Intraductal spread of pancreatic cancer. Clinicopathologic study of 54 pancreatectomized patients

Clinical Relevance of Cancerization of Ducts in Resected Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Although prevalent in 50%-90% of pancreatic ductal adenocarcinomas, the clinical relevance of "cancerization of ducts" (COD) remains unknown.

METHODS

Pathologists retrospectively reviewed slides classifying prevalence of COD. Histopathological parameters, location of first recurrence, recurrence-free survival (RFS), and overall survival (OS) were collected from the institutional pancreatectomy registry.

RESULTS

Among 311 pancreatic ductal adenocarcinomas, COD was present in 216 (69.5%) and more prevalent in the cohort that underwent upfront surgery (75.3% vs 63.1%, P = 0.019). Furthermore, COD was associated with female gender (P = 0.040), advanced T stage (P = 0.007), perineural invasion (P = 0.014), lymphovascular invasion (P = 0.025), and R1 margin (P = 0.009), but not N stage (P = 0.401) or tumor differentiation (P = 0.717). In multivariable regression, COD was associated with less liver recurrence (odds ratio, 0.44; P < 0.005). This association was driven by the cohort of patients who had received preoperative treatment (odds ratio, 0.18; P < 0.001). COD was not predictive for RFS or OS.

CONCLUSIONS

Cancerization of ducts was not associated with RFS or OS. Currently underrecognized, standardized implementation into histopathological reports may have merit, and further mechanistic scientific experiments need to illuminate its clinical and biologic impact.

Pathological survey of precursor lesions in cholangiocarcinoma

BACKGROUND

To clarify the pathological significance of two precursors (high-grade biliary intraepithelial neoplasm [BilIN] and intraductal papillary neoplasm of bile duct [IPNB]) in cholangiocarcinomas (CCAs).

METHODS

Ninety-one cases of CCA (47 distal CCAs [dCCAs], 31 perihilar CCAs [pCCAs] and 13 intrahepatic CCAs of large duct type [LD-iCCAs]) were examined for their association with precursors. Neoplastic intraepithelial lesions without underlying infiltrating carcinoma in the surrounding mucosa of CCAs were considered to reflect high-grade BilIN. High-grade BilIN and IPNB were subdivided into gastric, biliary, intestinal and oncocytic subtypes, while CCAs were subdivided into gastrobiliary, intestinal and oncocytic subtypes. The postoperative overall survival (OS) was examined.

RESULTS

Fifty-four and 8 of 91 CCAs were associated with high-grade BilIN and IPNB, respectively, while these precursors were unidentifiable in the remaining CCAs. A majority of CCAs were of the gastrobiliary subtype, while the intestinal subtype was occasionally detected, and the oncocytic subtype was rare. CCAs with high-grade BilIN showed a similar postoperative OS to CCAs without precursors, while CCAs with IPNB showed a favorable postoperative OS compared to CCAs without precursors.

CONCLUSIONS

CCAs were frequently associated with precursors; high-grade BilIN may be a major precursor and IPNB a minor one. CCAs with IPNB showed a favorable postoperative OS compared to CCAs with high-grade BilIN.

Cell Dissemination in Pancreatic Cancer

Pancreatic cancer is a disease notorious for its high frequency of recurrence and low survival rate. Surgery is the most effective treatment for localized pancreatic cancer, but most cancer recurs after surgery, and patients die within ten years of diagnosis. The question persists: what makes pancreatic cancer recur and metastasize with such a high frequency? Herein, we review evidence that subclinical dormant pancreatic cancer cells disseminate before developing metastatic or recurring cancer. We then discuss several routes by which pancreatic cancer migrates and the mechanisms by which pancreatic cancer cells adapt. Lastly, we discuss unanswered questions in pancreatic cancer cell migration and our perspectives.

Cancerization of ducts in hilar cholangiocarcinoma

Invasive cancers that arise from ductal structures can infiltrate and colonize pre-existing ducts in a process referred to as cancerization of ducts (COD). COD in cholangiocarcinoma is an under-studied process whose clinical significance remains poorly understood. Even though both cancerized ducts and biliary intraepithelial neoplasias (BilINs) show dysplastic changes, hallmarks of COD are (i) an abrupt transition from the normal/reactive epithelium to severe dysplasia and (ii) close proximity to invasive carcinoma with similar cytologic features. We investigated 113 cases of surgically resected hilar cholangiocarcinoma and identified COD in 37 cases (33%). Using immunohistochemistry, we found that COD and adjacent invasive carcinoma had a concordant pattern of p53 and SMAD4 staining in 95% (21/22) and 100% (21/21) of cases, respectively. In contrast, BilINs and cancerized ducts showed significantly lower levels of concordance in p53 and SMAD4 staining at 44% (8/18) and 47% (8/17) of cases, respectively (P = 0.0007 and 0.0001, respectively). By univariate analysis, positive lymph node metastasis (P = 0.027), positive final bile duct margin (P = 0.021), and the presence of COD (P = 0.020) were associated with decreased overall survival. We further performed multivariate analysis to demonstrate that positive lymph node metastasis (P = 0.031), positive final bile duct margin (P = 0.035), and COD (P = 0.0051) were correlated with decreased overall survival. Together, our study highlights that COD is a clinically significant process in hilar cholangiocarcinoma that can be identified using morphological criteria in conjunction with p53 and SMAD4 immunolabeling.

