{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T16:12:05Z","timestamp":1791994325725,"version":"4.4.0"},"reference-count":32,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,11,27]],"date-time":"2025-11-27T00:00:00Z","timestamp":1764201600000},"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: Actinic keratosis (AK) is a precancerous lesion that may progress into cutaneous cancer. However, the progression potential of individual lesions remains unpredictable. The histological basal proliferation pattern of AKs may serve as a risk marker for progression, yet it cannot be assessed clinically. The objective was to evaluate whether Olsen grading (hyperkeratosis of AKs) and pain as clinical markers correlate with the histological basal proliferation (PRO) and different histological aspects. Methods: In this retrospective two-center study, 380 clinically diagnosed AKs were graded according to the clinical Olsen classification (I\u2013III) and assessed for pain upon palpation. Histologically, they were classified based on their basal- (PRO I\u2013III) and upward-directed (AK I\u2013III) growth patterns, and additional histopathological features, such as acantholysis, were documented. Results: Olsen grading showed weak correlation with the PRO classification (Spearman\u2019s rho = 0.136, p = 0.008), with exact agreement of 36.3% (\u03ba = 0.07). Pain was significantly associated with higher PRO grades (p = 0.005) and acantholysis (p = 0.023) but not with Olsen grades or upward-directed growth (AK I\u2013III). Conclusions: Olsen grading does not allow reliable prediction of basal proliferation patterns in AKs. Its use as a clinical severity scale may suggest progression relevance; however, no substantiated association with histological indicators of transformation could be demonstrated in this study. The presence of pain, however, correlated with high PRO grades and the presence of acantholysis.<\/jats:p>","DOI":"10.3390\/cancers17233794","type":"journal-article","created":{"date-parts":[[2025,11,27]],"date-time":"2025-11-27T11:50:13Z","timestamp":1764244213000},"page":"3794","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Clinical Olsen Grading Does Not Reflect Basal Growth in Actinic Keratoses: Two-Center Retrospective Analysis"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9627-2179","authenticated-orcid":false,"given":"Lutz","family":"Schmitz","sequence":"first","affiliation":[{"name":"CentroDerm, Heinz-Fangman-Stra\u00dfe 57, 42287 Wuppertal, Germany"},{"name":"Department of Dermatology, Venereology and Allergology, Ruhr-University, 44780 Bochum, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Conrad","family":"Falkenberg","sequence":"additional","affiliation":[{"name":"CentroDerm, Heinz-Fangman-Stra\u00dfe 57, 42287 Wuppertal, Germany"},{"name":"Faculty of Health, University of Witten-Herdecke, Alfred-Herrhausen-Stra\u00dfe 50, 58448 Witten, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5479-5222","authenticated-orcid":false,"given":"Julius","family":"Balkenhol","sequence":"additional","affiliation":[{"name":"CentroDerm, Heinz-Fangman-Stra\u00dfe 57, 42287 Wuppertal, Germany"},{"name":"Faculty of Health, University of Witten-Herdecke, Alfred-Herrhausen-Stra\u00dfe 50, 58448 Witten, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-0571-8413","authenticated-orcid":false,"given":"Paul","family":"Melzer","sequence":"additional","affiliation":[{"name":"CentroDerm, Heinz-Fangman-Stra\u00dfe 57, 42287 Wuppertal, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9745-2369","authenticated-orcid":false,"given":"Wolfgang G.","family":"Philipp-Dormston","sequence":"additional","affiliation":[{"name":"Faculty of Health, University of Witten-Herdecke, Alfred-Herrhausen-Stra\u00dfe 50, 58448 Witten, Germany"},{"name":"Hautzentrum K\u00f6ln, 50996 Cologne, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7804-5311","authenticated-orcid":false,"given":"Thomas","family":"Dirschka","sequence":"additional","affiliation":[{"name":"CentroDerm, Heinz-Fangman-Stra\u00dfe 57, 42287 Wuppertal, Germany"},{"name":"Faculty of Health, University of Witten-Herdecke, Alfred-Herrhausen-Stra\u00dfe 50, 58448 Witten, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1024","DOI":"10.1111\/jdv.19897","article-title":"European Consensus-based Interdisciplinary Guideline for Diagnosis, Treatment and Prevention of Actinic Keratoses, Epithelial UV-induced Dysplasia and Field Cancerization on Behalf of European Association of Dermato-Oncology, European Dermatology Forum, European Academy of Dermatology and Venereology and Union of Medical Specialists (Union Europ\u00e9enne Des M\u00e9decins Sp\u00e9cialistes)","volume":"38","author":"Kandolf","year":"2024","journal-title":"Acad. 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