Double cancers in the common bile duct: molecular genetic findings with an analysis of LOH

We report a 69‐year‐old man with double cancers in the common bile duct. One cancer was located between the superior and middle parts of the bile duct, while the other cancer was in the inferior part of the bile duct. Pylorus‐preserving pancreatoduodenectomy was performed. There was no communication between the two cancers in either the mucosal layer or the subepithelial layer. On pathological examination, the upper cancer was diagnosed as poorly differentiated adenocarcinoma, while the lower one was found to be moderately differentiated adenocarcinoma. We analyzed loss of heterozygosity (LOH), using microsatellite markers on five chromosomal arms, in both the upper and the lower cancers. Both cancers showed common regions of LOH at 5q, 6q, 9p, 17p, and 18q, whereas the upper cancer showed one additional region of LOH at 8p, thus suggesting progression, due to the acquisition of the additional LOH, in the upper cancer. No LOH was observed in the region between the two cancers. The presence of one additional LOH in the upper cancer suggests that the upper cancer was a metastasis of the lower one.