{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T11:40:59Z","timestamp":1789472459993,"version":"build-2803163510"},"reference-count":32,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2024,10,26]],"date-time":"2024-10-26T00:00:00Z","timestamp":1729900800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2024,10,26]],"date-time":"2024-10-26T00:00:00Z","timestamp":1729900800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Vet Res"],"abstract":"<jats:title>Abstract<\/jats:title><jats:sec>\n                <jats:title>Background<\/jats:title>\n                <jats:p>Chronic lymphoid leukemia (CLL) is a hematological disorder characterized by the clonal expansion of small mature lymphocytes that accumulate in the blood and bone marrow. CLL can arise from B-, T-, or natural killer cell clones. The cytological evaluation of blood smears is often the simplest and least invasive method for diagnosing lymphoid leukemia. Immunophenotyping is used to further subclassify the type of lymphoid leukemia.<\/jats:p>\n              <\/jats:sec><jats:sec>\n                <jats:title>Case presentation<\/jats:title>\n                <jats:p>A 15-year-old, 4.4-kg spayed female Shih Tzu was presented to the veterinary medical teaching hospital of Kangwon National University. Despite having a normal appetite and activity level, cervical and inguinal lymph node enlargement was noted on physical examination. Complete blood count revealed severe leukocytosis, severe lymphocytosis, and monocytosis. Splenomegaly, hepatomegaly, and lymph node enlargement were detected on radiographic and ultrasonographic examination. Immunophenotyping was performed using peripheral blood mononuclear cells (PBMCs). The majority of lymphocytes exhibited the following profiles: CD3<jats:sup>\u2212<\/jats:sup>CD79a<jats:sup>\u2212<\/jats:sup> (97.5%), CD4<jats:sup>\u2212<\/jats:sup>CD8<jats:sup>\u2212<\/jats:sup> (98.6%), CD21<jats:sup>\u2212<\/jats:sup>CD79a<jats:sup>\u2212<\/jats:sup> (98.4%), CD34<jats:sup>\u2212<\/jats:sup> (0.1%), CD45<jats:sup>+<\/jats:sup> (99.6%), major histocompatibility complex class II<jats:sup>+<\/jats:sup> (99.5%), and CD14<jats:sup>\u2212<\/jats:sup> (0.5%). Based on the immunophenotyping results, possible differentials considered included the following: the majority of lymphocytes may be natural killer (NK) cell clones, plasma cell clones, or show aberrant expression or loss of CD21 marker due to the neoplastic nature of the cells. Further flow cytometry was performed using antibodies against CD3, CD5, CD94, and granzyme B. The combined results indicated that the predominant lymphocyte subset in the PBMCs was CD3<jats:sup>\u2212<\/jats:sup>CD5<jats:sup>\u2212<\/jats:sup>CD21<jats:sup>\u2212<\/jats:sup>CD94<jats:sup>\u2212<\/jats:sup>granzyme B<jats:sup>\u2212<\/jats:sup>. To confirm monoclonality and exclude the aberrant loss of CD markers, a polymerase chain reaction for antigen receptor rearrangement (PARR) assay was conducted. The PARR assay, using DNA from blood and lymph node samples, showed B-cell monoclonality. Immunocytochemistry using PBMCs showed that the plasma cell marker Multiple Myeloma Oncogene 1 (MUM1) was not expressed. Therefore, the diagnosis was confirmed to be B-cell CLL.<\/jats:p>\n              <\/jats:sec><jats:sec>\n                <jats:title>Conclusion<\/jats:title>\n                <jats:p>Immunophenotyping can help subclassify the type of lymphoid leukemia; however, as tumor cells can show aberrant expression or loss of the CD21 marker, combining immunophenotyping with the PARR assay could yield a more accurate diagnosis.<\/jats:p>\n              <\/jats:sec>","DOI":"10.1186\/s12917-024-04335-x","type":"journal-article","created":{"date-parts":[[2024,10,26]],"date-time":"2024-10-26T06:02:07Z","timestamp":1729922527000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Diagnosis of canine B-cell chronic lymphoid leukemia with a CD21 negative phenotype using the LT21 clone CD21 antibody in flow cytometry: a case report"],"prefix":"10.1186","volume":"20","author":[{"given":"Eun Wha","family":"Choi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yunho","family":"Jeong","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin-Ok","family":"Ahn","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2024,10,26]]},"reference":[{"key":"4335_CR1","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1111\/j.1939-1676.2010.0640.x","volume":"25","author":"S Comazzi","year":"2011","unstructured":"Comazzi S, Gelain ME, Martini V, Riondato F, Miniscalco B, Marconato L, Stefanello D, Mortarino M. 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All data collected in this study were generated as part of the patient\u2019s diagnostic workup. Informed consent was obtained from the dog owners for the use of their pet\u2019s medical data for educational and research purposes. This case report was reviewed and approved by the Institutional Animal Care and Use Committee of the Kangwon National University (KW-180921-2).","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethics approval and consent to participate"}},{"value":"This study was a case report of a canine patient, and the identification information, such as patient name, was excluded. All images used in this study were generated by the authors during the diagnostic process. Informed consent was obtained from the dog owner for the use of their pet\u2019s medical data for research purposes (case study).","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Consent for publication"}},{"value":"The authors declare no competing interests.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"490"}}