Invasive ductal adenocarcinoma (IDA) of the pancreas (IDAP) originating from the ductal gland has a poor prognosis worldwide. To improve the prognosis, treatment for noninvasive carcinoma stages is needed. Noninvasive carcinomas are principally intraductal papil-lary-mucinous carcinomas (IPMC) and pancreatic intraepithelial neoplasm 3 (PanIN-3). Small papillary-cohesive clusters, with mainly small regular (about 10 ^m) nuclei, clearly defined cell borders, a mixture of some goblet cells, and a monoclonal aspect are cytologi-cally observed in both IPMC and IPMN, while euchromatin and nuclei malignancy are observed only in IPMC. PanIN-3 cells have small papillary-cohesive and compact clusters, dense and meager cytoplasm without prominent anisocytosis and without cytoplasm >21 ^m at the shortest diameter. The nuclei are individually well enveloped in well preserved cytoplasm separately from each other, and are small regular nuclei mostly highly suspicious for malignancy. IDA cells have loose sheet-solid clusters, poorly preserved cytoplasm, nuclei that tend to adhere to each other, a combination of large nuclei (short diameter >15 ^m) with hyperchromatin, and a monoclonal aspect. To preoperatively differentiate noninvasive IPMC/PanIN-3 from IDAP, these would be clinically very useful.

Copyright © 2007 S. Karger AG, Basel

Precancerous IDAP lesions are mainly PanINs and IPMNs. PanIN has been recently established as a term for intraductal tumors by the WHO [1]. The prognosis of IDAP is still poor, and its occurrence is increasing worldwide. Detection in the early stage is difficult even now, and most cases are detected too late because PanIN-3 (severe dysplasia: SD/carcinoma in situ: CIS) has a rapid cell cycle [2] and invades immediately. However, though rare, several cases have been detected and undergone surgery in PanIN-3 stage [3] with a very good prognosis [3]. Consequently, to improve IDAP prognosis, detection and treatment in PanIN-3 stage is needed. IPMC is often found in the non-invasive carcinoma stage because it is slow growing, and the noninvasive stage extends over a long period of time, showing a distinct clinical entity. We have reported the cytologic features and differences between noninvasive IPMC and IDA [4]. It has been discovered that, in IDAP cases without clinical features of mucin-producing pancreatic tumors, cell clusters resembling noninvasive IPMC cells of the type with dense cytoplasms and scarce goblet cells have been found, and these have been PanIN-3 cells, while the cytologic pattern of PanIN-3 has been distinguishable from that of IDA [5]. Here, we clarify the cytologic features of noninvasive IPMC and PanIN-3, describe the differences from IDA, and consider the differences between noninvasive IPMC and PanIN-3.

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