[Intraductal neoplasms of the pancreas]

The latest WHO classification of tumors of the digestive system (2019) has introduced new concepts for the stratification of intraductal neoplasms of the pancreas, mostly based on molecular genetics and malignant potential. Among them, pancreatic intraepithelial neoplasias (PanINs) and intraductal papillary mucinous neoplasms (IPMN) are both precursors of pancreatic ductal adenocarcinoma, whereas intraductal oncocytic papillary neoplasms (IOPN) and intraductal tubulopapillary neoplasms (ITPN) are usually associated with less aggressive subtypes of pancreatic cancer and therefore have a much better prognosis. Hence, it is of utmost importance to correctly classify these lesions and to distinguish them from each other as well as from other nonductal types of neoplasms, which can rarely display an intraductal growth, such as neuroendocrine tumors and acinar cell carcinomas. PanIN are microscopic lesions with limited clinical significance. In contrast, all other intraductal neoplasms can be identified as cystic processes and/or solid tumors by means of imaging, thereby setting an indication for a potential surgical resection. This review presents diagnostically relevant aspects of intraductal neoplasms of the pancreas, which are instrumental for the discussion within interdisciplinary tumor boards (resection vs. watch-and-wait strategies) as well as to determine the extent of resection intraoperatively.

Pre-Operative Imaging and Pathological Diagnosis of Localized High-Grade Pancreatic Intra-Epithelial Neoplasia without Invasive Carcinoma

Pancreatic ductal adenocarcinoma (PDAC) arises from precursor lesions, such as pancreatic intra-epithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN). The prognosis of high-grade precancerous lesions, including high-grade PanIN and high-grade IPMN, without invasive carcinoma is good, despite the overall poor prognosis of PDAC. High-grade PanIN, as a lesion preceding invasive PDAC, is therefore a primary target for intervention. However, detection of localized high-grade PanIN is difficult when using standard radiological approaches. Therefore, most studies of high-grade PanIN have been conducted using specimens that harbor invasive PDAC. Recently, imaging characteristics of high-grade PanIN have been revealed. Obstruction of the pancreatic duct due to high-grade PanIN may induce a loss of acinar cells replaced by fibrosis and lobular parenchymal atrophy. These changes and additional inflammation around the branch pancreatic ducts (BPDs) result in main pancreatic duct (MPD) stenosis, dilation, retention cysts (BPD dilation), focal pancreatic parenchymal atrophy, and/or hypoechoic changes around the MPD. These indirect imaging findings have become important clues for localized, high-grade PanIN detection. To obtain pre-operative histopathological confirmation of suspected cases, serial pancreatic-juice aspiration cytologic examination is effective. In this review, we outline current knowledge on imaging characteristics of high-grade PanIN.

Intraductal pancreatic cancer is less responsive than cancer in the stroma to neoadjuvant chemotherapy

Neoadjuvant chemotherapy (NAC) is often the treatment of choice for borderline resectable and locally advanced invasive pancreatic ductal adenocarcinoma (PDAC); however, most cancers only partially respond to therapy. We hypothesized that the location of residual neoplastic cells in resected specimens following NAC could provide a clue as to the mechanisms of resistance. PDAC cells invade the stroma but can also invade back into and spread via the pancreatic ducts, which has been referred to as "cancerization of ducts" (COD). We compared the responsiveness to chemotherapy between PDAC cells in the stroma and PDAC cells in the duct. Pancreatic resections from a total of 174 PDAC patients (NAC, n = 97; immediate surgery, n = 77) were reviewed. On hematoxylin and eosin sections, COD was identified at the same prevalence in both groups (NAC: 50/97 cases, 52%; immediate surgery: 39/77 cases, 51%; p = 0.879, Fisher's exact test). However, using quantitative image analysis of CK19 immunohistochemistry, we found that the proportion of cancer cells that were intraductal was significantly different between the NAC and immediate surgery groups (median; 12.7% vs. 1.99%, p < 0.0001, Mann-Whitney U test). This proportion was highest in patients with marked therapy responses (36.2%) compared with patients with moderate or poor responses (7.21 & 7.91%). In summary, our data suggest that intraductal components in PDAC are less responsive to chemotherapy than the remainder of the tumor, which could have important implications for therapeutic resistance.

Cancerization of the Pancreatic Ducts: Demonstration of a Common and Under-recognized Process Using Immunolabeling of Paired Duct Lesions and Invasive Pancreatic Ductal Adenocarcinoma for p53 and Smad4 Expression

Invasive pancreatic ductal adenocarcinoma (PDAC) can infiltrate back into and spread along preexisting pancreatic ducts and ductules in a process known as cancerization of ducts (COD). Histologically COD can mimic high-grade pancreatic intraepithelial neoplasia (HG-PanIN). We reviewed pancreatic resections from 100 patients with PDAC for the presence or absence of ducts with histologic features of COD. Features supporting COD included adjacent histologically similar invasive PDAC and an abrupt transition between markedly atypical intraductal epithelium and normal duct epithelium or circumferential involvement of a duct. As the TP53 and SMAD4 genes are frequently targeted in invasive PDAC but not HG-PanIN, paired PDAC and histologically suspected COD lesions were immunolabeled with antibodies to the p53 and Smad4 proteins. Suspected COD was identified on hematoxylin and eosin sections in 89 (89%) of the cases. Immunolabeling for p53 and Smad4 was performed in 68 (76%) of 89 cases. p53 was interpretable in 55 cases and all 55 (100%) cases showed concordant labeling between COD and invasive PDAC. There was matched aberrant p53 immunolabeling in 37 (67%) cases including overexpression in 30 (55%) cases and lack of expression in 7 (13%) cases. Smad4 immunolabeling was interpretable in 61 cases and 59 (97%) cases showed concordant labeling between COD and invasive PDAC. Matched loss of Smad4 was seen in 28 (46%) cases. The immunolabeling of invasive PDAC and COD for p53 and Smad4 supports the high prevalence of COD observed on hematoxylin and eosin and highlights the utility of p53 and Smad4 immunolabeling in differentiating COD and HG-PanIN.

