{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,30]],"date-time":"2026-10-30T07:49:42Z","timestamp":1793346582049,"version":"4.5.0"},"reference-count":16,"publisher":"AOSIS","issue":"1","license":[{"start":{"date-parts":[[2025,3,25]],"date-time":"2025-03-25T00:00:00Z","timestamp":1742860800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Introduction: Hairy cell leukaemia (HCL) is a rare B-cell lymphoproliferative disorder characterised by medium-sized villous lymphocytes (\u2018hairy cells\u2019) and monocytopenia in the peripheral blood. Automated full blood count (FBC) haematology analysers may spuriously count \u2018hairy cells\u2019 as monocytes, resulting in pseudomonocytosis.\n\nCase presentation: A 72-year-old woman presented with symptomatic anaemia and massive splenomegaly to a regional hospital in North West province, South Africa, in June 2023. An FBC and differential count, performed on a Sysmex XN-series haematology analyser, revealed a monocytosis of 42.82 \u00d7 109\/L. However, a manual differential count, peripheral blood microscopy, and multiparameter flow cytometry confirmed a monocytopenia with numerous \u2018hairy cells\u2019.\n\nManagement and outcome: The patient was referred to a tertiary hospital where bone marrow morphology and a BRAFV600E mutation confirmed a diagnosis of HCL. Unfortunately, she demised shortly after admission.\n\nConclusion: Here, we report a case of HCL where a Sysmex XN-series artifactually counted \u2018hairy cells\u2019 as monocytes, masking the characteristic monocytopenia. With the recent introduction of Sysmex XN-series FBC haematology analysers (Sysmex Corporation, Kobe, Japan) in National Health Laboratory Service laboratories across South Africa, we urge operators to be cognisant of the inherent limitations of FBC analysers in generating blood counts.\n\nWhat this study adds: Even modern automated laboratory analysers with advanced technologies have inherent limitations. This case highlights the importance of a manual differential count and peripheral blood smear review in the era of automation.\n\nKeywords: hairy cell leukaemia; pseudomonocytosis; monocytopenia; haematology full blood count analyser; Sysmex XN-series.<\/jats:p>","DOI":"10.4102\/ajlm.v14i1.2617","type":"journal-article","created":{"date-parts":[[2025,3,25]],"date-time":"2025-03-25T10:47:30Z","timestamp":1742899650000},"update-policy":"https:\/\/doi.org\/10.4102\/crossmark-policy","source":"Crossref","is-referenced-by-count":3,"title":["Pseudomonocytosis on a Sysmex XN haematology analyser masking the monocytopenia of hairy cell leukaemia in a South African woman"],"prefix":"10.4102","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6231-5460","authenticated-orcid":false,"given":"Stephanie J.","family":"Kennedy","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/009xwd568","id-type":"ROR","asserted-by":"publisher"}],"name":"University of the Free State"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6569-4061","authenticated-orcid":false,"given":"Anne-Cecilia","family":"van Marle","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/009xwd568","id-type":"ROR","asserted-by":"publisher"}],"name":"University of the Free State"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2580","published-online":{"date-parts":[[2025,3,25]]},"reference":[{"key":"ref0","doi-asserted-by":"crossref","unstructured":"Cross M, Dearden C. Hairy cell leukaemia. Curr Oncol Rep. 2020;22(5):42. https:\/\/doi.org\/10.1007\/s11912-020-00911-0","DOI":"10.1007\/s11912-020-00911-0"},{"key":"ref1","doi-asserted-by":"crossref","unstructured":"Parry-Jones N, Joshi A, Forconi F, Dearden C; BSH Guidelines Committee. Guideline for diagnosis and management of hairy cell leukaemia (HCL) and hairy cell variant (HCL-V). Br J Haematol. 2020;191(5):730\u2013737. https:\/\/doi.org\/10.1111\/bjh.17055","DOI":"10.1111\/bjh.17055"},{"key":"ref2","doi-asserted-by":"crossref","unstructured":"Tofan L, Piqueras M, Fuster O, et al. Monocytopenia in hairy cell leukemia, a difficult feature to detect using sysmex XN series hematology analyzer. Int J Fam Commun Med. 2022;6(3):94\u201397. https:\/\/doi.org\/10.15406\/ijfcm.2022.06.00271","DOI":"10.15406\/ijfcm.2022.06.00271"},{"key":"ref3","doi-asserted-by":"crossref","unstructured":"Bigorra L, Larriba I, Guti\u00e9rrez-Gallego R. The hairy cell leukaemia oxymoron: Monocytotic monocytopenia. 