Distinguishing benign dissecting mucin (stromal mucin pools) from invasive mucinous carcinoma

Tongue Metastasis of Mucinous Colorectal Adenocarcinoma: Report of a Rare Case

Metastases in the oral and maxillofacial region, particularly in soft tissues, are exceedingly rare. Such metastases can present as swelling in older individuals, especially in the tongue and gingiva. Furthermore, colorectal metastases at this site are commonly found in the mandible and gingiva and usually share the same morphology as the primary tumor. Herein, we report the case of a 61-year-old woman with a metastatic nodule in the tongue covered by normal mucosa. The clinical, histopathological, and immunohistochemical findings were essential for the final diagnosis of colorectal metastasis, consistent with adenocarcinoma with mucinous differentiation and intestinal phenotype. Metastases of colorectal adenocarcinoma to the tongue are rare but should be included in the differential diagnosis of nodular lesions at this site. The diagnosis can therefore be made based on meticulous clinical and histopathological examination complemented by immunohistochemistry.

Factors associated with pathological complete remission after neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a real-world clinical setting

Objective

This study aims to identify factors associated with achieving a pathological complete remission (pCR) in patients with locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT).

Methods

We conducted a cohort analysis of 171 LARC patients who underwent curative resection post-nCRT at the First Affiliated Hospital of Guangxi Medical University between January 2015 and December 2021. The data encompassed clinical and pathological information. Univariate and binary logistic regression multivariate analyses were employed to examine the factors influencing pCR achievement after nCRT. Kappa value tests were utilized to compare clinical staging after nCRT with postoperative pathological staging.

Results

Postoperative histopathology revealed that of the 171 patients, 40 (23.4%) achieved TRG 0 grade (pCR group), while 131 (76.6%) did not achieve pCR, comprising 36 TRG1, 42 TRG2, and 53 TRG3 cases. Univariate analysis indicated that younger age (p=0.008), reduced tumor occupation of intestinal circumference (p =0.008), specific pathological types (p=0.011), and lower pre-nCRT CEA levels (p=0.003) correlated with pCR attainment. Multivariate analysis identified these factors as independent predictors of pCR: younger age (OR=0.946, p=0.004), smaller tumor occupation of intestinal circumference (OR=2.809, p=0.046), non-mucinous adenocarcinoma pathological type (OR=10.405, p=0.029), and lower pre-nCRT serum CEA levels (OR=2.463, p=0.031). Clinical re-staging post-nCRT compared to postoperative pathological staging showed inconsistent MRI T staging (Kappa=0.012, p=0.718, consistency rate: 35.1%) and marginally consistent MRI N staging (Kappa=0.205, p=0.001, consistency rate: 59.6%).

Conclusion

LARC patients with younger age, presenting with smaller tumor circumferences in the intestinal lumen, lower pre-nCRT serum CEA levels, and non-mucinous adenocarcinoma are more likely to achieve pCR after nCRT. The study highlights the need for improved accuracy in clinical re-staging assessments after nCRT in LARC.

Imaging of colorectal adenomas with pseudoinvasion and malignant polyps using two-photon excitation microscopy

Introduction

Although the incidence and mortality rates of colorectal cancer exhibit significant variability, it remains one of the most prevalent cancers worldwide. Endeavors to prevent colorectal cancer development focus on detecting precursor lesions during colonoscopy. The diagnosis of endoscopically resected polyps relies on hematoxylin and eosin staining examination. For challenging cases like adenomatous polyps with epithelial misplacement, additional diagnostic methods could prove beneficial.

Methods

This paper aims to underscore stromal changes observed in malignant polyps and polyps with pseudoinvasion, leveraging two-photon excitation microscopy (TPEM), a technique extensively employed in the medical field in recent years.

Results and discussions

Both the subjective and quantitative analysis of TPEM images revealed distinct distributions and densities of collagen at the invasion front in malignant polyps compared to areas of pseudoinvasion. TPEM holds potential in discerning true invasion in malignant polyps from pseudoinvasion, offering enhanced visualization of local stromal changes.

