Laparoscopy and peritoneal cytology in the staging of pancreatic cancer

Staging laparoscopy in patients with pancreatic cancer allows identification of metastatic disease which is beyond the resolution of computed tomography. Laparoscopic ultrasound, dissection, and/or peritoneal cytology may be used to enhance the sensitivity of the staging procedure. Our experience at Massachusetts General Hospital with staging laparoscopy and peritoneal cytology over the past 8 years (N = 239) reveals that approximately 30% of patients without metastases by computed tomography harbor occult metastatic disease at laparoscopy. Additionally, published series demonstrate accurate determination of resectability in greater than 75% of patients after staging laparoscopy. Staging laparoscopy in patients with pancreatic cancer allows optimization of resources and avoidance of unnecessary surgery.

Unilateral hydronephrosis resulting from intraluminal obstruction of the ureter by adenosquamous endometrioid carcinoma arising from disseminated endometriosis

A case of adenosquamous carcinoma arising in the background of disseminated pelvic endometriosis presented as unilateral hydronephrosis and a polypoid intraluminal ureteral mass. This is the first case of a malignancy arising in endometriosis presenting as an obstructive ureteral mass. The patient had a history of total hysterectomy and bilateral salpingo-oophorectomy 5 years earlier because of an endometriotic cyst, and had since been under unopposed estrogen replacement therapy. An analysis of the case and related literature is presented. Possible pathogenic mechanisms are discussed.

Grading the invasive component of urothelial carcinoma of the bladder and its relationship with progression-free survival

Although grading is valuable prognostically in pTa and pT1 papillary urothelial carcinoma, it is unclear whether it provides any prognostic information when applied to the invasive component in muscle-invasive carcinoma. The authors analyzed 93 cases of muscle-invasive urothelial carcinoma of the bladder treated with radical cystectomy for which follow-up information was available. Each case was graded using the Malmström grading system for urothelial carcinoma, applied to the invasive component. Pathologic stage, lymph node status, and histologic invasion pattern were also recorded and correlated with progression-free survival. Thirty-four cases (37%) were pT2, 40 (43%) were pT3, and 19 (20%) were pT4. Of the 77 patients who had a lymph node dissection at the time of cystectomy, 34 (44%) had metastatic carcinoma to one or more lymph nodes. The median survival for pT2, pT3, and pT4 stages was 85, 24, and 29 months, respectively (p = 0.0001). Lymph node-negative and lymph node-positive patients had a median survival of 63 and 23 months, respectively (p = 0.0001). Fifteen patients (16%) were graded as 2b and 78 patients (84%) were graded as 3. Median survival of patients graded as 2b was 34 months compared with 31 months for patients graded as 3 (p value not significant). Three invasive patterns were recognized: nodular (n = 13, 14%), trabecular (n = 39, 42%), and infiltrative (n = 41, 44%). The presence of any infiltrative pattern in the tumor was associated with a median survival of 29 months, compared with 85 months in tumors without an infiltrative pattern (p = 0.06). Pathologic T stage and lymph node status remain the most powerful predictors of progression in muscle-invasive urothelial carcinoma. In this group of patients histologic grade, as defined by the Malmström system and as applied to the invasive component, provided no additional prognostic information. An infiltrative growth pattern may be associated with a more dismal prognosis.

Effect of matrix metalloproteinase inhibition on pancreatic cancer invasion and metastasis: an additive strategy for cancer control

OBJECTIVE

To investigate the effect of a matrix metalloproteinase (MMP) inhibitor, BB-94, on the viability, invasion, and metastases of pancreatic cancer.

SUMMARY BACKGROUND DATA

Inhibitors of MMPs, enzymes that degrade extracellular matrix, have been tested as single chemotherapeutic agents for pancreatic cancer.

METHODS

Capan1 and AsPC1 cell lines were studied. BB-94 cytotoxicity was evaluated by cell proliferation assays. Production of MMP2 and MMP9 in conditioned media was demonstrated by gelatin zymography. The in vitro effect of BB-94 on cell invasion was assayed using invasion chambers. Hepatic metastases from pancreatic cancer were induced by intrasplenic injections of Capan1 or AsPC1 cells in nude mice. The in vivo effect of BB-94 on liver metastases was evaluated by comparing animals receiving BB-94 treatment with controls receiving vehicle alone. Variables measured included death rate and tumor burden (liver-to-body weight ratio).

