{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T10:03:10Z","timestamp":1789639390298,"version":"4.0.0"},"reference-count":35,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T00:00:00Z","timestamp":1789516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Dermatopathology"],"abstract":"<jats:p>Basal cell carcinosarcomas (BCCSs) are rare, aggressive biphasic epithelial\u2013mesenchymal neoplasms typically occurring in elderly patients. Their nonspecific clinical presentation may mimic inflammatory disorders, necessitating histopathological examination. We characterize a novel cutaneous BCCS with prominent trichoblastic differentiation, clinically mimicking ulcerative pyoderma gangrenosum. Although morphologically resembling trichoblastic carcinosarcoma (TBCS), the tumor retained a BCC-associated genetic signature, supporting a basal cell rather than a primary trichoblastic lineage. We therefore propose the provisional designation \u201cbasal cell carcinosarcoma with divergent trichoblastic differentiation (BCCS-DTB)\u201d, suggesting acquired follicular lineage plasticity within a Hedgehog-driven, UV-mutagenized BCC clone. Shared molecular alterations across epithelial and sarcomatous components support monoclonality and an inside-out epithelial\u2013mesenchymal transition (EMT) model, with progressive acquisition of trichoblastic and sarcomatous features. The patient\u2019s young age, unusual tumor location, and development during the COVID-19 pandemic raise the hypothesis of additional environmental influences. Detection of associated spike protein and Snail expression is hypothesis-generating given their reported association with EMT. Further cases are required to validate the molecular profile for diagnostic and therapeutic relevance involving Hedgehog, FGFR2, and mTOR signaling.<\/jats:p>","DOI":"10.3390\/dermatopathology13030045","type":"journal-article","created":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T08:03:17Z","timestamp":1789632197000},"page":"45","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Skin Basal Cell Carcinosarcoma in a Trichoblastic Guise\u2014Molecular Characterization of a Novel Entity Mimicking a Pyoderma Gangrenosum"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-2454-2354","authenticated-orcid":false,"given":"Paul","family":"Georg","sequence":"first","affiliation":[{"name":"Department of Dermatology, Inselspital, University Hospital Bern, Anna-Seiler-Allee 33, 3010 Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roland","family":"Blum","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Inselspital, University Hospital Bern, Anna-Seiler-Allee 33, 3010 Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert","family":"Hunger","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Inselspital, University Hospital Bern, Anna-Seiler-Allee 33, 3010 Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bastian","family":"Dislich","sequence":"additional","affiliation":[{"name":"Institute of Tissue Medicine and Pathology, University of Bern, Murtenstrasse 31, 3008 Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9586-0799","authenticated-orcid":false,"given":"Ronald","family":"Wolf","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Inselspital, University Hospital Bern, Anna-Seiler-Allee 33, 3010 Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,16]]},"reference":[{"key":"ref_1","unstructured":"Virchow, R. 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