Undifferentiated carcinoma of the ampulla of Vater.

Undifferentiated carcinoma of the ampulla of Vater is a rare disease with unclear and clinical characteristics and prognosis. Here, we report the case of a 61-year-old man with undifferentiated carcinoma of the ampulla of Vater. He presented to our hospital with an increase in hepatobiliary system enzymes that was detected during a health check-up. Imaging and endoscopy demonstrated a tumor with ulcer in the ampulla of Vater, which was diagnosed as a carcinoma by biopsy. No distant metastasis was observed. Subtotal stomach-preserving pancreaticoduodenectomy was performed. Undifferentiated carcinoma was confirmed based on the presence of small round atypical cells with the formation of a solid alveolar lesion on histopathological examination and immunohistochemical staining that was positive for CAM 5.2 but negative for chromogranin A and synaptophysin. The tumor infiltrated the duodenum, but not the pancreas; no lymph node metastasis was observed. However, liver metastases were detected 2 months postoperatively. Chemotherapy was performed, and the tumor size temporality decreased; however, it grew in size again, and the patients subsequently died of the primary disease 15 months postoperatively. Undifferentiated carcinoma of the ampulla of Vater is a very rare histological type. More number of cases is necessary to clarify optimal treatment.