Waist subcutaneous soft tissue metastasis of rectal mucinous adenocarcinoma: A case report

BACKGROUND

Rectal mucinous adenocarcinoma (MAC) is a rare pathological type of rectal cancer with unique pathological features and a poor prognosis. It is difficult to diagnose and treat early because of the lack of specific manifestations in some aspects of the disease. The common metastatic organs of rectal cancer are the liver and lung; however, rectal carcinoma with metastasis to subcutaneous soft tissue is a rare finding.

CASE SUMMARY

In this report, the clinical data, diagnosis and treatment process, and postoperative pathological features of a patient with left waist subcutaneous soft tissue masses were retrospectively analyzed. The patient underwent surgical treatment after admission and recovered well after surgery. The final pathological diagnosis was rectal MAC with left waist subcutaneous soft tissue metastasis.

CONCLUSION

Subcutaneous soft tissue metastasis of rectal MAC is rare, and it can suggest that the tumor is disseminated, and it can appear even earlier than the primary malignant tumor, which is occult and leads to a missed diagnosis and misdiagnosis clinically. When a subcutaneous soft tissue mass of unknown origin appears in a patient with rectal cancer, a malignant tumor should be considered.

Surgical resection identified pseudo-invasion with submucosal dense fibrosis in early colorectal cancer existing beyond the planned endoscopic submucosal dissection line: A case report

Pseudoinvasion is a phenomenon in which adenomatous tissue deviates into the submucosa with the mucosal lamina propria in colorectal epithelial tumors. A relatively large, stalked, neoplastic lesion of the sigmoid colon is considered at high risk of pseudoinvasion. A few reports have described endoscopic mucosal resection or polypectomy for colorectal tumors with pseudoinvasion, but the vertical margins were not sufficiently assessed. Because a positive margin can be a risk factor for recurrence, endoscopic treatment for pseudoinvasion should be carefully considered. We herein report a case in which even endoscopic submucosal dissection (ESD) was not adequate for curative resection of pseudoinvasion in early colorectal cancer. The endoscopic findings of a 25-mm Type 0-Is lesion in the sigmoid colon suggested a low possibility of carcinoma invasion into the deep submucosa. Although ESD was considered to be indicated in this case, laparoscopic sigmoid colon resection was eventually performed because we observed a broadly pulled muscle layer and an almost undetectable submucosal layer during ESD. The surgical specimen showed that the tumor glands of pseudoinvasion existed beyond the planned ESD dissection line, indicating that the vertical margin would have been positive if we had continued ESD. Whether pseudoinvasion was associated with the infeasibility of ESD remains unclear. This case indicates that diagnosing the presence and depth of pseudoinvasion by magnified endoscopy with narrow-band imaging is challenging and that preoperative examinations, such as endoscopic ultrasound, may be needed for a tumor with a high risk of pseudoinvasion.

In vivo detection of bile duct pre-cancer with endoscopic light scattering spectroscopy

Bile duct cancer is the second most common primary liver cancer, with most diagnoses occurring in the advanced stages. This leads to a poor survival rate, which means a technique capable of reliably detecting pre-cancer in the bile duct is urgently required. Unfortunately, radiological imaging lacks adequate accuracy for distinguishing dysplastic and benign biliary ducts, while endoscopic techniques, which can directly assess the bile duct lining, often suffer from insufficient sampling. Here, we report an endoscopic optical light scattering technique for clinical evaluation of the malignant potential of the bile duct. This technique employs an ultraminiature spatial gating fiber optic probe compatible with cholangioscopes and endoscopic retrograde cholangiopancreatography (ERCP) catheters. The probe allowed us to investigate the internal cellular composition of the bile duct epithelium with light scattering spectroscopy (LSS) and phenotypic properties of the underlying connective tissue with diffuse reflectance spectroscopy (DRS). In a pilot in vivo double-blind prospective study involving 29 patients undergoing routine ERCP procedures, the technique detected malignant transformation with 97% accuracy, showing that biliary duct pre-cancer can be reliably identified in vivo non-invasively.

