{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T06:50:10Z","timestamp":1774594210268,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T00:00:00Z","timestamp":1774396800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100010805","name":"Medical Research Council of Southeast Sweden","doi-asserted-by":"crossref","award":["FORSS-1034894"],"award-info":[{"award-number":["FORSS-1034894"]}],"id":[{"id":"10.13039\/100010805","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Lichen planus (LP) is a chronic immune-mediated inflammatory disease of unknown etiology affecting the skin and mucous membranes and is frequently associated with comorbid conditions, although data from Swedish populations remain limited. This retrospective population-based case\u2013control study included all registered citizens in Region J\u00f6nk\u00f6ping, Sweden, between 2013 and 2022, to examine comorbidities, estimate prevalence and incidence, assess diagnostic validity of ICD-10 coding (L43), and evaluate treatment patterns. Incidence and prevalence were calculated, demographic and treatment characteristics were described, and diagnostic validity was assessed through independent medical record review of 70 randomly selected cases to determine positive predictive value (PPV). Associations between LP and predefined comorbidities were analyzed using binomial logistic regression adjusted for age and sex. Among 361,812 individuals, prevalence was 235.5 and incidence 19.6 per 100,000 inhabitants. The PPV of the LP diagnosis was 78.6%, yielding an adjusted prevalence of 184.9 per 100,000 inhabitants. Over one third of prevalent patients received topical therapy, primarily corticosteroids. LP was significantly associated with thyroid, malignant, metabolic, and autoimmune conditions. LP is relatively uncommon, ICD-10 coding shows acceptable validity, and its association with clinically relevant comorbidities highlights the need for comprehensive patient assessment.<\/jats:p>","DOI":"10.3390\/life16040541","type":"journal-article","created":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T10:07:13Z","timestamp":1774433233000},"page":"541","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Comorbidity in Lichen Planus: A Retrospective Population-Based Case\u2013Control Study in Sweden"],"prefix":"10.3390","volume":"16","author":[{"given":"Hilda","family":"Odell","sequence":"first","affiliation":[{"name":"The Faculty of Medicine and Health Sciences, Linkoping University, 58183 Link\u00f6ping, Sweden"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1051-043X","authenticated-orcid":false,"given":"Sandra","family":"Jerkovic Gulin","sequence":"additional","affiliation":[{"name":"Department of Dermatology and Venereology, Ryhov County Hospital, Sjukhusgatan, 55305 J\u00f6nk\u00f6ping, Sweden"},{"name":"Division of Cell Biology, Department of Biomedical and Clinical Sciences, The Faculty of Medicine and Health Sciences, Linkoping University, 58183 Link\u00f6ping, Sweden"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2045-7142","authenticated-orcid":false,"given":"Oliver","family":"Seifert","sequence":"additional","affiliation":[{"name":"Department of Dermatology and Venereology, Ryhov County Hospital, Sjukhusgatan, 55305 J\u00f6nk\u00f6ping, Sweden"},{"name":"Division of Cell Biology, Department of Biomedical and Clinical Sciences, The Faculty of Medicine and Health Sciences, Linkoping University, 58183 Link\u00f6ping, Sweden"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"723","DOI":"10.1056\/NEJMcp1103641","article-title":"Clinical practice. 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