RESULTS

BB-94 was not cytotoxic between 3 and 3,000 ng/mL. Zymography demonstrated production of MMP2 and MMP9 by both cell lines, with complete inhibition of these enzymes by BB-94 at 48 ng/mL. Invasion chamber assays showed that BB-94 (48-400 ng/mL) impeded cell invasion in vitro compared with untreated controls. In vivo, BB-94 prevented death or reduced the death rate from hepatic metastases in animals injected with Capan1 or AsPC1 cells. BB-94 treatment resulted in significant reductions in hepatic tumor burden compared with untreated controls.

CONCLUSIONS

Inhibition of MMP reduces both growth of pancreatic cancer metastases and the death rate. These actions do not reflect cytotoxicity but rather result from impaired cancer cell attachment, migration, and organ invasion. MMP inhibitors may provide an additive effect to cytotoxic agents in multidimensional treatment regimens for pancreatic cancer.

Impact of laparoscopic staging in the treatment of pancreatic cancer

HYPOTHESIS

Staging laparoscopy in patients with pancreatic cancer identifies unsuspected metastases, allows treatment selection, and helps predict survival.

DESIGN

Inception cohort.

SETTING

Tertiary referral center.

PATIENTS

A total of 125 consecutive patients with radiographic stage II to III pancreatic ductal adenocarcinoma who underwent staging laparoscopy with peritoneal cytologic examination between July 1994 and November 1998. Seventy-eight proximal tumors and 47 distal tumors were localized.

INTERVENTIONS

Based on the findings of spiral computed tomography (CT) and laparoscopy, patients were stratified into 3 groups. Group 1 patients had unsuspected metastases found at laparoscopy and were palliatedwithout further operation. Group 2 patients had no demonstrable metastases, but CT indicated unresectability due to vessel invasion. This group underwent external beam radiation with fluorouracil chemotherapy followed in selected cases by intraoperative radiation. Patients in group 3 had no metastases or definitive vessel invasion and were resection candidates.

MAIN OUTCOME MEASURE

Survival.

RESULTS

Staging laparoscopy revealed unsuspected metastases in 39 patients (31.2%), with 9 having positive cytologic test results as the only evidence of metastatic disease (group 1). Fifty-five patients (44.0%) had localized but unresectable carcinoma (group 2), of whom 2 (3.6%) did not tolerate treatment, 20 (36.4%) developed metastatic disease during treatment, and 21 (38.2%) received intraoperative radiation. Of 31 patients with potentially resectable tumors (group 3), resection for cure was performed in 23 (resectability rate, 74.2%). Median survival was 7.5 months for patients with metastatic disease, 10.5 months for those receiving chemoradiation, and 14.5 months for those who underwent tumor resection (P = .01 for group 2 vs. group 1; P<.001 for group 3 vs group 1).

CONCLUSIONS

Staging laparoscopy, combined with spiral CT, allowed stratification of patients into 3 treatment groups that correlated with treatment opportunity and subsequent survival. Among the 125 patients, laparoscopy obviated 39 unnecessary operations and irradiation in patients with metastatic disease not detectable by CT. Laparoscopic staging can help focus aggressive treatment on patients with pancreatic cancer who might benefit.

Outcome of pancreaticoduodenectomy with pylorus preservation or with antrectomy in the treatment of chronic pancreatitis

OBJECTIVE

To compare the short- and long-term results of pancreaticoduodenectomy with pylorus preservation (PPPD) or with antrectomy (Whipple procedure) in the treatment of selected patients with chronic pancreatitis.

BACKGROUND

PPPD may be preferred over Whipple because of its purported nutritional advantages and the reduced likelihood of postgastrectomy syndromes.

METHODS

A retrospective review was performed of 72 consecutive patients undergoing pancreaticoduodenectomy for chronic pancreatitis between 1991 and 1997.

RESULTS

PPPD was performed in 39 patients and Whipple in 33. The two patient populations had similar characteristics. Short-term complications included (PPPD vs. Whipple): pancreatic or biliary fistulas (5.1% vs. 15%), delayed gastric emptying (33% vs. 12%), cholangitis (2.6% vs. 6.1%), and death (0 vs. 3%). Delayed gastric emptying was not associated with other complications and resulted in longer hospital stays for PPPD than for Whipple patients (15 vs. 12 days). The duration of follow-up averaged 41 +/- 24 months. Long-term weight status was similar, with body-mass indices of 22.1 and 22.9 after PPPD and Whipple, respectively. Postoperative enzyme supplementation (63% vs. 77%) and new-onset diabetes (10% vs. 12%) did not differ significantly between the PPPD and Whipple groups. Dumping, bile gastritis, or peptic ulcer disease occurred in three patients after PPPD and in three after Whipple. Complete or partial pain relief was attained in 60% and 70% of patients after PPPD and Whipple, respectively. Multivariate analysis of preoperative variables revealed that site-specific pathology in the head of the pancreas was the only independent factor associated with successful pain relief after pancreatic resection.

