Two cytologic patterns in invasive ductal adenocarcinoma of the pancreas

To clarify 2 cytologic patterns: severe ductal dysplasia (SD)/carcinoma in situ (CIS) and invasive components of invasive ductal adenocarcinoma of the pancreas (IDAP).

Tumor samples from 12 patients with IDAP were examined cytologically and histologically. Cytologic specimens were obtained by fine needle aspiration (ENA) and imprint smears from resected pancreases.

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 microm in short diameter) without prominent anisocytosis. The latter comprised mostly of the tumor cells, were present characteristically as a loose and discohesive population and contained a combination of hyperchromatin, large nuclei (> 15 microm) and abundant cytoplasm (>21 microm). 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 noninvasive intraductal spread.

Two cytologic patterns originating with SD/CIS and invasive components of IDAP could be differentiated.