[Colloid Carcinoma of the pancreas and synchronous gastrointestinal stromal tumour of stomach. A case report and review of the literature]

Colloid carcinoma (CC) is a rare histological type of adenocarcinoma of the pancreatic duct and is characterized by the presence of large lakes of extracellular mucin containing neoplastic cells. Its 5 year prognosis is more favourable than that of ductal, tubular or not otherwise specified (NOS) adenocarcinomas. We present the case of a 74-year-old woman with a thin walled, multicystic lesion in the tail of the pancreas, radiologically suggestive of a serous cystadenoma as opposed to a mucinous neoplasm. Surgery revealed a 10 x 6 cm lesion invading the splenic hilum and transverse mesocolon. Two nodes on the wall of the gastric fundus were also removed. Histopathology showed the pancreatic tumour to be a colloid carcinoma with a synchronous gastrointestinal stromal tumour of the gastric fundus.

Mucin Neovascularization as a Diagnostic Aid to Distinguish Mucinous Carcinomas From Mucocele-like Lesions in Breast Core Needle Biopsies

The distinction between mucinous carcinomas (MCs) and mucocele-like lesions (MLLs), particularly those containing detached epithelial fragments, can be problematic in the limited samples afforded by breast core needle biopsies (CNBs). Neovascularization of mucin has been proposed as a criterion to distinguish MC from MLL, but its value in helping to categorize mucin-producing breast lesions in CNB has not been previously investigated. To address this, we evaluated mucin neovascularization on hematoxylin and eosin (H&E)-stained sections of 140 CNB containing mucin-producing breast lesions including 52 MC, 17 mucin-producing ductal carcinoma in situ (mDCIS), and 71 MLL. In 116 cases with sufficient remaining material (42 MC, 16 mDCIS, and 58 MLL), we also assessed mucin neovascularization on CD31 immunostains. On H&E-stained sections, neovascularization of mucin, defined as delicate, thin-walled microvessels in mucin, and unassociated with fibrous septae, was identified significantly more frequently in MC than in MLL (69.2% vs. 14.1%; P=0.0001). The difference in the frequency of mucin neovascularization between MC and MLL was even greater on CD31 immunostains (97.6% vs. 13.8%, P<0.00001). The sensitivity, specificity, positive predictive value, and negative predictive value of mucin neovascularization for categorizing a lesion as MC were 69.2%, 85.8%, 78.3%, and 79.2%, respectively, for H&E-stained sections and 97.6%, 86.2%, 83.7%, and 98.0%, respectively, for CD31 immunostains. We conclude that mucin neovascularization is significantly more common in MC than in MLL in breast CNB on H&E-stained sections and particularly on CD31 immunostains and may be a valuable adjunct in distinguishing between MC and MLL in problematic cases.

Colorectal epithelial neoplasm associated with gut-associated lymphoid tissue

BACKGROUND

Colorectal epithelial neoplasm extending into the submucosal gut-associated lymphoid tissue (GALT) can cause difficulties in the differential diagnosis. Regarding GALT-associated epithelial neoplasms, a few studies favor the term "GALT carcinoma" while other studies have mentioned the term "GALT-associated pseudoinvasion/epithelial misplacement (PEM)".

METHODS

The clinicopathologic characteristics of 11 cases of colorectal epithelial neoplasm associated with submucosal GALT diagnosed via endoscopic submucosal dissection were studied.

RESULTS

Eight cases (72.7%) were in males. The median age was 59 years, and age ranged from 53 to 73. All cases had a submucosal tumor component more compatible with GALT-associated PEM. Eight cases (72.7%) were located in the right colon. Ten cases (90.9%) had a non-protruding endoscopic appearance. Nine cases (81.8%) showed continuity between the submucosal and surface adenomatous components. Nine cases showed (81.8%) focal defects or discontinuation of the muscularis mucosae adjacent to the submucosal GALT. No case showed hemosiderin deposits in the submucosa or desmoplastic reaction. No case showed single tumor cells or small clusters of tumor cells in the submucosal GALT. Seven cases (63.6%) showed goblet cells in the submucosa. No cases showed oncocytic columnar cells lining submucosal glands.

CONCLUSIONS

Our experience suggests that pathologists should be aware of the differential diagnosis of GALT-associated submucosal extension by colorectal adenomatous neoplasm. Further studies are needed to validate classification of GALT-associated epithelial neoplasms.

