Differences between solid and duct-ectatic types of pancreatic ductal carcinomas.

Macroscopically, 45 pancreatic ductal carcinomas were classified into two types: solid type (36 tumors) and duct-ectatic type (9 tumors). To disclose the biologic differences between these two types, they were compared by incidence, primary site, histologic types and grades, and biologic behavior. Although 20 solid type carcinomas arose from the branch duct, the duct-ectatic type carcinoma originated in the branch duct in three tumors, in a cyst in one, and in the main duct in one. The major component of the solid type was tubular (glandular) adenocarcinoma with high nuclear atypia and slight mucous secretion. The major component of the duct-ectatic type was papillary adenocarcinoma with low nuclear atypia and abundant mucous secretion. Thirty-four solid type carcinomas showed pancreatic stromal invasion, and 28 showed metastasis. Nine duct-ectatic type carcinomas spread intraductally and had not metastasized. It is concluded that the biologic differences between the two macroscopic type carcinomas are induced by the histologic types and grades.