Secondary tumors of the pancreas: Clinicopathological study of 103 autopsy cases of Japanese patients

To investigate the clinicopathological features of patients with secondary tumors of the pancreas, we reviewed autopsy records and pathological features of 103 cases with pancreatic secondary tumors from 690 cases of malignant tumors (excluding cases of primary pancreatic cancer) over a 10-year period. There were 67 men and 36 women in the study, ranging in age from 2 to 94 years (mean: 61 years). The incidence of pancreatic secondary tumors was 15% in the autopsy cases of malignant tumors, and the majority of the secondary tumors were carcinomas. The stomach was the most common primary tumor site (20%), followed by the lung (18%) and extrahepatic bile duct (13%). Because the total number of each primary carcinoma differed, we paid specific attention to the incidence of pancreatic metastasis in each primary carcinoma. We found that carcinoma of the papilla of Vater showed the highest rate of incidence (75%) of pancreatic metastasis in each type of primary carcinoma. Approximately half of the metastatic lesions were solitary, but the metastatic lesions in the pancreas could not be identified macroscopically in 34 cases (33%). Histologically, the most common carcinoma was adenocarcinoma, followed by large cell carcinoma, small cell carcinoma and neuroendocrine carcinoma. The most common non-epithelial tumor was leukemia, followed by malignant lymphoma. Undifferentiated carcinoma and neuroendocrine carcinoma were often found in cases of extrahepatic bile duct or urinary bladder carcinoma with pancreatic metastasis. As for the microscopic infiltration patterns of tumor cells, 73% of cases showed an interlobular and intralobular infiltration. Fat necrosis was most frequently seen as an associated pathological finding (19%). Our study indicates that secondary tumors of the pancreas can be found in approximately one out of six to seven autopsy cases of malignant tumors, and in Japan, the most common of these is adenocarcinoma of the stomach.