Overexpression of α1 chain of type XI collagen (COL11A1) aids in the diagnosis of invasive carcinoma in endoscopically removed malignant colorectal polyps

INTRODUCTION

The histologic distinction between benign misplaced adenomatous mucosa and invasive adenocarcinoma in colorectal polyps can be challenging. The α1 chain of type XI collagen (COL11A1) has been shown to be overexpressed in cancer-associated stromal fibroblasts. The aim of this study was to investigate the operating characteristics of COL11A1 immunostaining in benign and malignant colorectal polyps as a potential diagnostic aid.

MATERIALS AND METHODS

Sixty-six endoscopically-removed paraffin-embedded colorectal polyps were stained with anti-COL11A1 antibody. They comprised 50 malignant polyps (MPs) with invasive adenocarcinoma (including 5 with concurrent benign misplaced adenomatous mucosa) and 16 adenomas, 11 with and 5 without benign misplaced adenomatous mucosa.

RESULTS

COL11A1 was expressed either diffusely or focally in cancer-associated desmoplastic fibroblasts in 72.0% (36/50) of MPs. The rates of COL11A1 expression and the immunohistochemical staining patterns of the COL11A1 were positively correlated with the depth of cancer invasion in MPs. COL11A1 was expressed in all 9 (100%) MPs with a mucinous component and in 16/18 (88.9%) MPs associated with significant electrocautery effects. COL11A1 was not expressed adjacent to conventional adenomas or in the stroma adjacent to misplaced adenomatous mucosa.

CONCLUSIONS

COL11A1 antibody can assist in distinguishing the cancer-associated desmoplastic stroma from that associated with misplaced adenomatous mucosa. It is particularly helpful when electrocautery artifacts or mucin pools interfere with the diagnosis of invasive carcinoma. However, COL11A1 has limited value in diagnosing superfically invasive carcinomas with very little desmoplastic stroma due to its low positive rate and focal expression in some cases.

Invasive mucinous carcinoma arising in ectopic axillary breast tissue: a case report and literature review

BACKGROUND

Invasive mucinous carcinoma arising in ectopic axillary breast tissue is an uncommon diagnosis. While some published medical literature makes recommendations regarding the management of ectopic primaries, many of these recommendations are outdated. We therefore hope to provide general guidance with the management of this rare entity.

CASE REPORT

We report a case of a 70-year-old woman with primary invasive mucinous carcinoma of ectopic breast tissue. A literature study was performed on primary ectopic breast carcinoma. This case report with review of the literature was performed to provide rationales for a more conservative treatment based upon current data and treatment paradigms. Although the diagnosis of primary ectopic breast carcinoma is uncommon, the presence of a suspicious nodule along the mammary ridge should alert the clinician to consider the possibility of this diagnosis. A mammogram and ultrasound of the nodule were performed and the suspicious nodule was biopsied, confirming the diagnosis. Breast conservation was performed with standard nodal evaluation.

CONCLUSIONS

The management of primary ectopic breast carcinoma should be based upon current breast conservation techniques of orthotopic breast cancer. Current data suggest that standard treatment paradigms remain applicable to this rare clinical entity.

Characterization of dextran sodium sulfate-induced inflammation and colonic tumorigenesis in Smad3(-/-) mice with dysregulated TGFβ

There are few mouse models that adequately mimic large bowel cancer in humans or the gastrointestinal inflammation which frequently precedes it. Dextran sodium sulphate (DSS)-induces colitis in many animal models and has been used in combination with the carcinogen azoxymethane (AOM) to induce cancer in mice. Smad3^−/− mice are deficient in the transforming growth factor beta (TGFβ) signaling molecule, SMAD3, resulting in dysregulation of the cellular pathway most commonly affected in human colorectal cancer, and develop inflammation-associated colon cancer. Previous studies have shown a requirement for a bacterial trigger for the colitis and colon cancer phenotype in Smad3^−/− mice. Studies presented here in Smad3^−/− mice detail disease induction with DSS, without the use of AOM, and show a) Smad3^−/− mice develop a spectrum of lesions ranging from acute and chronic colitis, crypt herniation, repair, dysplasia, adenomatous polyps, disseminated peritoneal adenomucinosis, adenocarcinoma, mucinous adenocarcinoma (MAC) and squamous metaplasia; b) the colon lesions have variable galactin-3 (Mac2) staining c) increased DSS concentration and duration of exposure leads to increased severity of colonic lesions; d) heterozygosity of SMAD3 does not confer increased susceptibility to DSS-induced disease and e) disease is partially controlled by the presence of T and B cells as Smad3^−/−Rag2^−/− double knock out (DKO) mice develop a more severe disease phenotype. DSS-induced disease in Smad3^−/− mice may be a useful animal model to study not only inflammation-driven MAC but other human diseases such as colitis cystica profunda (CCP) and pseudomyxomatous peritonei (PMP).