CONCLUSION

PPPD results in higher frequencies of postoperative delayed gastric emptying compared with the Whipple procedure. Both operations achieve comparable long-term nutritional results, cause new insulin dependence in surprisingly few patients, and provide equivalent pain relief to 65% of selected patients. Patients with disproportionate pathology in the head of the pancreas have a higher likelihood of successful pain relief.

Histopathologic analysis of chromosome aneuploidy in ductal carcinoma in situ

Formalin-fixed, paraffin-embedded sections from 28 cases of ductal carcinoma in situ (DCIS; 12 with coexisting invasive neoplasm) were analyzed for numerical alterations of chromosomes 7, 8, 16, and 17 by performing fluorescence in situ hybridization (FISH) using centromeric (alpha-satellite) probes. Based on signal counts in 200 to 300 nuclei, each hybridization was classified as disomic (copy loss in <40%, copy gain in < 10%), monosomic (copy loss in at least 50% of nuclei, partial if 40% to 49%) or trisomic/polysomic (copy gain in at least 20% of nuclei, partial if 10% to 19%). Grade I lesions were characterized by complete lack of significant chromosome gain, but 29% showed partial (focal) monosomy. Grade III lesions, in contrast, showed partial or complete trisomy/polysomy in 88% of hybridizations versus monosomy in only 4%. Grade II DCIS exhibited a mixed pattern of chromosome aneuploidy: 38% hybridizations were disomic, 36% trisomic/polysomic, and 26% monosomic (8 of 10 hybridizations showing complete monosomy occurred in grade II lesions). Disomic hybridizations exhibiting rare cells (5% to 10%) with copy gain were more frequent in tumors with coexisting invasive neoplasm (5 of 17 v 2 of 33, P = .02). In morphologically heterogeneous lesions, higher-grade foci were characterized by chromosome copy gain relative to corresponding lower-grade areas in 17 of 22 (77%) hybridizations. These results show the presence of multiple (at least 3) distinct chromosome aneuploidy patterns in DCIS, in keeping with divergent mechanisms of genetic alteration. Degree of chromosomal instability, moreover, may correlate with progression of DCIS to invasive growth, implying that genetic instability is a parameter that impacts the likelihood of early breast carcinoma progression.

Clinicopathologic Significance of Ductal Carcinoma in situ in Breast Core Needle Biopsies With Invasive Cancer

To assess whether the presence and amount of intraductal component (IC) in diagnostic needle core biopsies (NCB) is predictive of an extensive IC (EIC), the authors evaluated 50 invasive ductal carcinomas diagnosed with NCB, and then excised via lumpectomy, with regard to the extent of IC in both the NCB and subsequent lumpectomy specimen. These parameters were compared with each other and with the lumpectomy margin status. Extent of IC in the NCB was evaluated by dividing the number of ducts that contained IC by the total number of tissue cores. A ratio of more than 0.5 was considered EIC (EICc). IC extent in the lumpectomy was established by estimating the percentage of the tumor corresponding to IC and was considered extensive (EIC(L)) if more than 25% and if there was presence of IC away from the invasive tumor. The mean size of resected tumors was 1.6 +/- 0.7 cm. In 29 cases (58%) there was no IC in the NCB (NegICc), 11 cases (22%) exhibited nonextensive IC (NEICc), and 10 cases (20%) demonstrated EICc. A total of 7%, 36%, and 70% of the NegICc, NEICc, and EICc cases respectively had EIC(L)(p < 0.0001). The presence of EIC(L) correlated significantly with close or positive margin status for in situ disease (EIC(L) positive, 12 of 13 [92%] vs EIC(L) negative, 11 of 37 [30%]; p = 0.004). None of the NegICc, 27% of NEICc, and 40% of EICc had a positive margin for in situ neoplasm in the lumpectomy specimen (p = 0.004), and 24%, 18%, and 50% had positive margins for invasive neoplasm (p = not significant). The authors conclude that EICc predicts EIC(L) and constitutes a risk factor for positive lumpectomy margin status-particularly for in situ tumor. EICc may thus be of clinical value in identifying a subset of patients that requires a wider local excision.