Significance of neoadjuvant chemoradiotherapy for borderline resectable pancreatic head cancer: Pathological local invasion and microvessel invasion analysis

Borderline resectable pancreatic head cancer (BR-PHC) has low resectability due to vascular invasion. Although the clinical effects of neoadjuvant chemoradiotherapy (NAC-RT) for BR-PHC have been examined, few studies have reported its pathological aspects. The present study retrospectively investigated the effect of NAC-RT on the histological features of BR-PHC. A total of 29 patients with BR-PHC who underwent NAC-RT, and 55 controls with resectable PHC, who underwent pancreaticoduodenectomy at the Kurume University Hospital. Tumor staging, lymphovascular invasion (LVI), and microvessel invasion (MVI) were evaluated. The median tumor size in the NAC-RT group was 2.0 cm, and it was smaller than that of the control group (P=0.006). The rates of lymph node metastasis, LVI, and MVI were significantly lower in the NAC-RT group (P<0.001, 0.002, and 0.015, respectively). Overall survival in the NAC-RT group was comparable to that in the control group, although patients with BR-PHC generally had a poorer prognosis than those with resectable PHC. Patients in the NAC-RT group without portal vein invasion (PVI) had a significantly better prognosis than those with PVI in the control group (P=0.002). NAC-RT may be beneficial for patients with BR-PHC by inhibiting local invasion and metastasis as prognosis following resection could be equivalent to that of patients with conventional ductal adenocarcinoma.

Precancerous neoplastic cells can move through the pancreatic ductal system

Most adult carcinomas develop from noninvasive precursor lesions, a progression that is supported by genetic analysis. However, the evolutionary and genetic relationships among co-existing lesions are unclear. Here we analysed the somatic variants of pancreatic cancers and precursor lesions sampled from distinct regions of the same pancreas. After inferring evolutionary relationships, we found that the ancestral cell had initiated and clonally expanded to form one or more lesions, and that subsequent driver gene mutations eventually led to invasive pancreatic cancer. We estimate that this multi-step progression generally spans many years. These new data reframe the step-wise progression model of pancreatic cancer by illustrating that independent, high-grade pancreatic precursor lesions observed in a single pancreas often represent a single neoplasm that has colonized the ductal system, accumulating spatial and genetic divergence over time.

An S100P-positive biliary epithelial field is a preinvasive intraepithelial neoplasm in nodular-sclerosing cholangiocarcinoma

Nodular-sclerosing cholangiocarcinoma (NS-CCA) is a common CCA of the intrahepatic large, perihilar, and distal bile ducts. Intraepithelial biliary neoplasms, such as the mucosal extension of carcinoma and preinvasive neoplastic lesions (ie, biliary intraepithelial neoplasia) reportedly occur in the bile ducts around CCA. In the present study, we collectively refer to these intraepithelial lesions as "intraepithelial neoplasms of the bile duct (IENBs)". We examined the IENBs in 57 surgically resected cases of NS-CCA. S100P immunostaining was used to help detect IENBs. The IENBs formed field(s) of continuous neoplastic biliary epithelial cells and showed a flat, micropapillary, or papillotubular configuration. IENBs could be classified into 3 categories based on their atypia: group A (neoplastic but not enough for malignancy), B (neoplastic and sufficiently well differentiated for high-grade dysplasia), and C (overtly malignant and variably differentiated). IENB was found in 31 of 57 cases, with group C the most common (26 cases) followed by group B (22 cases) and group A (16 cases). The expression of cancer-related molecules and MIB-1 index of groups A and B differed from those of invasive CCA, whereas these features of group C were relatively similar to those of invasive CCA. In conclusion, IENB was not infrequently found in NS-CCA and could be classified into 3 grades. Preinvasive lesions (biliary intraepithelial neoplasias) are likely to be found in groups A and B, whereas cancerization would be included in group C. The classification of IENB may be useful for future studies of the preinvasive intraepithelial neoplastic lesions of NS-CCAs.

A Revised Classification System and Recommendations From the Baltimore Consensus Meeting for Neoplastic Precursor Lesions in the Pancreas

International experts met to discuss recent advances and to revise the 2004 recommendations for assessing and reporting precursor lesions to invasive carcinomas of the pancreas, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm, and other lesions. Consensus recommendations include the following: (1) To improve concordance and to align with practical consequences, a 2-tiered system (low vs. high grade) is proposed for all precursor lesions, with the provision that the current PanIN-2 and neoplasms with intermediate-grade dysplasia now be categorized as low grade. Thus, "high-grade dysplasia" is to be reserved for only the uppermost end of the spectrum ("carcinoma in situ"-type lesions). (2) Current data indicate that PanIN of any grade at a margin of a resected pancreas with invasive carcinoma does not have prognostic implications; the clinical significance of dysplasia at a margin in a resected pancreas with IPMN lacking invasive carcinoma remains to be determined. (3) Intraductal lesions 0.5 to 1 cm can be either large PanINs or small IPMNs. The term "incipient IPMN" should be reserved for lesions in this size with intestinal or oncocytic papillae or GNAS mutations. (4) Measurement of the distance between an IPMN and invasive carcinoma and sampling of intervening tissue are recommended to assess concomitant versus associated status. Conceptually, concomitant invasive carcinoma (in contrast with the "associated" group) ought to be genetically distinct from an IPMN elsewhere in the gland. (5) "Intraductal spread of invasive carcinoma" (aka, "colonization") is recommended to describe lesions of invasive carcinoma invading back into and extending along the ductal system, which may morphologically mimic high-grade PanIN or even IPMN. (6) "Simple mucinous cyst" is recommended to describe cysts >1 cm having gastric-type flat mucinous lining at most minimal atypia without ovarian-type stroma to distinguish them from IPMN. (7) Human lesions resembling the acinar to ductal metaplasia and atypical flat lesions of genetically engineered mouse models exist and may reflect an alternate pathway of carcinogenesis; however, their biological significance requires further study. These revised recommendations are expected to improve our management and understanding of precursor lesions in the pancreas.

Surgical and oncological impact of main pancreatic duct spread in invasive ductal adenocarcinoma: A clinicopathological study of 184 resected cases

BACKGROUND/OBJECTIVES

This study examined main pancreatic ductal spread in invasive ductal adenocarcinoma (IDC) of the pancreas.