Precursor lesions of mucinous carcinoma of the breast: analysis of 130 cases

Mucinous mammary carcinoma (MC) is a tumor type with relatively favorable prognosis. Unlike the circumstances surrounding conventional invasive duct carcinoma, data are limited regarding precursor lesions for MC. This study characterizes patterns of mucinous ductal carcinoma in situ (DCIS) as a precursor lesion for MC. All slides from 130 cases of MC encountered between 2000 and 2011 at Henry Ford Hospital, Detroit, MI were reviewed to subclassify MC, identify DCIS, and explore transition patterns from DCIS to MC. Calponin, p63, chromogranin, synaptophysin, CD56, and MIB-1 immunostaining analyses were performed in 65 cases. Among 106 cases of pure (71 type A, 35 type B) and 24 cases of mixed MC, DCIS appeared in 88 (68%) specimens, with all but 4 showing luminal mucin accumulation. Dominant patterns of mucinous DCIS were cribriform/solid (66), cribriform and papillary (7), papillary (5), micropapillary (3), and flat (3). Fifty-seven (68%) cases of mucinous DCIS demonstrated transitions from DCIS to MC. Luminal mucinous distention, focal flattening and attenuation of the epithelium, and disruption of the duct wall resulting in a mucocele-like extravasation of malignant epithelia with escaping mucin was a transition pattern seen with all architectures of DCIS and in all types of MC. This was the only pattern of transition to type A MC. The epithelial outpouching, formation of a cleft with accumulation of mucin around the epithelium, and transition into mucin pools with floating tumor cell clusters was the second transition pattern that went from cribriform/solid DCIS to type B and mixed MC. DCIS preceding aggressive phenotypes of MC (type B and mixed) more often had a cribriform/solid architecture, higher nuclear grade, and higher Ki-67-labeling index (all P<0.05). In summary, mucinous DCIS is a precursor to MC with distinctive features that link patterns of DCIS with aggressive MC phenotypes. The 2 observed transitions between mucinous DCIS and MC suggest that pathogenesis of different types of MC is different correlating with less or more aggressive behavior of the latter.

Focal extravasated mucin in breast core needle biopsies: is surgical excision always necessary?

Focal extravasated mucin (EM) with benign or atypical epithelium is a rare finding at breast core needle biopsy (CNB) and usually prompts surgical excision to rule out mucin-producing carcinoma. In the largest detailed series to date, we assessed surgical outcomes in lesions yielding EM with atypical or nonatypical epithelium at CNB. With IRB approval, we retrospectively reviewed 28 consecutive atypical and nonatypical CNBs with EM that underwent surgical excision at our center over a 22-year period. CNB imaging and pathologic findings were concordant if pathology sufficiently explained the radiologic features of the lesions. Pathologic findings in CNB and excision specimens were correlated. Statistical analysis was performed. CNBs sampled mammographic calcifications in 25/28 (89%) women and a mass in 3/28 (11%). All cases had concordant pathologic and imaging findings. At CNB, the epithelium associated with EM was atypical in 18/28 (64%) lesions and nonatypical in 10 (36%). Cancer (one mucinous carcinoma; three ductal carcinoma in situ) was present in 4/28 excision specimens (14%; 95% confidence intervals [CI], 4%-33%). All carcinomas were in lesions with epithelial atypia at CNB (4/18; 22%; 95% CI, 6%-48%) versus none (0/10; 0%; 95% CI, 0%-31%) in nonatypical lesions at CNB; this difference was not statistically significant (p = 0.3). Surgery is warranted for lesions yielding EM with atypia at CNB due to the high (22%) prevalence of cancer. Our data suggest that surgical excision of lesions yielding EM without epithelial atypia at CNB may not be necessary provided that imaging and pathologic findings are concordant.

