title: Primary pure squamous cell carcinoma of the thyroid: report and histogenic consideration of a case involving a BRAF mutation.
abstract: Primary squamous cell carcinoma of the thyroid (SCC-T) is extremely rare. Its clinical presentation is similar to that of anaplastic carcinoma. Metastasis or extension from the head and neck area should be ruled out, as patients with SCC-T have a poorer prognosis than patients who have a thyroid extension from an adjacent tumor. An 87-year-old man presented with a longstanding painless mass in the right thyroid and had experienced 2 months of pain upon swallowing. A right lobectomy was performed with resection of thyroid cartilage, cricoid cartilage, a portion of the first to third tracheal ring and the right neck lymph node. A histological examination revealed pure SCC. The tumor cells showed diffuse immunoreactivity to CK5/6, CK19 and p63. Immunoreactivity to EMA and p53 was focally positive. TTF-1, galectin 3 and thyroglobulin immunoreactivity was restricted to the non-neoplastic thyroid tissue. Both tumor cells and non-neoplastic follicular cells were negative for CD5. The MIB-1 index was 36%. DNA extracted from the tumor identified a BRAF V600E mutation in exon 15 and a BRAF G468A mutation in exon 11, whereas DNA from non-tumorous cells did not contain a mutation. These molecular findings may suggest a direct transformation from papillary carcinoma to SCC-T.
authors.affiliation: Department of Pathology, Konkuk University Medical Center, Gwangjin-gu, Seoul, Korea.
authors.forename: Young Sin
authors.initials: YS
authors.lastname: Ko
authors.forename: Tae Sook
authors.initials: TS
authors.lastname: Hwang
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Han
authors.forename: So Duk
authors.initials: SD
authors.lastname: Lim
authors.forename: Wan Seop
authors.initials: WS
authors.lastname: Kim
authors.forename: Seo Young
authors.initials: SY
authors.lastname: Oh
mesh_terms: D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D002291:Carcinoma, Papillary / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf