Papillary tumors of the thyroid gland (molecular pathology)

Chromosomal comparative genomic hybridization (CGH)

 low prevalence of aberrations
 majority of tumors showing no evidence of chromosomal instability

 gains: chromosomes 1, 5, 7, 11, 15, 17, and 22

 losses: chromosomes 4, 18, and 19

Regional amplification

 TP73 (1p36 amplification)
 SNRPN (15q12 amplification)
 PDGFB (22q13 amplification)

Gene mutations

Oncogenic activation of BRAF (35% to 69%), RAS (10%), or RET (5% to 30%) is common in PTC, and the mutations correlate with tumor subtype, patient age, and clinical behavior.

 BRAF mutations (35% to 69%): BRAF-associated thyroid papillary carcinoma (17199440)
 KRAS mutations (10%)
 RET mutations (5% to 30%)

 BRAF

• Up to 60% of thyroid papillary carcinomas have mutations in the BRAF gene. However, follicular variant of papillary carcinoma has a much lower frequency of mutation.
• Papillary carcinomas of the thyroid with papillary growth and areas of follicular growth have a high frequency of BRAF mutations (BRAF-V600E).
• The BRAF mutational profile is identical in the follicular areas and in the conventional papillary growth areas.

 ALK translocation

• ALK-translocated papillary thyroid carcinoma. (25501013)