Preoperative computed tomography scan to predict pancreatic fistula after distal pancreatectomy using gland and tumor characteristics.

BACKGROUND: Preoperative risk stratification for postoperative pancreatic fistula in patients undergoing distal pancreatectomy is needed. METHODS: Risk factors for postoperative pancreatic fistula in 220 consecutive patients undergoing distal pancreatectomy at 2 major institutions were recorded retrospectively. Gland density was measured on noncontrast computed tomography scans (n = 101), and histologic scoring of fat infiltration and fibrosis was performed by a pathologist (n = 120). RESULTS: Forty-two patients (21%) developed a clinically significant pancreatic fistula within 90 days of surgery. Fat infiltration was significantly associated with gland density (P = .0013), but density did not predict pancreatic fistula (P = .5). Recursive partitioning resulted in a decision tree that predicted fistula in this cohort with a misclassification rate less than 15% using gland fibrosis (histology), density (HU), margin thickness (cm), and pathologic diagnosis. CONCLUSIONS: This multicenter study shows that no single perioperative factor reliably predicts postoperative pancreatic fistula after distal pancreatectomy. A decision tree was constructed for risk stratification.

MUC expression in hyperplastic and serrated colonic polyps: lack of specificity of MUC6.

Previous studies have shown that hyperplastic and serrated polyps of the colon show variable degrees of gastric and intestinal differentiation. MUCs are a class of approximately 20 genes that encode high-molecular-weight glycoproteins, or mucopolysaccharides, that are widely expressed in epithelial cells and show organ specificity. The role of MUC in serrated carcinogenesis is unknown. One previously published study suggested that expression of MUC6 is specific for sessile serrated adenoma/polyps (SSA/Ps) and thus can be used to distinguish these lesions from hyperplastic polyps (HPs). However, data from our group suggest that MUC antibodies are not reliable in this differential diagnosis. The aims of this study were to systematically evaluate the expression of MUCs in serrated colon polyps and to determine the efficacy of MUC expression in differentiating HPs from SSA/Ps specifically. Routinely processed specimens from 182 serrated polyps [58 HPs, 46 SSA/Ps, 59 SSA/Ps with dysplasia (SSA/P-D), 19 traditional serrated adenomas, and 38 conventional tubular or tubulovillous adenomas (CAs)] were immunohistochemically stained with MUC1, MUC2, MUC5AC, and MUC6, and scored for extent, intensity, and location of staining within the polyps. HPs were further subclassified into goblet cell type (N=18), microvesicular type (N=21), and mucin-depleted type (N=19). The data were compared between the different polyp groups and between polyps from different anatomic locations in the colon. MUC1, MUC2, MUC5AC, and MUC6 were expressed in 27%, 100%, 100%, and 72% of serrated polyps overall. These antibodies were positive in 32%, 100%, 100%, and 43% of CAs. Expression levels of MUC1, MUC2, and MUC5AC were not significantly different between any of the polyp subgroups or between serrated polyps and CAs. Both SSA/P and SSA/P-D showed a significantly higher percentage of polyps that stained with MUC6, and a greater degree and intensity of staining for this peptide in comparison with HPs. Overall, 91% of SSA/Ps and 84% of SSA/P-Ds were positive for MUC6 in comparison with 60% of HPs (P<0.001 and P=0.02, respectively). Although polyps from both the left and right colon from each polyp group showed positivity for MUC6, a significantly higher proportion of SSA/P-Ds and traditional serrated adenomas from the right colon showed MUC6 positivity compared with those from the left. No differences were noted in MUC6 staining between each of the 3 HP subgroups. On the basis of these data, we conclude that SSA/P and SSA/P-D show increased expression of MUC6 compared with HPs; however, because of overlap in the presence, degree, and intensity of staining, use of MUC6 to differentiate HPs from SSA/P or SSA/P-D in individual cases is not reliable because of a lack of specificity. Differences in MUC6 expression between right-sided and left-sided colonic polyps supports the theory that there may be biological differences in the progression of malignancy in different portions of the colon with regard to the serrated pathway of carcinogenesis.

Intestinal differentiation in metaplastic, nongoblet columnar epithelium in the esophagus.