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Roche Diagnostics (Pty) Ltd; 2022 [cited 2024 Jul 12]. Available from: https:\/\/nhlsqa1.nhls.ac.za\/placement-of-full-blood-count-haematology-analysers-for-nw-fs-limp-mp-gp-kzn-ec-and-wc-nc-regions-including-service-and-maintenance-for-a-period-of-five-5-years-6\/"},{"key":"ref7","doi-asserted-by":"crossref","unstructured":"Ramiah J, Pillay D, Rapiti N. Performance of the automated Sysmex XN-3000 analyser for detecting white blood cell abnormalities in South Africa. Afr J Lab Med. 2023;12(1):2140. https:\/\/doi.org\/10.4102\/ajlm.v12i1.2140","DOI":"10.4102\/ajlm.v12i1.2140"},{"key":"ref8","unstructured":"Joubert J, Weyers R, Raubenheimer JE. Reducing unnecessary blood smear examinations: Can Sysmex blood cell analysers help? Med Technol SA. 2014;28(1):6\u201312."},{"key":"ref9","doi-asserted-by":"crossref","unstructured":"Grever MR, Abdel-Wahab O, Andritsos LA, et al. Consensus guidelines for the diagnosis and management of patients with classic hairy cell leukemia. Blood. 2017;129(5):553\u2013560. https:\/\/doi.org\/10.1182\/blood-2016-01-689422","DOI":"10.1182\/blood-2016-01-689422"},{"key":"ref10","doi-asserted-by":"crossref","unstructured":"Furundarena JR, Sainz M, Uranga A, et al. Comparison of abnormal cell flagging of the hematology analyzers Sysmex XN and Sysmex XE-5000 in oncohematologic patients. Int J Lab Hematol. 2017;39(1):58\u201367. https:\/\/doi.org\/10.1111\/ijlh.12575","DOI":"10.1111\/ijlh.12575"},{"key":"ref11","doi-asserted-by":"crossref","unstructured":"Alaggio R, Amador C, Anagnostopoulos I, et al. The 5th edition of the World Health Organization classification of haematolymphoid tumours: Lymphoid neoplasms. Leukemia. 2022;36(7):1720\u20131748. doi: 10.1038\/s41375-022-01620-2. Erratum in: Leukemia. 2023;37(9):1944\u20131951. https:\/\/doi.org\/10.1038\/s41375-022-01620-2","DOI":"10.1038\/s41375-022-01620-2"},{"key":"ref12","unstructured":"Sysmex Corporation. Chapter 15: p. 466\u2013469. In: Automated Hematology Analyzer XN series Transportation units (XN-9000\/XN-9100). Instructions for use. (ver.22). Kobe: Sysmex Corporation; 2021."},{"key":"ref13","unstructured":"Sysmex Corporation. Chapter 5: p. 66\u201371. In: Automated Hematology Analyzer XN-L series (XN-530\/XN-430\/XN-330). General Information (ver.5). Kobe: Sysmex Corporation; 2020."},{"key":"ref14","unstructured":"Sysmex South Africa Scientific Customer Services. Customer literature list \u2013 White blood cells. 2024(03). 2024 [cited 2024 May 31]. Available from: https:\/\/www.sysmex.co.za\/academy\/library\/publications\/"},{"key":"ref15","doi-asserted-by":"crossref","unstructured":"Schapkaitz E, Raburabu S. Performance evaluation of the new measurement channels on the automated Sysmex XN-9000 hematology analyzer. Clin Biochem. 2018;53:132\u2013138. https:\/\/doi.org\/10.1016\/j.clinbiochem.2018.01.014","DOI":"10.1016\/j.clinbiochem.2018.01.014"}],"container-title":["African Journal of Laboratory Medicine"],"original-title":[],"link":[{"URL":"https:\/\/ajlmonline.org\/index.php\/ajlm\/article\/viewFile\/2617\/3078","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/ajlmonline.org\/index.php\/ajlm\/article\/viewFile\/2617\/3079","content-type":"application\/epub+zip","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/ajlmonline.org\/index.php\/ajlm\/article\/viewFile\/2617\/3080","content-type":"text\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/ajlmonline.org\/index.php\/ajlm\/article\/viewFile\/2617\/3081","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/ajlmonline.org\/index.php\/ajlm\/article\/view\/2617\/3081","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,9,10]],"date-time":"2025-09-10T07:29:17Z","timestamp":1757489357000},"score":1,"resource":{"primary":{"URL":"https:\/\/ajlmonline.org\/index.php\/ajlm\/article\/view\/2617"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,3,25]]},"references-count":16,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2025,1,1]]}},"URL":"https:\/\/doi.org\/10.4102\/ajlm.v14i1.2617","relation":{},"ISSN":["2225-2002","2225-2010"],"issn-type":[{"value":"2225-2002","type":"print"},{"value":"2225-2010","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,3,25]]},"article-number":"a2617"}}