PIK3CA and neoplasm: Conversely, the two OCCC with PIK3CA mutation cases showed coincident sites of PIK3CA mutations in the tumor and endometrial stroma; one of which had H1047R mutation in the endometrial stroma with H1047R mutation in the tumor and the other had E545K mutation in the endometrial stroma with E545K mutation in the tumor (cases c and f).