Barrett esophagus (BE) is defined by the presence of metaplastic esophageal columnar epithelium with goblet cells within endoscopically recognizable areas of the esophagus. However, some carcinomas in BE, or from the gastroesophageal junction region, develop within mucosa devoid of goblet cells. However, the biologic properties, pathogenesis, and risk of malignancy of metaplastic, esophageal nongoblet columnar epithelium, is, essentially, unknown. In this study, 89 patients with metaplastic esophageal columnar epithelium were evaluated immunohistochemically for markers of intestinal differentiation, such as MUC2, DAS-1, Villin, and CDX2, a marker of gastric differentiation (MUC5AC), and Ki67, a marker of cell proliferation. Of the 89 patients, 59 had columnar metaplasia with goblet cells (BE), which were further separated into low-density goblet cell and high-density goblet cell groups based on the percentage of crypts with goblet cells, and 30 patients had columnar metaplasia of the esophagus without goblet cells. As controls, gastric biopsies from 19 age and sex matched patients without esophageal or gastric pathology were used. The rate of positivity of the markers and the location of Ki67 staining was evaluated only in non-goblet columnar epithelium from all patient groups. Patients with metaplastic esophageal columnar epithelium without goblet cells showed positivity for MUC5AC, MUC2, DAS-1, Villin, and CDX2 in 100%, 0%, 30%, 17%, and 43% of cases, respectively. 17% of cases showed aberrant surface Ki67 positivity. These values were significantly higher than gastric controls, which showed absence of staining for all markers except MUC5AC (100%). In patients with metaplastic esophageal columnar epithelium with goblet cells (BE) a significant increased rate of staining was observed for all markers, except MUC5AC. In addition, both MUC2 and surface Ki67 staining were significantly increased in BE patients with high-density goblet cells versus those with low-density goblet cells. In a separate analysis in which metaplastic esophageal nongoblet epithelium was evaluated in areas of mucosa devoid of goblet cells compared with areas of mucosa with goblet cells, from patients who had goblet cells elsewhere in the mucosa (N=59), no significant differences were observed with regard to the percentage of cases that stained with any of the markers in the nongoblet epithelium in areas devoid of goblet cells, similar to the patient group with metaplastic esophageal epithelium without goblet cells (N=30). Similar to above, in all cases, expression of intestinal markers increased in areas of mucosa adjacent to goblet cells. This study provides evidence that metaplastic esophageal columnar epithelium without goblet cells shows phenotypic evidence of intestinal differentiation and supports the theory that squamous epithelium converts initially to nongoblet columnar epithelium before goblet cell metaplasia. Further prospective studies are needed to evaluate the pathogenetic sequence, natural history, and risk of malignancy of metaplastic esophageal nongoblet epithelium.

Microsatellite instability predicts improved response to adjuvant therapy with irinotecan, fluorouracil, and leucovorin in stage III colon cancer: Cancer and Leukemia Group B Protocol 89803.

PURPOSE: Colon cancers exhibiting DNA mismatch repair (MMR) defects demonstrate distinct clinical and pathologic features, including better prognosis and reduced response to fluorouracil (FU) -based chemotherapy. This prospective study investigated adjuvant chemotherapy containing FU and irinotecan in patients with MMR deficient (MMR-D) colon cancers. PATIENTS AND METHODS: Cancer and Leukemia Group B 89803 randomly assigned 1,264 patients with stage III colon cancer to postoperative weekly bolus FU/leucovorin (LV) or weekly bolus irinotecan, FU, and LV (IFL). The primary end point was overall survival; disease-free survival (DFS) was a secondary end point. Tumor expression of the MMR proteins, MLH1 and MSH2, was determined by immunohistochemistry (IHC). DNA microsatellite instability was also assessed using a panel of mono- and dinucleotide markers. Tumors with MMR defects were those demonstrating loss of MMR protein expression (MMR-D) and/or microsatellite instability high (MSI-H) genotype. RESULTS: Of 723 tumor cases examined by genotyping and IHC, 96 (13.3%) were MMR-D/MSI-H. Genotyping results were consistent with IHC in 702 cases (97.1%). IFL-treated patients with MMR-D/MSI-H tumors showed improved 5-year DFS as compared with those with mismatch repair intact tumors (0.76; 95% CI, 0.64 to 0.88 v 0.59; 95% CI, 0.53 to 0.64; P = .03). This relationship was not observed among patients treated with FU/LV. A trend toward longer DFS was observed in IFL-treated patients with MMR-D/MSI-H tumors as compared with those receiving FU/LV (0.57; 95% CI, 0.42 to 0.71 v 0.76; 95% CI, 0.64 to 0.88; P = .07; hazard ratio interaction between tumor status and treatment, 0.51; likelihood ratio P = .117). CONCLUSION: Loss of tumor MMR function may predict improved outcome in patients treated with the IFL regimen as compared with those receiving FU/LV.

p27Kip1 in stage III colon cancer: implications for outcome following adjuvant chemotherapy in cancer and leukemia group B protocol 89803.