METHODS

Data from IDC patients who underwent radical surgery from 1990 to 2013 in our hospital were examined retrospectively. Incidence of intraductal spread of pancreatic cancer (IS), distance from the tumor edge, direction of IS and clinicopathological factors associated with the presence of IS were retrospectively examined with data from IDC patients who underwent radical surgery.

RESULTS

Among 260 IDC patients who underwent surgery, 184 eligible cases, IS was identified in 42 patients (22.8%) and mean length of IS was 18.7 ± 21.6 mm. Mean distances on the ampullary and distal sides of IS were 11.1 mm and 11.6 mm. IS was significantly more frequent in localized tumors (UICC T1-2 vs. 3-4, p = 0.007), with tumor diameter ≤2 cm (p = 0.034) and in cases with scarce microscopic perineural invasion (p = 0.047). Among patients who underwent pancreaticoduodenectomy and distal pancreatectomy, IS presence (11.6 vs. 21.8%), mean distance to the contralateral side (11.4 vs. 11.6 mm), and IS ≥ 2 cm (3.3 vs. 4.7%) showed no significant differences. Overall survival did not differ significantly between IS-positive and -negative patients in the full analysis set or propensity score-matched patients (42 matched pairs).

CONCLUSIONS

In setting resectional margins at 2 cm, a small proportion of cases (3.8%) showed positive surgical margins. Localized tumor (UICC: T1-2, or <2 cm in diameter) requires more care with surgical margins, warranting intraoperative frozen sections.

Poor prognosis of common-type invasive ductal carcinomas that originate in the branching pancreatic duct

PURPOSE

To clarify the incidence, clinicopathological features and prognosis of pancreatic invasive ductal carcinomas (IDCs) with different tumor origin sites in the pancreatic duct.

METHODS

Based on the relationship between the invasive cancer area (ICA) and the main pancreatic duct (MPD), IDCs less than 2 cm in diameter were classified into two groups: type I, in which the ICA and MPD were separated, and type II, in which the MPD passed through the ICA. The clinicopathological findings and prognosis of each type were compared in a total of 37 patients.

RESULTS

The incidences of IDC types I and II were 18.9 and 81.1 %, respectively. Although there was no difference in local invasion, both node involvement and venous invasion tended to occur more frequently in type I IDC, and the three-year survival rate was significantly lower for type I (28.6 %) than type II (71.8 %) IDC.

CONCLUSIONS

The prognosis of IDCs that originated in the branching pancreatic duct (BPD) distant from the MPD (type I) was worse than the prognosis of IDCs that originated in either the MPD or the BPD close to the MPD (type II). These data suggest that the progression and degree of malignancy of IDCs may vary depending on the site of tumor origin in the pancreatic duct.

Clinicopathologic study of intrapancreatic cancer spread in carcinoma of the body and tail of the pancreas

OBJECTIVE

The aims of this study were to clarify the type of intrapancreatic spread of cancer of the pancreatic body and tail and to assess whether a 2-cm transection margin is adequate to ensure negative margins.

METHODS

We selected 66 patients who underwent distal pancreatectomy for cancer of the pancreatic body and tail. We investigated intrapancreatic cancer spread in these patients histopathologically and analyzed the relationship between 2-cm-margin positivity and other clinicopathological characteristics.

RESULTS

Two-centimeter-margin positivity was observed in 17 cases. In these, tumors had a tendency to spread toward the pancreatic head along the main pancreatic duct. As a result of statistical analysis, we considered venous invasion (odds ratio [OR], 15.48; 95% confidence interval [CI], 1.61-148.94; P = 0.0177), 2-cm-margin fibrosis (OR, 173.88; 95% CI, 8.96-3375.03; P = 0.0007), and 2-cm-margin hardness (OR, 5.97; 95% CI, 1.07-33.46; P = 0.0420) as being independently related to 2-cm-margin positivity.

CONCLUSIONS

The results suggest that 2 cm is not a safe length to ensure a negative margin. In the future, preoperative and intraoperative evaluation of the degree of fibrosis of pancreatic parenchyma could lead to cancer-free pancreatic cut-end margins.

Lateral spread along the main pancreatic duct in branch-duct intraductal papillary-mucinous neoplasms of the pancreas: usefulness of intraductal ultrasonography for its evaluation

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMN) of the pancreas tend to spread intraepithelially along the pancreatic duct wall. We evaluated histopathological intraductal lateral spread (LS) along the main pancreatic duct (MPD) from branch-duct IPMN and investigated the usefulness of intraductal ultrasonography (IDUS) for its preoperative diagnosis.

PATIENTS AND METHODS

Twenty-four patients with branch-duct IPMN who had undergone preoperative IDUS and surgery were reviewed clinicopathologically. The prevalence and histological length of LS along the MPD from branch-duct IPMN, characteristics of the patients with LS, and efficacy of LS assessment by IDUS were examined.

RESULTS

LS along the MPD was observed in 54% of the subjects. In the group of patients with LS, its mean length was 25.2±16.8mm (5-50mm) and the diameter of the MPD was 6mm or greater. Of the patients with LS, those in whom the length of LS along the MPD was longer than the diameter of the cystically dilated branch accounted for 30%. The diameter of the MPD in the group with LS was significantly greater than that in the group without LS (P=0.03). The sensitivity, specificity, and overall accuracy of IDUS in the detection of LS were 92%, 91%, and 92%, respectively.

CONCLUSION

LS along the MPD was detected in about half of the resected cases of branch-duct IPMN. Preoperative transpapillary IDUS may be beneficial for the determination of the resection line, especially in those branch-duct IPMN patients in whom the MPD is 6 mm or greater in diameter.