pT1 urothelial carcinoma of the bladder: criteria for diagnosis, pitfalls, and clinical implications

One of the challenging areas in genitourinary pathology is the recognition of early invasion in urothelial neoplasia. Not uncommon, the patterns of invasion into lamina propria are subtle because a desmoplastic response is absent. Tangential sectioning due to inability to orient transurethral resection of bladder tumor specimens, crush and cautery artifacts further compound this problem. This review is presented to familiarize surgical pathologists with the criteria and different patterns of lamina propria invasion by urothelial carcinoma. Problems and pitfalls associated with the recognition of invasion and the clinicopathologic significance of lamina propria invasive urothelial cancer are also discussed.

Determination of Her-2/Neu status in breast carcinoma: comparative analysis of immunohistochemistry and fluorescent in situ hybridization

Her-2/neu (H2N) status in breast carcinoma has been considered a prognostic factor that may have therapeutic implications; however, the correlation between H2N overexpression and gene amplification has not been completely defined. A consecutive series of ductal carcinomas (34 invasive and 7 in situ) were analyzed by fluorescent in situ hybridization for H2N gene and chromosome 17 copy number using touch preps of intact cells and by immunohistochemistry, using three different commercial antibodies to H2N protein (Zymed, clone 31G7; Ventana, clone CB11; and Dako, polyclonal) in corresponding formalin-fixed, paraffin-embedded tissue sections. Gene amplification was classified as unequivocal if more than five signals were present in more than 80% of the counted nuclei and absent if more than 80% of the nuclei counted contained two or fewer gene copies. Cases that did not fulfill the above criteria were considered equivocal for amplification. Immunostaining was classified as follows: 0 = no staining; 1+ = faint, incomplete membranous pattern; 2+ = moderate, complete membranous pattern; 3+ = strong membranous pattern. Of the 34 invasive tumors, 10 (29%) had unequivocal gene amplification. Furthermore, all had more than 10 copies of the gene in more than 60% of the counted nuclei. An additional nine cases (26%) had equivocal amplification, which was usually the result of chromosome 17 aneuploidy (seven of nine) or heterogeneity. With the Zymed and Dako antibodies, all tumors with 3+ staining had unequivocal gene amplification and all cases with 2+, 1+, or 0 staining were negative or equivocal for gene amplification. With the Ventana antibody, all cases with 3+ staining had unequivocal gene amplification, but two cases with unequivocal amplification by fluorescent in situ hybridization exhibited 1+ staining. Moderate (2+) H2N staining was observed in one case, three cases, and five cases with the Ventana, Dako, and Zymed reagents, respectively, and did not correlate with H2N gene copy number. Discordance between H2N and chromosome 17 copy number was not a useful means of defining amplification. Two cases of ductal carcinoma in situ with the Zymed antibody and two with the Dako antibody showed 3+ staining despite lack of unequivocal gene amplification. We conclude that (1) strong H2N immunostaining is highly associated with gene amplification, although there is minor variation in sensitivity between different antibodies; (2) a subset of breast carcinomas (3 to 15%) demonstrate moderate H2N staining without evidence of amplification, and it is unclear whether they represent highly sensitive staining or are a subset of cases that show overexpression without amplification; (3) gene amplification, as detected by fluorescent in situ hybridization, is associated with at least 10 gene copies per nucleus, and lower gene copy duplication (3 to 4/nucleus) is frequent, usually the result of chromosome 17 polysomy, and not associated with high-level overexpression; (5) overexpression of H2N without amplification may be more frequent in ductal carcinoma in situ, implying a different role in the biology of preinvasive versus invasive neoplasm.

Trypsin and activation of circulating trypsinogen contribute to pancreatitis-associated lung injury

Pancreatic proteases are secreted in acute pancreatitis, but their contribution to associated lung injury is unclear. Applying models of mild edematous (intravenous caerulein) and severe necrotizing (intraductal glycodeoxycholic acid) pancreatitis in rats, we showed that both trypsinogen and trypsin concentrations in peripheral blood, as well as lung injury, correlate with the severity of the disease. To isolate the potential contribution of proteases to lung injury, trypsin or trypsinogen was injected into healthy rats or trypsinogen secreted in caerulein pancreatitis was activated by intravenous enterokinase. Pulmonary injury induced by protease infusions was dose dependent and was ameliorated by neutrophil depletion. Trypsinogen activation worsened lung injury in mild pancreatitis. In vitro incubation of leukocytes with trypsinogen showed that stimulated leukocytes can convert trypsinogen to trypsin. In conclusion, this study demonstrates that the occurrence and severity of pancreatitis-associated lung injury (PALI) corresponds to the levels of circulating trypsinogen and its activation to trypsin. Neutrophils are involved in both protease activation and development of pulmonary injury.

