Two Cytologic Patterns in Invasive Ductal Adenocarcinoma of the Pancreas

Objective To clarify 2 cytologic patterns: severe ductal dysplasia (SD)/carcinoma in situ (CIS) and invasive components of invasive ductal adenocarcinoma of the pancreas (IDAP). Study Design Tumor samples from 12 patients with IDAP were examined cytologically and bistologically. Cytologic specimens were obtained by fine necdle aspiration (FNA) and im print smears from resected pancreases. Results In the 12 IDAP cases, roughly 2 cell populations, SD/CIS-type cells and invasive component-type cells, were detected cytologically. The former composed a small portion of the tumor cells, exhibited a small nuclei without anisonucleosis and had a decreased total quantity of chromatin as compared with invasive component-type cells. SD/CIS-type cells were found in small papillary-cohesive and compactly packed clusters and had clearly defined cytoplasmic borders, a nucleus individually enveloped in well-preserved cytoplasm and small amount of cytoplasm ( 15 μm) and abundant cytoplasm (>21 μm). Histologically, these 12 cases exhibited IDAP with SD/CIS. Hence, the invasive component-type cells appeared to originate with ordinary invasive spread of IDAP, and the SD/CIS type cells appeared to originate with non-invasive intraductal spread. Conclusion Two cytologic patterns originating with SD/CIS and invasive components of IDAP could be differentiated.