{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T12:17:59Z","timestamp":1777637879261,"version":"3.51.4"},"reference-count":16,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T00:00:00Z","timestamp":1777420800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:p>This case report describes an unusual clinical course of a patient with papillary thyroid carcinoma (PTC). The patient sequentially developed metastases to the cervical lymph nodes, lungs, pleura, and brain. Following tumor invasion into the latissimus dorsi muscle, a biopsy of this metastatic lesion revealed a BRAF V600E-mutant squamous cell carcinoma (SCC) phenotype indicating a high-grade dedifferentiation from the primary PTC. This metastatic focus also demonstrated upregulation of programmed cell death ligand 1 (PD-L1) expression. Subsequently, the patient exhibited a robust sensitivity to treatment with a programmed cell death protein 1 (PD-1) inhibitor and chemotherapy. This case highlights a highly aggressive evolutionary pattern of PTC and its associated potential for immunotherapy, providing valuable insights for the clinical management of thyroid cancer.<\/jats:p>","DOI":"10.3389\/fimmu.2026.1762050","type":"journal-article","created":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T06:09:14Z","timestamp":1777442954000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Evolution of a BRAF V600E-mutant papillary thyroid carcinoma from latissimus dorsi metastasis and squamous transformation to PD-L1 upregulation and effective immunotherapy"],"prefix":"10.3389","volume":"17","author":[{"given":"Dan","family":"Tian","sequence":"first","affiliation":[{"name":"Department of Oncology, Ordos Central Hospital","place":["Ordos, 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