Sequential accumulation of K-ras mutations and p53 overexpression in the progression of pancreatic mucinous cystic neoplasms to malignancy

OBJECTIVE

Pancreatic mucinous cystic neoplasms (MCNs) provide a spectrum of neoplastic changes ranging from benign to malignant. The authors have correlated K-ras mutations and p53 overexpression with the evolution of these tumors.

METHODS

Areas of mild, moderate, or severe dysplasia were microdissected from paraffin-embedded tissue sections of 28 different MCNs (10 benign, 9 borderline, 9 malignant). Nonneoplastic pancreatic ducts were also microdissected from tissues adjacent to the tumors. Ten serous cystadenomas served as negative controls. K-ras codon 12 mutations were identified by a mutant-enriched nested polymerase chain reaction-restriction fragment length polymorphism assay and confirmed by sequencing. p53 overexpression was demonstrated by immunohistochemistry.

RESULTS

K-ras mutations were detected in 20% of benign, 33% of borderline, and 89% of malignant MCNs. Histologically, mutations were found in 26% (7/27) of MCN epithelia with mild dysplasia, 38% (5/13) of MCN epithelia with moderate dysplasia, and 89% (8/9) of MCN epithelia with severe dysplasia or carcinoma. Ten percent (4/39) of nonneoplastic pancreatic ducts at the margins of MCN harbored mutations, all associated with borderline or malignant tumors. Overexpression of p53 occurred in none of the benign or borderline MCNs but in 44% (4/9) of the malignant tumors (p = 0.006 benign/borderline vs. malignant). p53 immunoreactivity was concentrated in areas of severe dysplasia/carcinoma or invasion, where K-ras mutation had been detected.

CONCLUSION

These findings demonstrate a sequential accumulation of genetic changes in the carcinogenesis of MCN. K-ras mutations appear early and increase in proportion with increasing dysplasia. Overexpression of p53 is a late finding observed only in carcinomas, and in combination with mutated K-ras genes. The presence of K-ras mutations in nonneoplastic ducts supports formal pancreatic resection over enucleation for treatment. Mucinous cystic neoplasms may be a useful model to study the evolution of pancreatic ductal adenocarcinomas, in which precursor lesions remain unknown.

Multidrug resistance phenotype in high grade soft tissue sarcoma: correlation of P-glycoprotein immunohistochemistry with pathologic response to chemotherapy

BACKGROUND

P-glycoprotein-mediated drug efflux has been implicated as an important mechanism of multidrug resistance (MDR) in cancer. Its role in chemotherapy resistance in soft tissue sarcoma is unclear.

METHODS

Tumor specimens prior to and following neoadjuvant chemotherapy from 29 cases of high grade soft tissue sarcoma were analyzed with 2 monoclonal antibodies (C494 and JSB-1) that recognize different epitopes of P-glycoprotein. Staining intensity was graded 0 = negative, 1 = equivocal, 2 = moderate, 3 = strong. Only cases with Grade 2 or 3 staining intensity with both antibodies were considered MDR positive. The resection specimens were evaluated for tumor necrosis postchemotherapy. Pathologic response was graded as good for <15%, moderate for 15-50%, or poor for >50% posttreatment tumor viability.

RESULTS

Of the 29 pretreatment specimens, 10 (34%) were MDR positive and 19 (66%) were MDR negative. Pathologic response to treatment was characterized as good in 6, moderate in 7, and poor in 16 patients. Of the MDR positive biopsies, 9 (90%) had poor response, compared with 7 (36%) in the MDR negative biopsy group (P = 0.0078). None of the cases with MDR positive biopsies had a good response, compared with 6 cases in which biopsies were MDR negative (32%) (P = 0.057). Only one MDR negative case became MDR positive posttreatment.

CONCLUSIONS

Expression of MDR phenotype is found in approximately one-third of high grade soft tissue sarcomas. These preliminary data show a significant correlation between MDR phenotype and poor pathologic response to chemotherapy, and suggest that MDR induction by chemotherapy in soft tissue sarcoma is an uncommon event.