BACKGROUND: In retrospective studies, loss of p27(Kip1) (p27), a cyclin-dependent kinase inhibitor, has been associated with poor prognosis following colorectal cancer treatment. In a prospective study, we validated this relationship in patients enrolled on a trial of adjuvant chemotherapy for stage III colon cancer. METHODS: Cancer and Leukemia Group B protocol 89803 randomized 1,264 stage III colon cancer patients to receive weekly bolus 5-fluorouracil/leucovorin or weekly bolus irinotecan, 5-fluorouracil, and leucovorin (IFL). The primary endpoint was overall survival (OS); disease-free survival was a secondary endpoint. Expression of p27 and DNA mismatch repair proteins were determined by immunohistochemistry in primary tumor and normal tissue from paraffin blocks. Data were analyzed using log-rank test. RESULTS: Of 601 tumors analyzed, 207 (34.4%) showed p27 loss, 377 (62.8%) retained p27, and 17 (2.8%) were indeterminate. Patients with p27-negative tumors showed reduced OS [5-year OS 66%: 95% confidence interval (95% CI), 0.59-0.72 versus 75%: 95% CI, 0.70-0.79; log-rank P = 0.021]. This relationship was not influenced by treatment arm. Combination of p27 status with mismatch repair status, however, identified a small subset of patients that may benefit from IFL (n = 36; 5-year disease-free survival 81%: 95% CI, 0.64-0.98 versus 47%: 95% CI, 0.21-0.72; log-rank P = 0.042; 5-year OS 81%: 95% CI, 0.64-0.98 versus 60%: 95% CI, 0.35-0.85; log-rank P = 0.128). CONCLUSIONS: Loss of p27 is associated with reduced survival in stage III colon cancer but by itself does not indicate a significant difference in outcome between patients treated IFL or 5-fluorouracil/leucovorin.

Prognostic significance of localized extra-appendiceal mucin deposition in appendiceal mucinous neoplasms.

Appendiceal mucinous neoplasms confined to the mucosa are benign, whereas those with disseminated peritoneal mucin deposits often follow an indolent, but malignant, course. Not infrequently, appendiceal mucinous neoplasms are associated with localized periappendiceal mucin deposits, but lack diffuse peritoneal involvement. Mucin deposits in these cases may be acellular or contain neoplastic epithelium (cellular mucin). Although some investigators consider both acellular and cellular periappendiceal mucin to pose no, or minimal, risk for recurrent disease, the biologic importance of localized extra-appendiceal mucin has never been evaluated. We identified 65 patients with appendiceal mucinous neoplasms, all of whom had localized periappendiceal mucin deposits without diffuse peritoneal involvement, and assessed them for the presence of extra-appendiceal epithelium and clinical outcome. Forty-nine (75%) appendices were submitted in total for histologic evaluation. Most (77%) cases showed acellular periappendiceal mucin, but 15 (23%) had scant extra-appendiceal epithelium (range: 1 to 12 cell clusters). Upon follow-up (mean: 48 mo), 2 (4%) patients with acellular periappendiceal mucin developed diffuse peritoneal disease, but neither of these appendices was submitted in total for histologic evaluation. In contrast, 5 of 15 (33%) patients with cellular periappendiceal mucin developed mucinous ascites, including 1 who eventually died of disease (P=0.03). Thus, patients with appendiceal mucinous neoplasms and acellular periappendiceal mucin are unlikely to develop recurrent disease. However, microscopic examination of the entire appendix is necessary, as lesions with extra-appendiceal tumor cells are more likely to progress to disseminated disease and result in death of the patient, even if the mucin is paucicellular and confined to the periappendiceal region.

Vascular and lymphatic properties of the superficial and deep lamina propria in Barrett esophagus.

