Cytologic Features of Noninvasive IPMC and PanIN3 and Differences from IDA

Cytologic Features of Noninvasive IPMC

IPMC is commonly clinically detected as a mucin-producing tumor of the pancreas. They were first reported by Ohhashi et al. [6]. This type of tumor has characteristic features, such as an enlarged papilla of Vater with a patulous orifice that secretes mucin and a dilated main pancreatic duct, and has, unlike ordinary pancreatic cancer, a favorable prognosis [6]. The entity was established by the WHO in 1996 as a noninvasive IPMN exocrine tumor of the pancreas [7]. Not only carcinomatous, but also adenomatous and hyperplastic mucin-secreting epithelia are now known to manifest these features [8]. IPMC grows intraductally for a relatively long time. However, the prognosis after stro-mal invasion is bad [9, 10]. Half of invasive carcinomas are mucinous noncystic carcinomas, and most of the others are ordinary tubular adenocarcinomas [11-13]. Cytologic features noninvasive IPMC were first reported in 1989 [14]. Later, it was reported that among sensitivity, specificity and overall accuracy of ultrasonography, ERCP and pancreatic juice cytology of mucin-producing tumors of the pancreas (11 cases), pancreatic juice cytology has achieved the best results [8]. Immunocytochemically, it has been reported that the detection rate using p53 protein (9 IPMC) showed an increase of 23% in comparison with only cytology [15], and the detection rate using telomerase (13 IPMC) showed an increase of 54% in comparison with only cytology [16]. Benign cases (IPM adenoma) were all negative for cytology, p53 protein and telomerase [8, 15, 16]. Namely, the specificity of benign cases was 100% using any of the above

Fig. 1. Arrangement of benign IPMN (hyperplasia), noninvasive IPMC and IDA. a Benign IPMN is papillary and cohesive. Pancreatic ductal brushing, Papanicolaou stain. X400. b Noninvasive IPMC shows a small papillary-cohesive cluster that is accompanied by outer protrusions of cells. Vinyl tube aspiration of the main duct of the resected pancreas, Papanicolaou stain. X400. c IDA is loose, in sheets. Scrap smear, Papanicolaou stain. X400.

Fig. 1. Arrangement of benign IPMN (hyperplasia), noninvasive IPMC and IDA. a Benign IPMN is papillary and cohesive. Pancreatic ductal brushing, Papanicolaou stain. X400. b Noninvasive IPMC shows a small papillary-cohesive cluster that is accompanied by outer protrusions of cells. Vinyl tube aspiration of the main duct of the resected pancreas, Papanicolaou stain. X400. c IDA is loose, in sheets. Scrap smear, Papanicolaou stain. X400.

methods. As for cytological differential diagnosis of noninvasive IPMC and IDA, it was reported to be impossible [17, 18]. It was subsequently reported that they are distingushable [4]. The following describes the cytologic features of noninvasive IPMC and the differences from benign IPMN (hyperplasia/ade-noma) and IDA [4]. Then, we describe noninvasive IPMC with a special type of goblet cells. Lastly, invasive IPMC is described as cases in which the invasive component is a mucinous noncystic carcinoma and cases in which the invasive component is IDAP.

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