The vast majority of pancreatic carcinomas are primary, and, among these, more than 90% are of ductal origin. However, a variety of extrapancreatic tumors may involve the pancreas secondarily and may manifest different clinicopathological characteristics and outcomes. In this study, pathology material from 973 surgical specimens and 4955 adult autopsy cases was reviewed to identify the tumors metastatic to or secondarily involving the pancreas. Biliary and periampullary neoplasms and tumors confined to peripancreatic soft tissue were excluded. In the autopsy series, the pancreas was involved by tumor in 190 cases, and 81 of these were secondary tumors. These were predominantly of epithelial origin, most commonly from lung (34), followed by GI tract (20), kidney (4), breast (3), liver (2), ovary (1), and urinary bladder (1). In addition, there were six tumors of hematopoietic origin, two melanomas, two sarcomas, and two mesotheliomas. Among the 973 surgical specimens, 38 cases contained metastatic tumors to the pancreas. Of these, 11 were lymphomas, and the others were carcinomas of stomach (7), kidney (6), lung (2), liver, prostate, ovary, uterus (1 case of each), and a Merkel cell carcinoma. In addition, there were three malignant gastrointestinal stromal tumors and one retroperitoneal leiomyosarcoma. In conclusion, lung cancer is the most common source of metastasis to pancreas, followed by gastrointestinal carcinomas and lymphomas. These tumors are usually seen in patients with disseminated disease and are detected mainly in autopsies. Secondary tumors constitute about 4% of pancreatic specimens in the authors' surgical database. Approximately one-third of them are clinically mistaken as primary tumors of the pancreas. These are predominantly hematopoietic malignancies or carcinomas of renal or gastric origin. Secondary tumors should be entertained in both the clinical and pathological differential diagnosis of pancreatic neoplasia.
Emerging evidence suggests a dichotomy in the dysplasia-CIS-invasive carcinoma sequence in the pancreas. Pancreatic intraepithelial neoplasms (PanINs; small, incidental duct lesions) progress to invasive ductal adenocarcinomas (5-y survival of <15%), whereas intraductal papillary mucinous neoplasms (large, intraductal tumors with ductal dilatation) are often associated with colloid carcinoma (5-y survival of >55%). We explored the relationship of these lesions by examining the expression of MUC1 and MUC2, glycoproteins reportedly reflecting "aggressive" and "indolent" phenotypes in pancreas cancer, respectively. Immunohistochemical labeling with MUC1 (clone Ma695) and MUC2 (clone Ccp58) antibodies was performed on PanINs (n ؍ 43), intraductal papillary mucinous neoplasms (n ؍ 74), ductal adenocarcinomas (n ؍ 136), and colloid carcinomas (n ؍ 15). Fifty-four percent of the intraductal papillary mucinous neoplasms expressed MUC2, whereas none of the PanINs did. In contrast, PanINs, especially higher grade lesions, were often positive for MUC1 (61% of PanIN 3), whereas the expression of this glycoprotein was infrequent in intraductal papillary mucinous neoplasms (20%). This dichotomy was further accentuated in the invasive carcinomas with which these two preinvasive pathways are respectively associated: all colloid carcinomas were MUC2؉ (100%) and MUC1؊ (0%), whereas the labeling pattern was the reverse for ductal adenocarcinomas: 63% were MUC1؉ and only 1% were MUC2؉. These results support a dichotomy in the dysplasia-CIS sequence in the pancreas. Because these two pathways often lead to different types of invasive carcinomas, this is an invaluable model for the study of carcinogenesis. The findings here also support the previous impression that MUC2 (the mucin associated with gel formation) is a marker of the "indolent" pathway (intraductal papillary mucinous neoplasm and colloid carcinoma), whereas MUC1 (the glycoprotein known to have an inhibitory role in cell-cell and cell-stroma interactions as well as in immunoresistance of tumor cells) is a marker of the "aggressive" pathway (PanIN to ductal adenocarcinoma). The vast majority of pancreatic neoplasms are ductal adenocarcinomas, characterized morphologically by invasive tubular units that are often associated with a dense desmoplastic stroma. Ductal adenocarcinomas are among the most lethal cancers, with an overall 5-year patient survival rate of Ͻ5% (1-3). As is true for other epithelial malignancies, ductal adenocarcinomas are believed to arise from morphologically distinct precursor lesions (4 -12). A uniform nomenclature and standardized diagnostic criteria for these precursor lesions have recently been adopted, and the accepted terminology is now pancreatic intraepithelial neoplasia (PanIN; 13). KEY WORDS: Carcinogenesis
Invasive micropapillary carcinoma (IMPCa) of breast is histologically characterized by growth of cohesive tumor cell clusters within prominent clear spaces resembling dilated angiolymphatic vessels. In this study, eighty three breast carcinomas with IMPCa differentiation were identified by review of the invasive carcinoma cases in our institution and correlated retrospectively with standard clinicopathologic parameters and survival status relative to a control series of cases (mean follow up 7 years). IMPCa growth pattern was present in 6% of all breast carcinomas; it was generally a focal component in otherwise typical invasive ductal carcinoma. It comprised more than 80% of the total neoplasm in only 10 cases (12%), 50 -80% of the neoplasm in 7 cases (8%), 20 -50% of the neoplasm in 22 cases (26%) and less than 20% in 44 cases (53%). The mean tumor size was 4 cm, 22% invaded skin, and 58% were poorly differentiated, but 71% were ER positive. Axillary node metastases were present in 77% of cases, were typically multiple (51% had three or more positive), and usually contained an IMPCa component (81% of the cases). There was no significant difference in node status, ER status, size, tumor grade, or peritumoral angiolymphatic invasion between tumors with predominant (more than 50%) v/s focal IMPCa components. In both groups 46% of the patients died from their disease (mean interval to death ؍ 36m). Skin involvement and nodal status were the only parameters which predicted poor survival (P ؍ .01). The outcome of patients with IMPCa did not differ significantly from infiltrating ductal carcinomas of similar node status. In conclusion, our results suggest that IMPCa growth pattern may be a manifestation of aggressive behavior, as shown by frequent skin invasion and extensive nodal involvement. However, clinicopathologic features and outcome of IMPCa are not strongly dependent on the relative amount of micropapillary component.
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