Estrogen switches pure mucinous breast cancer to invasive lobular carcinoma with mucinous features

Mucinous breast cancer (MBC) is mainly a disease of postmenopausal women. Pure MBC is rare and augurs a good prognosis. In contrast, MBC mixed with other histological subtypes of invasive disease loses the more favorable prognosis. Because of the relative rarity of pure MBC, little is known about its cell and tumor biology and relationship to invasive disease of other subtypes. We have now developed a human breast cancer cell line called BCK4, in which we can control the behavior of MBC. BCK4 cells were derived from a patient whose poorly differentiated primary tumor was treated with chemotherapy, radiation and tamoxifen. Malignant cells from a recurrent pleural effusion were xenografted in mammary glands of a nude mouse. Cells from the solid tumor xenograft were propagated in culture to generate the BCK4 cell line. Multiple marker and chromosome analyses demonstrate that BCK4 cells are human, near diploid and luminal, expressing functional estrogen, androgen, and progesterone receptors. When xenografted back into immunocompromised cycling mice, BCK4 cells grow into small pure MBC. However, if mice are supplemented with continuous estradiol, tumors switch to invasive lobular carcinoma (ILC) with mucinous features (mixed MBC), and growth is markedly accelerated. Tamoxifen prevents the expansion of this more invasive component. The unexpected ability of estrogens to convert pure MBC into mixed MBC with ILC may explain the rarity of the pure disease in premenopausal women. These studies show that MBC can be derived from lobular precursors and that BCK4 cells are new, unique models to study the phenotypic plasticity, hormonal regulation, optimal therapeutic interventions, and metastatic patterns of MBC.

TNM staging of colorectal carcinoma: issues and caveats

The TNM staging system of the American Joint Committee on Cancer and the Union for International Cancer Control provides the most reliable guidelines for the prognostication and treatment of colorectal carcinoma. However, issues and caveats exist in the application of this system, mostly relating to the definition of the staging parameters and the pathologic interpretation of the gross and microscopic findings of the resected specimens. This article highlights some of the major issues in both areas. First, it assesses the definition of selected staging parameters, including pTis, pT4a versus pT4b, tumor deposits/N1c, ypT/ypN, and the TNM for rectal versus anal carcinoma. Second, it discusses major problematic areas in the pathologic interpretation of "pseudoinvasion" versus true invasion, deep pT2 versus superficial pT3, serosal involvement, radial margin, total mesorectal excision specimens, and postneoadjuvant chemoradiation rectal resections. The article also provides a brief discussion about some of the major adjunct histopathologic prognostic factors, such as medullary-type histology and tumor differentiation.

A comparative study of intraductal papillary neoplasia of the biliary tract and pancreas

Intraductal papillary mucinous neoplasm of the pancreas is a rare but well-established entity in contrast to intraductal papillary mucinous neoplasm of the biliary tract. The aim of this study was to compare the clinicopathologic features of intraductal papillary mucinous neoplasms of the biliary tract and of the pancreas. Twenty patients who underwent resection for intraductal papillary mucinous neoplasm of the biliary tract were compared with 29 cases resected for intraductal papillary mucinous neoplasm of the pancreas. Clinicopathologic characteristics and resection specimens of all patients were reassessed and immunohistochemically screened for expression of a distinct set of tumor markers. Median ages of patients with intraductal papillary mucinous neoplasms of the biliary tract and of the pancreas were 66 and 62 years, respectively (P < .05). Twelve patients with intraductal papillary mucinous neoplasm of the biliary tract (60%) had neoplasms with infiltrating carcinoma, compared with 6 patients with intraductal papillary mucinous neoplasm of the pancreas (21%, P < .05). Cytokeratin 7 and 20 expressions were equal in biliary and pancreatic intraductal papillary mucinous neoplasms. Cytokeratin 20 expression was mainly found in intestinal-type tumors. Gastric, pancreaticobiliary, and oncocytic subtypes were all observed in the intraductal papillary mucinous neoplasm of the biliary tract group. The distribution was significantly different from the intraductal papillary mucinous neoplasm of the pancreas group. The 3-year overall survival rate of malignant biliary and pancreatic intraductal papillary mucinous neoplasm was 63% and 65%, respectively (P = .798). Positive lymph nodes and a high expression of membranous mucin were associated with a significantly shorter overall survival in patients with malignant intraductal papillary mucinous neoplasm. Finally, p53 and Ki67 proliferation index were both associated with the carcinogenesis of intraductal papillary mucinous neoplasm, whereas DPC4 and CDX2 were not. Clinicopathologic features of intraductal papillary mucinous neoplasm of the biliary tract largely resemble those of intraductal papillary mucinous neoplasm of the pancreas, although intraductal papillary mucinous neoplasm of the biliary tract was associated with a higher malignancy rate at the time of surgical treatment. The level of membranous mucin expression and positive lymph nodes are significant prognosticators in patients with malignant intraductal papillary mucinous neoplasm.