Invasive ductal carcinoma of the pancreas tail with noninvasive growth through the nondilated main pancreatic duct and macroscopically cystic invasive carcinomatous glands

Noninvasive growth forming macroscopically dilated cystic pancreatic ducts is a fundamental feature of intraductal papillary mucinous neoplasm (IPMN), from which invasive carcinomas can arise. However, some invasive ductal carcinomas of the pancreas also show a macroscopically cystic feature. We experienced 2 cases of invasive ductal carcinoma of the pancreas tail with noninvasive growth through the main pancreatic duct without dilation at the body side, and with collection of macroscopically cystic carcinomatous glands infiltrating at the spleen side, which resembled some IPMNs and/or IPMN-derived invasive carcinomas. These cases were different from IPMN in that they lacked macroscopic dilatation of the pancreatic ducts, and the macroscopically dilated cystic carcinomatous glands were invasive but not intraductal. The intraductal component of the carcinomas showed papillary growth of neoplastic epithelia with atypia consistent with PanIN-3. Both intraductal and invasive components predominantly showed gastric mucin phenotype (MUC5AC+, MUC6 focally +, MUC2- or MUC2+ in scattered small number of cells). Recognition of these pancreatic carcinoma cases is important in the following 2 points: (1) The presence of such cases should always be kept in mind as differential diagnosis of IPMN or IPMN-derived invasive carcinoma in imaging and pathologic diagnoses. (2) The histogenesis of these cases might be placed in the intermediate between 2 major histogenetic pathways of pancreatic carcinoma, that is, one from microscopic precursors called PanIN and the other from macroscopic precursors of IPMN. These cases can be regarded as invasive carcinomas derived from semimacroscopic extension of the intraductal lesion of the main pancreatic duct.

Multi-centric pancreatic cancer without PanIN lesion

The patient was a 67-year-old man under follow-up after gastric cancer surgery. An abdominal CT scan performed 1 year earlier had shown an approximately 14-mm hypovascular mass in the pancreatic body; however, he did not consent to treatment and was followed up for 1 year. A blood workup showed that the fasting blood glucose level, which had been within normal limits, was elevated to 174 mg/dl (normal, 70-109 mg/dl), and the HbA1c level was 12.0% (normal, 4.3-5.8%). Abdominal CT revealed an approximately 20-mm mass in the pancreatic body and an approximately 12-mm mass in the pancreatic tail, and magnetic resonance imaging cholangiopancreatography (MRCP) showed discontinuity of the main pancreatic duct (MPD). Since these findings led to the suspicion of invasive ductal carcinoma (IDC) of the pancreas developing in the pancreatic body and tail, we performed distal pancreatectomy with splenectomy. Histologically, IDCs were observed in the pancreatic body and tail. However, PanIN was not observed in the MPD between the two carcinomas. They were diagnosed as independent invasive ductal carcinomas of the pancreas.

Pancreatic intraepithelial neoplasia revisited and updated

Most pancreatic neoplasms are classified as ductal adenocarcinoma because they show a ductal phenotype, making a ductal origin very likely. The duct lesions that may give rise to pancreatic ductal adenocarcinoma have been called pancreatic intraepithelial neoplasia (PanIN). A classification system for these lesions distinguishes between three grades of PanIN. Molecular studies revealed that PanIN-2 and PanIN-3 lesions represent a distinct step towards invasive carcinoma. While high-grade PanINs are extremely rare in the normal pancreas, low-grade PanINs are common in individuals older than 40 years and may be associated with lobular fibrosis and intraductal papillary mucinous neoplasms of the gastric type. This disease spectrum has also been described in members of kindreds with familial pancreatic cancer. The natural history and cause of PanINs are unknown. As PanIN-1 lesions entail little risk, while PanIN-3 lesions are high-risk lesions, it would be of interest to target PanIN-2 lesions, which can be regarded as the starting point of progressive neoplastic changes that lead to invasive pancreatic ductal adenocarcinoma. Global gene expression analysis identified several differentially expressed genes which show enhanced expression in PanINs and may be used as potential biomarkers to facilitate diagnosis and therapy.

Growth process of small pancreatic carcinoma: A case report with imaging observation for 22 months

This report describes serial observations of the growth process of a small invasive ductal carcinoma (IDC) of the pancreas from imaging studies. Histopathological studies showed IDC with macroscopic retention cysts proximal to an intraductal papillary-mucinous adenoma with mild atypia of the branch duct type in the pancreatic body, with no relation between the two lesions. IDC was demonstrated as an extremely low-echoic mass resembling a cyst with an unclear margin on the initial endoscopic ultrasonography. We misinterpreted the low-echoic mass as a benign intraductal mucinous-papillary neoplasm (IPMN) based on findings of other imaging studies, and the patient was followed-up. The mass increased from 7 mm to 13 mm in diameter over 22 mo, and remained smaller than 10 mm in diameter for about 420 d. The tumor volume doubling time was 252 d. The Ki67 labeling index was 15.9%, similar to that described in previous reports. Hence, IDC may grow slowly while remaining small.

Review of the cytologic features of noninvasive ductal carcinomas of the pancreas: differences from invasive ductal carcinoma

Invasive ductal adenocarcinoma (IDA) of the pancreas (IDAP) originating from the ductal gland has a poor prognosis. Noninvasive carcinomas are principally intraductal papillary mucinous carcinomas (IPMCs) and pancreatic intraepithelial neoplasms 3 (PanIN-3). Small papillary-cohesive clusters, individually well-enveloped nuclei in well-preserved cytoplasm, centrally located nuclei, small nuclei (about 10 mum), euchromatin, clearly defined cell borders, small cytoplasm without prominent anisocytosis and no cytoplasm more than 21 mum in shortest diameter, a mixture of goblet cells, and a pleomorphic aspect are common in IPMC and intraductal papillary mucinous neoplasm (IPMN), whereas malignancy in nuclei are observed only in IPMC. PanIN-3 cells have small papillary-cohesive and compact clusters, a monomorphic aspect, and small dense cytoplasm and are highly suggestive of malignancy. IDA cells have loose sheet and solid clusters, poorly preserved cytoplasm, nuclei that tend to adhere to each other, large nuclei, a combination of large nuclei (short diameter <15 mum) with hyperchromatin, a monomorphic aspect, and abundant cytoplasm more than 21 mum in the shortest diameter. To preoperatively differentiate noninvasive IPMC and PanIN-3 from IDAP, these features would be clinically very useful.

