Published online Jul 28, 2021. doi: 10.3748/wjg.v27.i28.4738
Peer-review started: May 7, 2021
First decision: June 6, 2021
Revised: June 15, 2021
Accepted: July 9, 2021
Article in press: July 9, 2021
Published online: July 28, 2021
Processing time: 80 Days and 4.2 Hours
Adenocarcinoma originating from heterotopic pancreas tissue is a rare disease. Furthermore, to our knowledge, no HER2-positive cases in the duodenum have been reported in the scientific literature nor has the efficacy of trastuzumab treatment for the disease been reported.
A 65-year-old woman whose clinical diagnosis was unresectable advanced duodenal cancer with HER2 overexpression responded well to trastuzumab chemotherapy. The main tumor in the duodenum reduced drastically. The patient underwent pancreaticoduodenectomy and lymph node dissection. A small number of cancer cells remained in the submucosal layer of the duodenum and pancreas head. After histological and immunohistochemical examination, the patient was diagnosed with duodenal adenocarcinoma originating from heterotopic pancreas tissue.
Trastuzumab treatment is effective in HER2-positive adenocarcinoma originating from heterotopic pancreas tissue in the duodenum.
Core Tip: Adenocarcinoma that develops from heterotopic pancreas tissue in the duodenum is a very rare disease. Therefore, standard chemotherapy regimens to treat these patients have not been established. A 65-year-old woman presented with unresectable duodenal cancer with HER2 overexpression. Because the patient responded well to trastuzumab chemotherapy, pancreatoduodenectomy was performed. Histology and immunohistochemistry assessments revealed that the cancer developed from heterotopic pancreas tissue in the duodenum. The findings of this case suggest that HER2 status should be examined in duodenal adenocarcinoma to determine the indication for targeted therapy. Trastuzumab chemotherapy is effective for heterotopic pancreatic adenocarcinoma but not orthotopic pancreatic cancer.