PIK3CA and carcinoma of the ampulla of vater: In comparison to other BTCs, ampullary carcinomas have a higher rate of PIK3CA (13%) and KRAS (54%) mutations, and these mutations have been reported to co-exist.31 Whether the response of this patient to everolimus is a consequence of their PIK3CA mutation status, or reflective of other biological features unique to ampullary carcinoma requires additional investigation.