Interstitial trypsinogen release and its relevance to the transformation of mild into necrotizing pancreatitis in rats

BACKGROUND & AIMS

Intracellular activation of trypsinogen is currently believed to initiate pancreatitis. Factors responsible for the progression of mild to necrotizing pancreatitis are poorly understood. This study evaluated the significance of interstitial protease release and activation in this process.

METHODS

In rats with cerulein-induced pancreatitis, concentrations of trypsinogen and its activation peptide TAP were measured in lymph and blood, and pancreatic injury was determined. Activation of extracellular trypsinogen was induced by intravenous infusion of enterokinase, which does not enter the acinar cell. Gabexate mesilate (acinar cell permeable) or soybean trypsin inhibitor (acinar cell nonpermeable) was administered to distinguish the effects of intracellular or extracellular protease activation.

RESULTS

In cerulein pancreatitis, trypsinogen levels increased prominently and were highest in lymph and portal vein blood, whereas TAP increments were modest. Combined cerulein/enterokinase infusions resulted in marked TAP increases in lymph and blood and in severe necrohemorrhagic pancreatitis. Gabexate mesilate as well as soybean trypsin inhibitor significantly decreased TAP levels in both lymph and blood and reduced pancreatic injury, with no significant differences between groups.

CONCLUSIONS

In secretagogue-induced pancreatitis, large amounts of trypsinogen are present in the interstitium and drain via the portal and lymphatic circulation. Activation of this extracellular trypsinogen induces hemorrhagic necrosis in a setting of mild edematous pancreatitis. This phenomenon may be the central event in the progression to fulminant necrotizing pancreatitis.

Chemotactic peptide uptake in acute pancreatitis: correlation with tissue accumulation of leukocytes

Chemotactic peptides bind specifically to receptors on leukocyte membranes. This property makes them prospective vehicles to evaluate inflammation and infection. We used two well-established models of acute pancreatitis to quantitate the binding of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine-lysine (fMLFK) to leukocytes and its correlation to degree of organ inflammation. Uptake of the (99m)Tc-labeled nicotinyl hydrazine-derivatized chemotactic peptide analog fMLFK-HYNIC was measured in blood, pancreas, lung, and muscle specimens in rats with edematous or necrotizing pancreatitis and was compared with neutrophil sequestration assessed by myeloperoxidase activity and histology. Chemotactic peptide uptake in the pancreas was increased in mild and severe pancreatitis compared with controls, with higher levels in severe than in mild disease, and correlated with tissue myeloperoxidase activity (r = 0.7395, P < 0.001). Increased pulmonary uptake only in severe pancreatitis reflected pancreatitis-induced neutrophil sequestration in the lungs. Muscle uptake was unchanged compared with controls. Edema formation did not affect chemotactic peptide uptake. The data suggest that uptake of chemotactic peptides can contribute to quantitative assessment of neutrophils in localized inflammatory processes and is independent of associated edema formation or microcirculatory compromise.

Immunohistochemical characterization of pancreatic tumors induced by dimethylbenzanthracene in rats

Dimethylbenzanthracene (DMBA) induces pancreatic adenocarcinomas in rats 9 months after carcinogen exposure, with precursor lesions (tubular complexes) developing 1 month after initiation of treatment. Because previous studies have suggested an acinar cell of origin for these tumors, we investigated the expression pattern of ductal, acinar, and islet cell markers in these cancers to gain insight into their phenotype and cell of origin. Pancreatic neoplasms were induced in rats by implantation of DMBA into the head of the pancreas. Lesions studied included 10 early tubular complexes (DMBA for 2 weeks), 8 tubular complexes (DMBA for 1 month), and 10 adenocarcinomas (DMBA for 9 months). Normal rat pancreas served as a control. For comparison, 5 human ductal adenocarcinomas were also evaluated. Immunohistochemistry with ductal (keratin, cytokeratin 19, cytokeratin 20), acinar (chymotrypsin), and islet (chromogranin A) cell markers was performed to analyze the tissues. Rat tubular complexes and adenocarcinomas revealed strong expression of keratin, cytokeratin 19, and cytokeratin 20 in the cytoplasm of all neoplastic cells, absence of chymotrypsin, and rare immunoreactivity to chromogranin A. Human adenocarcinomas showed strong expression of keratin and cytokeratin 19 in all neoplastic cells, expression of cytokeratin 20 in 5-20% of cells, and absence of chymotrypsin and chromogranin A. Pancreatic adenocarcinomas induced by DMBA in rats express markers consistent with a ductal phenotype, as observed in human tumors. Ductal marker expression in early tumor stages suggests a ductal cell of origin.

