title: Bone marrow findings in severe fever with thrombocytopenia syndrome: prominent haemophagocytosis and its implication in haemophagocytic lymphohistiocytosis.
abstract: OBJECTIVE
  Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease caused by the SFTS virus; primary manifestations are fever, thrombocytopenia, leukopenia and gastrointestinal symptoms. Before an aetiological diagnosis is made, SFTS patients can undergo bone marrow examination due to cytopenias. Although several studies have reported on bone marrow examination in SFTS patients, most do not provide adequate details. Bone marrow findings in SFTS patients were investigated in this study.
  
  
  METHODS
  An observational study was conducted in SFTS patients who were hospitalised between 2013 and 2014 in two university hospitals in South Korea. Patients were included in the study if SFTS was confirmed by real-time PCR for the SFTS virus and a bone marrow examination was conducted. The morphologic findings of the bone marrow samples were reviewed.
  
  
  RESULTS
  Three cases met the study inclusion criteria. One patient died of multiple organ failure. Haemophagocytosis was evident in the bone marrow samples of all three patients. Histiocytic hyperplasia and haemophagocytosis were more pronounced in the fatal case. One patient was diagnosed as having haemophagocytic lymphohistiocytosis.
  
  
  CONCLUSIONS
  Haemophagocytosis in the bone marrow of SFTS patients may be common. In SFTS endemic areas, SFTS should be one of the differential diagnoses of fever of unknown origin with haemophagocytosis in the bone marrow.
authors.affiliation: Department of Laboratory Medicine, Pusan National University School of Medicine, Busan, South Korea.
authors.forename: Namhee
authors.identifier: http://orcid.org/0000-0001-9682-9654
authors.initials: N
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Pusan National University Hospital, Busan, South Korea Biomedical Research Institute, Pusan National University Hospital, Busan, South Korea.
authors.forename: Kye-Hyung
authors.identifier: http://orcid.org/0000-0001-9682-9654
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, Gyeongsangnam-do, South Korea.
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Pusan National University School of Medicine, Busan, South Korea.
authors.forename: Sang-Hyuk
authors.initials: SH
authors.lastname: Park
authors.affiliation: Department of Laboratory Medicine, Pusan National University School of Medicine, Busan, South Korea.
authors.forename: In-Suk
authors.identifier: http://orcid.org/0000-0001-9682-9654
authors.initials: IS
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Pusan National University School of Medicine, Busan, South Korea.
authors.forename: Eun Yup
authors.initials: EY
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Pusan National University School of Medicine, Busan, South Korea Biomedical Research Institute, Pusan National University Hospital, Busan, South Korea.
authors.forename: Jongyoun
authors.initials: J
authors.lastname: Yi
mesh_terms: D000368:Aged; D001853:Bone Marrow / Q000473:pathology* / Q000821:virology; D001856:Bone Marrow Examination; D002044:Bunyaviridae Infections / Q000175:diagnosis* / Q000821:virology; D002675:Child, Preschool; D005260:Female; D005334:Fever; D006801:Humans; D007970:Leukopenia / Q000175:diagnosis* / Q000821:virology; D051359:Lymphohistiocytosis, Hemophagocytic / Q000175:diagnosis* / Q000821:virology; D008297:Male; D008875:Middle Aged; D009102:Multiple Organ Failure; D010587:Phagocytosis; D016856:Phlebovirus / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction; D056910:Republic of Korea; D013921:Thrombocytopenia / Q000175:diagnosis* / Q000821:virology
keywords: BONE MARROW; CLINICAL INFECTIOUS DISEASES; HAEMATOPATHOLOGY; MORPHOLOGY; VIRUS