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This study outlines bottom-up initiated, flexible Swedish Digital Pathology EQA rounds for breast pathology, and presents results from the 2021 and 2023 rounds. Six breast carcinoma cases were selected for each EQA round by the Swedish Breast Pathology Expert Group (KVAST\u00a0Breast). Whole tissue slides stained with HE, IHC, and ISH were anonymized, digitized, and uploaded to the digital EQA platform. Biomarkers were selected based on national registry data analysis and pathologist and clinician feedback. The 2021 round assessed Nottingham grade (NHG), oestrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), while the 2023 round focused on NHG, HER2-low, and global Ki67. Twenty-seven pathology departments participated. From 2021 to 2023, the variability of NHG assessment on digital slides improved from moderate to substantial (kappa 0.50; 95% CI 0.45\u20130.55 to 0.64; 95% CI 0.60\u20130.68), with better agreement for NHG3 than NHG1. Participants showed substantial and excellent agreement in ER (kappa 1) and PR (0.75 (95% CI 0.69\u20130.82). We found similar agreement in distinguishing HER2 IHC 0 (0.78; 95% CI 0.72\u20130.82) and HER2 IHC 3\u2009+\u2009(0.94; 95% CI 0.88\u20131.00) from other HER2 IHC scores. Participants showed substantial agreement in detecting Ki67 high and Ki67 low cases (kappa 0.65; 95% CI 0.60\u20130.71 and 0.69; 95% CI 0.64\u20130.74, respectively). This digital EQA identifies local issues and complements large international EQAs to address challenges in the rapidly changing biomarkers of cancer therapy.<\/jats:p>","DOI":"10.1007\/s00428-025-04059-9","type":"journal-article","created":{"date-parts":[[2025,2,28]],"date-time":"2025-02-28T06:18:59Z","timestamp":1740723539000},"page":"485-493","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A bottom-up initiated digital external quality assessment scheme for the state-of-the-art pathology in Sweden: reduced variability between pathology departments"],"prefix":"10.1007","volume":"489","author":[{"given":"Gunilla","family":"Rask","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Helena","family":"Olofsson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annette","family":"Bauer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Bod\u00e9n","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johannes","family":"van Brakel","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eugenia","family":"Col\u00f3n-Cervantes","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Ehinger","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anik\u00f3","family":"Kov\u00e1cs","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00c5sa","family":"Rundgren-Sellei","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johan","family":"Hartman","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Josefin","family":"\u00c5gren","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eva","family":"Darai-Ramqvist","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Charlotta","family":"Andersson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christina K\u00e5bj\u00f6rn","family":"Gustafsson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0972-4633","authenticated-orcid":false,"given":"Balazs","family":"Acs","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2025,2,28]]},"reference":[{"issue":"7","key":"4059_CR1","doi-asserted-by":"publisher","first-page":"808","DOI":"10.1093\/jnci\/djaa201","volume":"113","author":"TO Nielsen","year":"2021","unstructured":"Nielsen TO, Leung SCY, Rimm DL, Dodson A, Acs B, Badve S et al (2021) Assessment of Ki67 in breast cancer: updated recommendations from the international Ki67 in breast cancer working group. 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JH is a co-founder and shareholder of Stratipath AB. J\u00c5 are employed by Equalis AB. CKG, CA, and E D-R are all members of Equalis Expert group on pathology\/cytology (without remuneration). Other authors have no conflict of interest.","order":2,"name":"Ethics","label":"Conflict of interest","group":{"name":"EthicsHeading","label":"Declarations"}}]}}