RT Journal Article SR Electronic T1 Secondary haemophagocytic lymphohistiocytosis in COVID-19: correlation of the autopsy findings of bone marrow haemophagocytosis with HScore JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 383 OP 389 DO 10.1136/jclinpath-2020-207337 VO 75 IS 6 A1 Núñez-Torrón, Claudia A1 Ferrer-Gómez, Ana A1 Moreno Moreno, Esther A1 Pérez-Mies, Belen A1 Villarrubia, Jesús A1 Chamorro, Sandra A1 López-Jiménez, Javier A1 Palacios, J A1 Piris-Villaespesa, Miguel A1 García-Cosío, Mónica YR 2022 UL http://jcp.bmj.com/content/75/6/383.abstract AB Background Secondary haemophagocytic lymphohistiocytosis (sHLH) is characterised by a hyper activation of immune system that leads to multiorgan failure. It is suggested that excessive immune response in patients with COVID-19 could mimic this syndrome. Some COVID-19 autopsy studies have revealed the presence of haemophagocytosis images in bone marrow, raising the possibility, along with HScore parameters, of sHLH.Aim Our objective is to ascertain the existence of sHLH in some patients with severe COVID-19.Methods We report the autopsy histological findings of 16 patients with COVID-19, focusing on the presence of haemophagocytosis in bone marrow, obtained from rib squeeze and integrating these findings with HScore parameters. CD68 immunohistochemical stains were used to highlight histiocytes and haemophagocytic cells. Clinical evolution and laboratory parameters of patients were collected from electronic clinical records.Results Eleven patients (68.7%) displayed moderate histiocytic hyperplasia with haemophagocytosis (HHH) in bone marrow, three patients (18.7%) displayed severe HHH and the remainder were mild. All HScore parameters were collected in 10 patients (62.5%). Among the patients in which all parameters were evaluable, eight patients (80%) had an HScore >169. sHLH was not clinically suspected in any case.Conclusions Our results support the recommendation of some authors to use the HScore in patients with severe COVID-19 in order to identify those who could benefit from immunosuppressive therapies. The presence of haemophagocytosis in bone marrow tissue, despite not being a specific finding, has proved to be a very useful tool in our study to identify these patients.All data relevant to the study are included in the article.