{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T08:06:00Z","timestamp":1777363560725,"version":"3.51.4"},"reference-count":30,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T00:00:00Z","timestamp":1769644800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cancers"],"abstract":"<jats:p>Background\/Objectives: Mycosis fungoides (MF) and S\u00e9zary syndrome (SS) are cutaneous T-cell lymphomas (CTCLs) with variable clinical outcomes. Peripheral blood (PB) involvement in MF\/SS is an independent predictor of prognosis. Accurate laboratory determination of PB involvement by MF\/SS cells, however, is an ongoing challenge. Both flow cytometry (FC) and morphology-based quantification are limited by the overlap of CTCL cells and reactive T-cells. This study looks at the optimization over time of CTCL blood burden evaluation. Methods: This retrospective study reviews CTCL blood assessment at Northwestern Memorial Hospital from 2012 to 2021. Test ordering and reporting practices for morphology-based S\u00e9zary cell counts and FC were evaluated. For each assay, quantitative and qualitative results were analyzed and compared including percentages and absolute counts of abnormal T-cell populations and pathologist interpretations. Results: A total of 514 patients were evaluated, with increasing numbers of both tests ordered over time. FC quantitative metrics showed a moderate to high correlation with morphology metrics, especially for absolute CD4+\/CD7\u2212 counts (correlation coefficient = 0.901, p-value &lt; 0.001). Qualitative pathologist interpretations had moderate agreement between methods (kappa = 0.58). The recent addition of TRBC1 clonality assessment to our FC assay further optimizes the evaluation for CTCL blood burden. Conclusions: Flow cytometry offers a reliable approach for blood staging in MF\/SS, and morphologic assessment may be redundant. This study provides a foundation for designing a new FC approach with TRBC1. This comprehensive review of the evolution of our laboratory practices may serve as a guide for other institutions with similar clinical needs.<\/jats:p>","DOI":"10.3390\/cancers18030434","type":"journal-article","created":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T10:08:57Z","timestamp":1769681337000},"page":"434","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Laboratory Evaluation of Peripheral Blood Involvement in Mycosis Fungoides and S\u00e9zary Syndrome: Evolution of Flow Cytometry and Morphology Quantification and Interpretation"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5216-3889","authenticated-orcid":false,"given":"Lucy","family":"Fu","sequence":"first","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7765-9637","authenticated-orcid":false,"given":"Payton","family":"Trimark","sequence":"additional","affiliation":[{"name":"Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yijie","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hamza","family":"Tariq","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qing","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yi-Hua","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juehua","family":"Gao","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Barina","family":"Aqil","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joan","family":"Guitart","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6307-5489","authenticated-orcid":false,"given":"Kristy","family":"Wolniak","sequence":"additional","affiliation":[{"name":"Department of Pathology, Feinberg School of Medicine, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,29]]},"reference":[{"key":"ref_1","unstructured":"(2024). 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