title: Columnar cell variant of papillary thyroid carcinoma: a study of 10 cases with emphasis on CDX2 expression.
abstract: BACKGROUND
  Columnar cell variant is a recognized rare variant of papillary thyroid carcinoma (PTC) that has an uncertain clinical course. This variant has two subvariants, and one is regarded as a more aggressive form in comparison to the more common classical and follicular variants. These tumors have morphological resemblance with endometrial or colonic adenocarcinoma. CDX2, a transcription factor of the caudal homeobox family, plays a key role in intestinal development and differentiation, and it is widely used as a marker to detect adenocarcinomas of intestinal and colonic origin. CDX2 has been rarely reported in PTC.
  
  
  METHODS
  We studied 10 cases of columnar cell variant of PTC (CCV-PTC). The histological, architectural, and cytological features fulfilled the diagnostic criteria of the CCV-PTC, as defined by the current World Health Organization classification. Ten patients (six men and four women) ranging in age from 32 to 90 years (mean, 58.3 years) presented with tumors classified as indolent (four cases) or aggressive (six cases); three harbored a BRAF(V600E) mutation. All cases were β-catenin negative. The Ki-67 proliferative index was up to 50%. All cases were thyroid transcription factor-1-positive. Using paraffin-embedded blocks, immunohistochemistry for CDX2 was performed to evaluate the reactivity of this antibody to this variant of PTC.
  
  
  RESULTS
  Nuclear positivity for CDX2 was detected in one out of the 10 cases studied (10%); the other nine cases did not express CDX2.
  
  
  CONCLUSIONS
  Only one of our cases showed nuclear positivity for CDX2. Therefore, our study failed to confirm it as a marker for CCV-PTC. The absence of CDX2 in the majority of the cases does not support the theory of CDX2 playing a role in the intestinal phenotype of these tumors.
authors.affiliation: Department of Pathology, University of Miami, Miami, Florida, USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Sujoy
authors.forename: André
authors.initials: A
authors.lastname: Pinto
authors.forename: Vânia
authors.initials: V
authors.lastname: Nosé
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D000071616:CDX2 Transcription Factor; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000628:therapy; D002291:Carcinoma, Papillary; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D005260:Female; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D000077273:Thyroid Cancer, Papillary; D013961:Thyroid Gland / Q000378:metabolism* / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000628:therapy; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D015415:Biomarkers; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; D018398:Homeodomain Proteins; D009363:Neoplasm Proteins