Clinicopathological study on the intraductal spread of small pancreatic cancer

BACKGROUND

The aim of this study was to evaluate histopathologically the frequency, direction, and length of intraductal spread (IS) along the main pancreatic duct from the main tumor of small pancreatic cancer.

METHODS

Resected specimens from 20 cases of pTS1 (histologically 2 cm or less in diameter) pancreatic cancer (September 1983 to December 2005) were examined histopathologically. As controls, 40 resected specimens from cases of pTS2 (more than 2 cm and less than 4 cm in diameter) or larger sized pancreatic cancer (pTS2<or=) were examined in the same manner. The specimens were evaluated histopathologically as to (1) the prevalence of IS, (2) the direction and length of IS, and (3) the positive rates of transpapillary cytology of pure pancreatic juice (TPC) and biopsy of the main pancreatic duct (TPB), performed preoperatively.

RESULTS

IS was observed in 45% of pTS1 and 13% of pTS2<or= cases. In 88% of cases of pTS1, IS was observed in the direction of the ampullary side. In 40% of cases of pTS2<or=, IS toward the ampullary side was seen. The mean length of IS in pTS1 and pTS2<or= cases was 11.8 mm and 7.2 mm, respectively. Positive rates of TPC and TPB in pTS1 cases were 70% and 75%, respectively, and in pTS2<or= cases, 50% and 44%, respectively.

CONCLUSIONS

The frequency of IS was high in pTS1 cases, which suggests there is potential for improvement in establishing the histocytological diagnosis of small pancreatic cancer via the transpapillary approach with the development of adequate tools.

Pancreatic intraepithelial neoplasia in heterotopic pancreas: evidence for the progression model of pancreatic ductal adenocarcinoma

Morphologic, clinical, and genetic evidence suggests that pancreatic intraepithelial neoplasia (PanIN) is a precursor to ductal adenocarcinoma. But understanding precursor lesions in a pancreas with existing tumor is hampered by the fact that chronic pancreatitis often accompanies carcinoma, and the possible interactions between tumor, chronic pancreatitis, and PanIN are complex. Furthermore, cancerization of ducts can mimic high-grade PanIN. Heterotopic pancreas has a genetic make-up, physiologic function, and local environmental exposure similar to that of the pancreas. It offers an opportunity to study putative precursor lesions in a setting with fewer confounding factors. We identified 6 pancreatic cancer patients who had heterotopic pancreas removed at the time of surgery. All 6 cases were immunostained for p53, cyclin D1, and p16. Molecular analysis of K-ras mutation was also done. All 6 cancer-associated heterotopias had PanIN-1A or 1B; 5 had PanIN-2 and 1 had PanIN-3. Three of 6 cases harbored the same K-ras codon 12 mutation as the PanINs in orthotopic pancreas, and a similar pattern of p53, cyclin D1, and p16 expression was observed between heterotopic and orthotopic pancreas in all 6 cases. There was no chronic pancreatitis in the cancer-associated heterotopias, but chronic pancreatitis was seen adjacent to carcinoma in 5 of 6 cases. The presence of PanIN in heterotopic pancreas from patients with ductal adenocarcinoma supports the progression model.

Distribution of intraductal lesions in small invasive ductal carcinoma of the pancreas

AIMS

To investigate the distribution of intraductal lesions in small invasive ductal carcinoma (IDC) of the pancreas.

METHODS

In 21 cases with IDCs microscopically < or = 20 mm in diameter, the intraductal lesions around a mass were studied histologically and mapped according to the pancreatic intraepithelial neoplasia (PanIN) classification.

RESULTS

PanIN-3, PanIN-2, PanIN-1B and PanIN-1A were found in 17, 10, 20 and 21 of 21 cases, respectively, and were divided into lesions in adjacent and distal areas, respectively defined as within and beyond 10 mm from the mass as follows: 100% (17/17), 100% (10/10), 95.0% (19/20) and 90.5% (19/21) in the former, while 23.5% (4/17), 50.0% (5/10), 90.0% (18/20) and 95.2% (20/21) in the latter. PanIN-3 lesions were predominantly found in the area adjacent to the mass. In some cases, significant PanIN-3 appeared to show a consecutive geographic extension around the mass via the main pancreatic duct (MPD). The distance of PanIN-3 spread was within 25 (mean 10.5) mm from the mass edge. PanIN-2 lesions were found in the area adjacent to the mass and discontinuous with the mass or PanIN-3 lesions. PanIN-1B and PanIN-1A tended mainly to exist sporadically throughout the entire pancreas. In the MPD, PanIN-3 was found in 14 (82.4%) of 17 cases and in 36 (32.1%) of 112 lesions, which was most frequent in intraductal lesions.

CONCLUSIONS

PanIN-3 lesions might be an intraductal extension of the main tumor. The resection margin of 25 mm, at least longer than 11 mm, from the mass edge will be necessary.

Invasive ductal adenocarcinoma of the pancreas may originate from the larger pancreatic duct: a study of 13 tumors less than 2 cm in diameter

BACKGROUND/PURPOSE

We aimed to elucidate the origin/primary site of invasive ductal adenocarcinoma of the pancreas, based on the distribution of intraductal carcinoma components. These components were identified by a mural elastic fiber cuff.

METHODS

Thirteen specimens from patients with invasive ductal adenocarcinoma (microscopically, less than 2 cm in diameter) of the pancreas were studied histopathologically. Variants of invasive ductal adenocarcinoma and intraductal papillary-mucinous carcinoma were excluded.