Clinicopathologic analysis of microscopically invasive breast carcinoma

Breast biopsy or mastectomy cases having diagnoses of carcinoma in situ with "microinvasion," "minimal invasion," "focal invasion," or "suggestive of invasion" were reviewed and all histologically identified foci of invasive disease from each case were measured using an ocular micrometer. Cases in which any single focus of invasion was greater than 5 mm or the added size of separate invasive foci exceeded 10 mm were excluded, resulting in a study group of 75 patients. Invasive neoplasm was present in the initial biopsy in 69 of 75 cases (92%); however, residual invasive neoplasm was found in the subsequent lumpectomy/mastectomy from 14 of these (20%). In 59% of cases, two or more histologically separate foci of invasion were identified. Invasive foci consisted of isolated cells or cell clusters, each less than 1 mm (microfocal invasion), in 33% of cases. In 12 cases, the sum of individual invasive foci was 5 to 10 mm. Axillary lymph nodes (LN) from 5 of 69 patients (7%) contained metastatic carcinoma (four cases, one LN positive; one case, two LN positive). The cumulative sizes of all invasive foci in the LN-positive group were microfocal invasion (one case), 0.6 mm (one case), 1.1 mm, 2.5 mm, and 5.8 mm. The difference in frequency of axillary node metastasis between tumors with microfocal and measurable invasion (4.3% v 8.6%) was not statistically significant. Follow-up data were available on 55 cases (mean interval, 66.1 months). One (node-negative) patient had duct carcinoma in situ recurrence in the same breast 4 years after initial treatment. Another (with unknown node status) developed an axillary lymph node metastasis 13 months after initial treatment (96% disease-free survival). We conclude that microscopic stromal invasion in breast carcinoma, at least in the setting of significant in situ component, is often initiated from multiple foci. Patients with microscopically invasive breast carcinoma have a small but significant risk of axillary metastases, although a highly favorable survival.

Development of gastrointestinal beta2-microglobulin amyloidosis correlates with time on dialysis

Dialysis-associated beta2-microglobulin (beta2m) amyloidosis affects predominantly musculoskeletal tissue, but visceral involvement also occurs. To evaluate the clinical significance and prevalence of gastrointestinal beta2m amyloidosis, we studied hemodialysis patients admitted for gastrointestinal-related complaints. Hemodialysis patients (excluding those with non-beta2m amyloidosis) who were admitted with gastrointestinal complaints from 1984 to 1994 were identified. Gastrointestinal tissues from patients with available autopsy or surgical specimens were examined using hematoxylin and eosin stain, Congo red stain, and beta2m immunostain. Each case was evaluated independently by two pathologists and scored for quantity and location of beta2m amyloid and associated pathology. Of 24 patients, eight (four men and 4 women) had beta2m amyloid deposits within the gastrointestinal tract. Acute clinical presentation ranged from abdominal pain to gastrointestinal bleeding and was not significantly different for patients with or without gastrointestinal beta2m amyloid deposits. However, the mean time on dialysis of 15.3 +/- 5.7 years (range 6-24 years) for patients with gastrointestinal beta2m amyloidosis was significantly greater than that of patients without gastrointestinal beta2m amyloidosis (10.5 +/- 7.0 years, range <1 to 22 years, p < 0.05). Vascular histopathology ranged from mild focal thickening of vessel walls to massive vascular beta2m amyloid deposition with thrombosis. Extravascular beta2m amyloid ranged from mild to severe with marked expansion of the submucosa. Mucosal pathology ranged from none to severe ulceration. The degree of beta2m amyloid and the associated pathology tended to increase in severity with time on dialysis. Gastrointestinal beta2m amyloid deposition is an underappreciated complication of chronic hemodialysis that is significantly associated with increased time on dialysis. Gastrointestinal beta2m amyloidosis should be considered in any patient on hemodialysis 10 years or more who has gastrointestinal symptoms and can be identified in resection specimens as well as some biopsy specimens. Congo red stain and beta2m immunostains may be necessary for sensitive histopathologic evaluation of gastrointestinal beta2m amyloidosis.

