 recovery should prompt timely initiation of therapy.