FOLLICULAR THYROID CARCINOMA (FTC)
FTC is a proven component cancer in PTEN-related CS and Werner syndrome. In germline PTEN mutation-positive CS, FTC is the major component of thyroid cancer (Harach et al. 1999; Ni et al. 2008; Bennett et al. 2010). However, rarely, PTC and the follicular variant of PTC are also observed (Marsh et al. 1998). In Werner syndrome, thyroid carcinoma, mainly FTC, is more commonly observed in Japanese patients than those from elsewhere.
The molecular etiology of sporadic FTC remains unknown. A publication reporting a high frequency (50%) of somatic PAX8/PPARG translocations in FTC initially suggested that this was the initiating event (Kroll et al. 2000).
Subsequently, the frequency of this PAX8/PPARG translocation, which inactivates PPARG by a dominant negative mechanism, was found to be much less (10%) in sporadic FTC (Aldred et al. 2003). Instead, loss of function by a haploinsufficient mechanism seems to occur more frequently and plays some role in FTC development (Aldred et al. 2003). Microarray expression strategies have been used to attempt to elucidate the molecular pathogenesis of sporadic FTC (Aldred et al. 2003).