The mucus‐hypersecreting tumor of the pancreas. Development and extension visualized by three‐dimensional computerized mapping

Background. Mucus‐hypersecreting tumor of the pancreas appears as dilated ducts and cystic spaces filled with mucus. To determine where such tumors arise and how they extend, computer‐aided three‐dimensional reconstruction was done of the ductal system. This also was used to visualize the spatial relationships among epithelial hyperplasia, dysplasia, and carcinoma in situ (CIS). Methods. Surgically removed pancreases were studied from 12 patients with mucus‐hypersecreting tumors. The specimens were fixed in buffered formaldehyde solution lo%, embedded in paraffin and semiserially sectioned at 3 pm at an interval of 60 pm. The ductal contours were diffentiated among ducts lined by ordinary epithelia, hyperplastic epithelia, dysplastic cells, or CIS and were inputted into a computer system that integrated a three‐dimensional image of ducts in the display. Results and Conclusions. (1) The tumors arose in the main pancreatic duct or its subbranches, and the cysts corresponded to segments expanded by the superficial growth of tumor cells; (2) areas of CIS arose in zones of preceding dysplasia, suggesting a dysplasia‐carcinoma sequence; and (3) dysplastic or cancerous cells often extended intraductally over the dilated segments of ducts.