PIK3CA and medullary thyroid gland carcinoma: The prevalence of mutations according to the thyroid tumor type was demonstrated as follows: PTC: BRAF in 40% to 45%, RET/PTC in 6% to 30%, telomerase reverse transcriptase (TERT) promoter in up to 23.5%, RAS in 10% to 20%, and TRK in <5%; FTC: RAS in 40% to 50%, PAX8-PPARγ in 10% to 35%, PIK3CA in <10%, and PTEN in <10%; poorly differentiated carcinoma: RAS in 25% to 30%; CTNNB1 in 10% to 20%, TP53 in 20% to 30%, and BRAF in 10% to 15%; familial forms of medullary carcinoma (MTC): RET in >95%; and sporadic MTC: RET in 40% to 50% [16,18,19].