Role of brush border Na+/H+ exchange in canine ileal absorption

Na+/H+ exchanger isoforms have been identified in mammalian intestinal enterocytes and cloned: NHE1 on the basolateral membrane regulating intracellular pH; and NHE2 and NHE3 on the brush border serving transcellular absorption in Na+. NHE1 and NHE2 are much more sensitive to inhibition by amiloride than NHE3, their in vitro IC50s for amiloride being 1 microM, 1 microM and 39 microM, respectively. This study tested the hypothesis that the brush border NHE3 isoform plays the predominant role in basal and meal-stimulated ileal absorption. Absorption studies (N = 72) were performed in dogs with 25-cm ileal Thiry-Vella fistulae. Six groups were studied over 4 hr. Perfusion with [14C]PEG and 140 mM Na+ was used to calculate absorption of water, ions, and glucose. Luminal amiloride was administered from the second to the fourth hours at doses of 20 microM in groups 3 and 4 to inhibit NHE1 and NHE2, and 1mM in groups 5 and 6 to also inhibit NHE3. A 480-kcal canine meal was ingested after the second hour in groups, 2, 4, and 6. Meal ingestion was followed by significant increases in water and electrolyte absorption. Amiloride (1 mM) caused significant reductions in basal and meal-stimulated ileal absorption, while the 20 microM dose had no effect on either. These data are consistent with the hypothesis that NHE3, but not NHE2, is involved in basal and meal-stimulated ileal water and Na+ absorption.

Luminal dopamine modulates canine ileal water and electrolyte transport

Previous studies have suggested that dopamine stimulates active ileal ion absorption via alpha 2-adrenergic or dopaminergic receptor activation. Identification of a dopamine 1a receptor on rat enterocytes located in intestinal crypts prompted this investigation of the effect of luminally administered dopamine on water and ion transport in the canine ileum. Absorption studies (n = 27) were performed in dogs with 25-cm ileal Thiry-Vella fistulas. Perfusion with [14C] PEG was used to calculate absorption of water and electrolytes from the Thiry-Vella fistula. Experiments consisted of three 1-hr periods: basal, luminal drug infusion at 10(-4) M, and recovery. Agonists used included dopamine (DOP: alpha-adrenergic, D1 and D2 receptor) and SKF 38393 (D1 receptor). Antagonists used included terazosin (TZ: alpha 1) and yohimbine (YOH: alpha 2). DOP caused significant increases in water and electrolyte absorption. TZ and YOH prevented the dopamine-induced proabsorptive response. Luminal DOP may serve as a proabsorptive modulator of ileal transport, acting via alpha 1, alpha 2, and dopaminergic receptors. The development of more potent proabsorptive dopamine analogs, which maintain the ability to broadly activate mucosal receptors, may be useful in such clinical situations as diabetic diarrhea, short gut syndrome, or following small bowel transplantation.

Endogenous nitric oxide promotes ileal absorption

BACKGROUND/AIMS

Nitric oxide (NO) is generated in vascular endothelium and enteric neural plexuses from L-arginine by the action of nitric oxide synthase (NOS). This study tested the hypothesis that NO is a modulator of ileal water and ion transport.

METHODS

NADPH diaphorase staining was performed on fixed frozen sections of canine ileum. Absorption studies (n = 80) were performed in five dogs with 25-cm ileal Thiry-Vella fistulas (TVF). Perfusion with [14C]PEG was used to calculate absorption of water, ions, and glucose from the TVF. Experiments comprised three 1-hr periods: basal, drug infusion, and recovery. Drugs infused luminally at 5 x 10(-4) mol/liter included L-ARG (NOS substrate), L-NAME (NOS inhibitor), L-ARG/L-NAME combination, D-ARG (inactive enantiomer of L-ARG), L-LYS (basic amino acid control for L-ARG), and SNAP (NO donor).

RESULTS

NADPH diaphorase staining indicated NOS activity in the ileal mucosa and submucosa. L-ARG and SNAP caused significant increases in water and ion absorption, whereas L-NAME caused significant decreases. The prosecretory effect of L-NAME was completely reversed by synchronous L-ARG. D-ARG and L-LYS had no significant effects. No infused agent influenced [14C]PEG recovery.

CONCLUSIONS

Inhibition of endogenous NO synthesis by L-NAME causes a prosecretory response for water and ions, which can be reversed by the administration of NOS substrate L-ARG. These results are consistent with the hypothesis that endogenous NO maintains a proabsorptive influence on water and ion transport in the ileum.