In conclusion, we found the occurrence of RHOA mutations, which are reminiscent of the diffuse subtype of gastric cancers or appendiceal GCAs, in 13% of SB-PCC cases, while mutations commonly involved in colorectal and small bowel adenocarcinomas (such as those involving KRAS, PIK3CA) are rarely, if ever, seen in SB-PCCs. Here, PIK3CA is linked to gastric cancer.