A well-known type of mesenchymal/epithelial interaction occurs in Barrett esophagus (BE) characterized by the formation of a new, superficially located, muscularis mucosae (MM), which results in the division of the lamina propria (LP) into a superficial and deep compartment. The vascular and lymphatic properties of these 2 regions of LP are unknown. The risk of metastases of carcinomas that infiltrate these 2 anatomic areas also remains unclear. The aim of this study was to evaluate the density of blood vessels and lymphatic spaces within the superficial and deep LP and submucosa in patients with BE, and to compare the results to normal squamous-lined esophagus. Thirty esophago-gastrectomy specimens were stained immunohistochemically with CD31 (stains blood vessel and lymphatic endothelium) and D2-40 (stains lymphatic endothelium only). The density of CD31+ blood and lymphatic vessels (per 20 x field) in BE (superficial LP=37 and deep LP=38) was significantly lower compared with the LP of squamous-lined esophagus (68; P<0.001). However, the total number of blood and lymphatic vessels in the superficial and deep LP in BE was statistically similar to the LP of squamous-lined esophagus. The density of CD31+ blood and lymphatic vessels (per 20x field) in the submucosa of BE (21) was not significantly different from the submucosa of squamous-lined esophagus (23; P>0.05). We conclude that in BE, the "native" LP in squamous-lined esophagus is separated into 2 LP compartments (superficial and deep) by the formation of a new MM. These findings suggest that carcinomas that invade through the superficial MM into the deep LP should be considered "intramucosal" rather than "submucosal." Further outcome studies are needed to evaluate the risk of vascular/lymphatic metastasis in BE patients with different levels of LP invasion.

Immunoreactivity for CD25 in gastrointestinal mucosal mast cells is specific for systemic mastocytosis.

Systemic mastocytosis (SM) is characterized by the accumulation of neoplastic mast cells in bone marrow and other organs. Gastrointestinal (GI) symptoms are common in both SM and cutaneous mastocytosis [urticaria pigmentosa (UP)], and are usually caused by the release of histamine and other inflammatory mediators. Occasionally, neoplastic mast cells may also directly infiltrate the GI tract. Previous studies have suggested that enumeration of the mast cells in GI biopsies may help establish the diagnosis of SM. However, mast cells have been reported to be increased in various inflammatory diseases, and mast cell density has not been systematically evaluated in other GI disorders. Recently, expression of CD25 by mast cells in bone marrow has been shown to be specific for SM. The purpose of this study was (1) to quantitate and compare mast cells in mucosal biopsies from patients with SM involving the GI tract, UP with GI symptoms, and a control group of diverse inflammatory disorders, and (2) to determine whether immunostaining for CD25 can be used to distinguish neoplastic from reactive mast cells in GI biopsies. Seventeen GI biopsies from 6 patients with SM; 17 GI biopsies from 5 patients with UP; and 157 control cases including 10 each normal stomach, duodenum, terminal ileum, and colon, Helicobacter pylori gastritis, bile reflux gastropathy, peptic duodenitis, celiac disease, Crohn disease, ulcerative colitis, lymphocytic colitis, and collagenous colitis, 20 biopsies from 16 patients with irritable bowel syndrome, 8 biopsies from 5 patients with parasitic infections, and 9 biopsies from 7 patients with eosinophilic gastroenteritis were immunostained for mast cell tryptase, c-kit (CD117), and CD25. Mucosal mast cells were quantitated, and the presence or absence of CD25 expression on mast cells was determined. In SM patients, mast cells in the small intestine and colon numbered >100/high-power field (HPF) in nearly all cases (mean 196/HPF; range 74 to 339). This was significantly higher than in GI biopsies from UP patients (mean 17/HPF; range 8 to 32, P<0.0001) and all inflammatory diseases (P<0.01). Mast cell density in other disorders ranged from a mean of 12/HPF in H. pylori gastritis to 47/HPF in parasitic infections. Interestingly, all SM biopsies (and none of the other cases) contained aggregates or confluent sheets of mast cells. In addition, mast cells in all SM cases were positive for CD25, whereas GI mucosal mast cells in UP and all other control cases were negative. In conclusion, quantitation of mast cells can be helpful to diagnose SM in GI mucosal biopsies, although mast cells are also markedly increased in parasitic infections. Aggregates or sheets of mast cells are only seen in SM. Immunoreactivity for CD25 in GI mucosal mast cells is specific for SM and can be used to confirm the diagnosis.

A comprehensive study of nondysplastic and dysplastic serrated polyps of the vermiform appendix.