RESULTS

Intraductal carcinoma components of invasive ductal adenocarcinoma were found in 12 of the specimens 13 (92%), and were observed within the tumor mass and/or on its boundary, or outside the tumor mass. Intraductal components were characterized by low papillary projections lacking a fibrovascular core, with/without surrounding tubular structures, or by irregular stratification and pleomorphism of the epithelial cells. Invasive components mostly showed a tubular pattern with desmoplasia. The distribution of the intraductal components in the 12 specimens was as follows: in 9 (75%), they were in both the main pancreatic duct and large branch ducts; and in 3, they were in the smaller branch ducts only.

CONCLUSIONS

Invasive ductal adenocarcinomas of the pancreas may originate most frequently from the main pancreatic duct or larger branch ducts, while the smaller ducts are less often the site of cancer origin.

Histopathological study of invasive ductal carcinoma (IDC) of the pancreas without associated cancerous occlusion of the main pancreatic duct

BACKGROUND/PURPOSE

[corrected] Invasive ductal carcinoma (IDC) of the pancreas may be associated with cancerous occlusion of the main pancreatic duct (MPD) in its growth process, but at quite low a frequency; there are patients who do not develop this occlusion.

METHODS

This study examined the histological features of surgical specimens from 8 patients with IDC without MPD occlusion, in comparison to 32 patients with IDC with this occlusion (controls). The pancreatic duct was identified by confirming the presence of mural elastic fibers on the wall of the pancreatic duct. Immunohistochemical staining was done with Ki-67 antibody.

RESULTS

The frequency of IDC without MPD occlusion was very low (5.0% [2/40] patients at Kurume University and 3.1% [4/126] patients at Juntendo University). The number of intraductal carcinoma components was 1.5 +/- 1.1 per specimen in the IDCs without occlusion and 5.9 +/- 2.4 in the controls (P < 0.001). The Ki-67 labeling index was 18.0 +/- 11.7% in the IDCs without occlusion and 30.0 +/- 12.1% in the controls (P < 0.05). The number of intraductal carcinoma components and the Ki-67 labeling index were significantly lower in the IDCs without occlusion than in the controls.

CONCLUSIONS

Our findings suggested that these two types of IDC could have different biological features.

Intraductal low papillary histological pattern of carcinoma component shows intraductal spread in invasive carcinoma of the pancreas

BACKGROUND/PURPOSE

We attempted to discriminate between carcinoma in situ (CIS) and the intraductal invasion/cancerization of invasive ductal carcinoma (IDC) of the pancreas, by comparing the histological patterns of the intraductal components and those of venous invasion.

METHODS

Specimens from 30 patients with IDC were examined histopathologically. Intraductal components and blood vessel invasion in IDC were assessed in specimens stained with hematoxylin & eosin and elastica van Gieson (EVG).

RESULTS

Intraductal components of IDC were found in 28 of the 30 cases of IDC, in 261 ducts, and in 2.3 ducts per one section of one case, on average. The intraductal components of IDC were classified into three histological patterns, as follows: low papillary (including flat), tubular (including solid and cribriform), and mixed (low papillary plus tubular). The incidences of the low papillary, tubular, and mixed patterns in the 261 ducts, were 39% (102 ducts), 56% (145 ducts), and 5% (14 ducts), respectively. The histological pattern of venous invasion was tubular in all but 1 of the 26 cases, and this 1 case showed low papillary patterns as well as a tubular pattern.

CONCLUSIONS

A tubular pattern of intraductal components in IDC of the pancreas indicates intraductal invasion, while a low papillary pattern indicates CIS or carcinoma in another location to which it has spread.

Mucin expression profile is related to biological and clinical characteristics of intraductal papillary-mucinous tumors of the pancreas

OBJECTIVES

Biologic and clinical characteristics of intraductal papillary-mucinous tumors of the pancreas (IPMTs) were studied in reference to immunohistochemical mucin (MUC1, MUC2, and MUC5AC) expression.

METHODS

Histologic grade, immunohistochemical ki-67 and p53 expression, and findings in imaging tests of 21 IPMTs (9 carcinomas, 6 borderline tumors, and 6 adenomas) were examined according to the mucin expression profile.

RESULTS

IPMTs were divided into groups: M1 group (MUC1+, n = 4), M2 group (MUC2 + MUC1-, n = 12), and M5 group (MUC5AC + MUC1-MUC2-, n = 5). The M2 group was subdivided into M2s (strongly positive) and M2w (weakly positive) groups. The rates of carcinoma in the M1, M2s, M2w, and M5 groups were 100%, 40%, 0%, and 0%, respectively. The Ki-67 labeling indexes were significantly higher in the M1 and M2s groups. p53 staining was positive in 50% and 40% of the IPMTs in the M1 and M2s groups, respectively, but in none of the IPMT in the M2w and M5 groups. Morphologic changes in imaging tests during the observation periods were most remarkable in the M1 group.

CONCLUSIONS

Our results suggest that MUC1 is related to malignant character but MUC5AC alone is related to benign character in IPMTs and that malignant potential of IPMTs expressing MUC2 depends on the degree of MUC2 expression.

