We report a FAP-associated CMVPTC tumor with atypically aggressive features harboring a RAS mutation and review the molecular mechanisms associated with this interesting PTC subtype.
The authors performed a retrospective analysis for allelic deletion of the adenomatous polyposis coli (APC) and PTCH gene loci using paraffin embedded medulloblastoma specimens from patients who were admitted to Children's National Medical Center in Washington, DC, between 1982 and 1997.
These findings document that loss of function of apc coexists with gain of function of ret in some papillary thyroid carcinomas, suggesting that ret/ptc1 oncogene activation could be a progression step in the development of FAP-associated thyroid tumors.
Present data suggest that: (1) the incidence of FAP-associated thyroid cancer probably has been underestimated in the past; (2) intensive screening could detect a larger than expected number of thyroid carcinomas; (3) systematic screening is recommended in patients with ocular patches and genetic mutation in exon 15; (4) Hashimoto-like findings do not exclude carcinoma but are a frequent accompanying finding; (5) despite frequent multicentricity and early lymph node involvement, FAP-associated thyroid tumors seem to have an excellent prognosis, in particular those showing ret-PTC activation.