Serrated colorectal polyps often show DNA hypermethylation and/or BRAF mutations and have been implicated in the "serrated neoplastic pathway." Although similar lesions occur in the appendix, they have never been systematically investigated. We evaluated a study group of 56 serrated polyps, a control group of 17 mucinous cystadenomas, and 4 adenocarcinomas with adjacent serrated polyps of the appendix to better understand their pathogenesis. The study cases were classified as nondysplastic or dysplastic serrated polyps and evaluated for MLH-1, MSH-2, MGMT, beta-catenin, p53, and Ki-67 expression, BRAF and KRAS mutations, and microsatellite instability. Serrated polyps usually occurred in older adults with no sex predilection. Most (59%) lacked dysplasia, but all showed similar molecular features, regardless of the degree of dysplasia present. Decreased MLH-1 (50%, P<0.001) and/or MGMT (59%, P<0.001) expression and BRAF (29%, P=0.007) mutations were significantly more common in serrated polyps, but BRAF mutations were detected in a minority of the extracted DNA in 15/16 cases. Of the 28 cases with decreased MLH-1 expression, none showed high-frequency microsatellite instability. Loss of MLH-1 (25%) or MGMT (50%) expression and BRAF or KRAS mutations (50%) were inconsistently present in adenocarcinomas and were not identified in combination in any cases. We conclude that molecular features of the "serrated neoplastic pathway" are present with similar frequencies among dysplastic and nondysplastic serrated appendiceal polyps and are not highly prevalent in adjacent carcinomas. These features, including BRAF mutations, may be more closely related to a serrated morphology in appendiceal polyps rather than biologically important changes.

Primary mediastinal liposarcoma: clinicopathologic analysis of 24 cases.

Liposarcomas are rare in the mediastinum. Here, we report the clinicopathologic features of 24 cases of mediastinal liposarcoma. Patients included 13 males and 11 females, with an age range of 3 to 72 years (median 58). Nine tumors were located in the anterior mediastinum, 7 in the posterior mediastinum, 1 in the superior mediastinum, and the precise location was not specified in 7 cases. Of the anterior mediastinal tumors, 3 appeared to arise from the thymus. Tumors were well-circumscribed, multinodular masses and ranged in size from 2.2 to 61 cm in greatest dimension (median 16 cm). Histologic examination revealed that most of the cases were well-differentiated liposarcomas (10), followed by dedifferentiated liposarcomas (8), pleomorphic liposarcomas (4), and myxoid liposarcomas (2). Of the pleomorphic liposarcomas, 2 had areas that resembled myxofibrosarcoma with atypical hyperchromatic spindle cells in a myxoid stroma, but the focal presence of lipoblasts confirmed the diagnoses. Clinical follow-up was obtained in 15 cases (range 1 to 59 mo; median 26). Complete surgical excision was attempted in 13 patients; however, local recurrence was common (5 cases), including 1 patient whose tumor recurred twice. Eleven patients were alive with no evidence of disease at last follow-up (5 well-differentiated, 5 dedifferentiated, and 1 myxoid liposarcoma). Two patients developed distant metastases (dedifferentiated and pleomorphic liposarcoma). One patient was alive with disease (pleomorphic liposarcoma), and 2 died of disease (pleomorphic and dedifferentiated liposarcoma). Overall, mediastinal liposarcomas appear to be similar, in clinicopathologic terms, to liposarcomas arising in the retroperitoneum.

Immunohistochemical staining for claudin-1 can help distinguish meningiomas from histologic mimics.

The histologic distinction between meningiomas and other tumors of the central nervous system occasionally can be difficult. Claudin-1 is a tight junction-associated protein recently shown to be expressed in anaplastic meningiomas. The purpose of this study was to determine whether immunohistochemical staining for claudin-1 could help distinguish meningiomas from histologic mimics, compared with commonly used markers. Tissue sections from 10 meningothelial meningiomas, 20 fibrous meningiomas, 10 atypical meningiomas, 7 solitary fibrous tumors of the meninges, 5 meningeal hemangiopericytomas, and 7 vestibular schwannomas were stained immunohistochemically for claudin-1, epithelial membrane antigen, S-100 protein, CD34, and glial fibrillary acidic protein. In total, 21 (53%) of 40 meningiomas were immunoreactive for claudin-1, whereas none of the other tumors were positive. In contrast, there was considerable overlap in the distribution of the other antibodies evaluated. Claudin-1 seems to be a specific marker for meningiomas in this context. Although its sensitivity is relatively low, claudin-1 may be helpful in a panel of immunostains to distinguish meningiomas from histologic mimics.