Intestinal and oncocytic variants of pancreatic intraepithelial neoplasia. A morphological and immunohistochemical study

We report 2 previously undescribed morphological variants of pancreatic intraepithelial neoplasia (PanIN). The first variant with an intestinal phenotype was associated with mucinous carcinomas that occurred in the tail of the pancreas of 2 men (60 and 65 years old). The carcinomas lacked the characteristic ovarian-like stroma of mucinous cystic neoplasms observed in female patients and did not show a papillary architecture. Whether they represent mucinous cystadenocarcinomas or mucinous carcinomas that arose from the flat variant of intraductal papillary mucinous neoplasms could not be determined with certainty. Microscopically, the intestinal type of PanIN was composed of pseudostratified columnar cells similar to those of colonic adenomas and showing variable degrees of dysplasia. A significant increase in the MIB-1 labeling index correlated with the severity of dysplasia. In contrast to conventional PanIN, the intestinal variant expressed MUC-2 and was MUC-1 negative. The second type of PanIN had an oncocytic phenotype, coexpressed MUC-2 and MUC-1 mucins, and was associated with intraductal oncocytic papillary carcinomas that showed a similar immunohistochemical mucin profile. Both intestinal and oncocytic types of PanIN expressed DPC4 and lacked p53 reactivity. The anatomical separation of the PanINs from the carcinomas and the gradual progression of cytological and architectural abnormalities in both variants of PanIN argue against ductal spread (cancerization of the ducts). The intestinal and oncocytic variants of PanIN broaden the morphological spectrum of this intraductal lesion. Although their significance is unknown, the possibility that these PanIN variants represent cancer precursors should be considered.

Intraductal tubular neoplasms of the pancreas: histogenesis and differentiation

OBJECTIVES

Intraductal neoplasms of the pancreas are generally referred to as intraductal papillary mucin-producing neoplasms (IPMNs), according to the WHO classification system. Herein, we report that morphologic and immunohistochemical features of intraductal tubular carcinoma (ITC) are quite different from those of intraductal papillary mucinous carcinoma (IPMC).

METHODS

We analyzed histogenesis and differentiation of ITC by light microscopy and immunohistochemistry.

RESULTS

Histologically, ITC was characterized as an intraductal nodular appearances with a monotonous tubular growth pattern without papillary projection. ITC showed de novo-like appearance without sequential progression usually observed in IPMC, suggesting that ITC is a homogeneous neoplasm. Cuboidal tumor cells in ITC resembled normal pancreatic duct epithelia, and the characteristic growth pattern of ITC replaced that of normal pancreatic duct epithelium. Immunohistochemically, ITC cells were positive for MUC-1 on the apical side of the cell membrane. In contrast to ITC cells, IPMC cells were negative for MUC-1, and ductal adenocarcinoma cells were strongly positive for MUC-1, as was the stroma around the cancer. The immunohistochemical staining pattern of DUPAN-2 resembled that of MUC-1. Interestingly, localization of MUC-1 and DUPAN-2 staining in ITC cells was similar to that in normal pancreatic ductules. ITC cells were negative for MUC-2 and MUC-5AC. In contrast, most IPMC cells were positive for MUC-2 and MUC-5AC.

CONCLUSION

Based on our histologic and immunohistochemical findings, the intraductal pancreatic neoplasm (IPN) can be classified into 2 groups: IPN with gastrointestinal differentiation and IPN with pancreatic duct differentiation. Our present data indicated that ITC cells may arise directly from duct epithelia without progression and possessed pancreatic duct differentiation. On the basis of our data, we suggest that classification of pancreatic neoplasms in the WHO and The Armed Forces Institute of Pathology (AFIP) systems should be reconsidered.

Distribution of elastic fiber in tissues of normal stomach, stomach ulcer and stomach carcinoma

AIM: To study the distribution of elastic fiber (EF) in tissues of normal stomach, gastric ulcer and gastric carcinoma.

METHODS: Tissue samples, including 40 cases of stomach carcinoma, 17 cases of normal stomach and 7 cases of stomach ulcer, were studied using hematoxylin and eosin (HE) staining and EF staining. The distributions of EF were analyzed under light microscope.

RESULTS: In tissues of stomach ulcer, EF, with a deep staining, was mainly located in the muscularis mucosa adjacent to the ulcer lesion. No EF was observed in carcinoma zone, but a great amount was found in the smooth muscle and connective tissue around the lesion. EF was increased significantly in stomach carcinoma specimens, compared with that in normal tissues (P = 0.0042). Hyperplasia of small vessel endothelia was observed in cancer tissues but not in ulcer tissues.

CONCLUSION: The distribution patterns of EF are different in normal stomach, gastric ulcer and gastric carcinoma. The increase of EF in gastric ulcer may be related to the stimulation of chronic inflammation; while in carcinoma, in addition to the chronic inflammatory stimulation, the EF increase in the surrounding tissues may also result from augmented EF production triggered by the cancer cells indirectly through releasing stimulatory factors or directly via regulating gene expression in EF-producing cells. The increase of EF in the stomach wall lesion is a chronic process.

An illustrated consensus on the classification of pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasms

Invasive pancreatic ductal adenocarcinoma is an almost uniformly fatal disease. Several distinct noninvasive precursor lesions can give rise to invasive adenocarcinoma of the pancreas, and the prevention, detection, and treatment of these noninvasive lesions offers the potential to cure early pancreatic cancers. Noninvasive precursors of invasive ductal adenocarcinoma of the pancreas include pancreatic intraepithelial neoplasias (PanINs), intraductal papillary mucinous neoplasms (IPMNs), and mucinous cystic neoplasms. Diagnostic criteria, including a distinct ovarian-type stroma, and a consistent nomenclature are well established for mucinous cystic neoplasms. By contrast, consistent nomenclatures and diagnostic criteria have been more difficult to establish for PanINs and IPMNs. Because both PanINs and IPMNs consist of intraductal neoplastic proliferations of columnar, mucin-containing cells with a variable degree of papilla formation, the distinction between these two classes of precursor lesions remains problematic. Thus, considerable ambiguities still exist in the classification of noninvasive neoplasms in the pancreatic ducts. A meeting of international experts on precursor lesions of pancreatic cancer was held at The Johns Hopkins Hospital from August 18 to 19, 2003. The purpose of this meeting was to define an international acceptable set of diagnostic criteria for PanINs and IPMNs and to address a number of ambiguities that exist in the previously reported classification systems for these neoplasms. We present a consensus classification of the precursor lesions in the pancreatic ducts, PanINs and IPMNs.