Epithelial neoplasms of the appendix

CONTEXT

The appendix gives rise to an array of epithelial neoplasms showing glandular or neuroendocrine differentiation, and some tumors with elements of both cell types. Although some appendiceal neoplasms resemble their counterparts in the small and large intestines (conventional adenocarcinoma and carcinoid tumor), the appendix also gives rise to relatively unique entities including mucinous neoplasms and goblet cell carcinoid tumors, which present a challenge in pathologic classification and clinical management.

OBJECTIVE

To review clinical and diagnostic issues for 3 pathologic types of epithelial neoplasms of the appendix: (1) adenocarcinoma, with specific focus on mucinous neoplasm; (2) goblet cell carcinoid tumor and associated adenocarcinoma; and (3) typical carcinoid tumor.

DATA SOURCES

Case-derived material and literature review.

CONCLUSIONS

The most important issue in pathologic assessment of epithelial tumors of the appendix is to understand the clinical implications inherent in the diagnosis.

Mucinous adenocarcinoma showing different clinicopathological and molecular characteristics in relation to different colorectal cancer subgroups

BACKGROUND

Mucinous adenocarcinoma (MAC) is frequently reported to be associated with patients of young-age sporadic colorectal cancer (YSCC) and hereditary nonpolyposis colorectal cancer (HNPCC). This study is aimed to investigate whether the clinicopathological characteristics of MAC of HNPCC patients are distinct from those of YSCC patients.

PATIENTS AND METHODS

Eighty-two HNPCC and 68 YSCC patients recorded in the colorectal cancer registry of Chang Gung Memorial Hospital at Linkou, Taiwan, between January 1, 1995 and December 31, 2001 were included in this study. Clinicopathological and molecular variables of MAC and non-MAC of HNPCC and YSCC patients were compared accordingly.

RESULTS

Compared to non-MAC, MAC significantly showed higher frequencies of poor differentiation (32% vs. 8.2%, p = 0.001), advanced tumor stage (76% vs. 47%, p = 0.002), loss of mismatch repair protein (MMR) expression (74% vs. 44%, p = 0.023), and increased MUC2 expression (98% vs. 61%, p < 0.001). MAC of HNPCC patients showed predominant right-sided colon involvement, whereas MAC of YSCC patients displayed predominance in the left colon (79% vs. 22%, p = 0.001). Among the non-MAC counterparts, more differences were detectable including tumor stage, loss of MMR expression, and increased MUC1 expression. Furthermore, both MAC and non-MAC of YSCC patients showed higher frequencies of advanced tumor stage (81% vs. 62%, p = 0.072). In contrast, the incidence of loss of MMR expression in MAC and non-MAC of HNPCC patients is not significantly different (86% vs. 70%, p = 0.323).

CONCLUSIONS

Significantly different tumor localization was observed between mucinous YSCC (left colon predominance) and mucinous HNPCC (right colon predominance).

Pseudoinvasion in an adenomatous polyp of the colon mimicking invasive colon cancer

Pseudoinvasion or pseudocarcinomatous invasion in an adenomatous polyp of the colon can be unfamiliar to an endoscopist. Pseudoinvasion in an adenomatous polyp represents prolapse of the adenomatous epithelium into its stalk. In most cases its morphology does not differ from of general adenomatous polyps, but in some cases it can morphologically mimic a malignant polyp with submucosal invasion due to mass-like lesioning of its stalk. This makes it difficult for endoscopists to differentiate pseudoinvasion in an adenoma from an invasive carcinoma by conventional endoscopy; instead, endoscopic ultrasonography can provide useful information for differentiating these conditions. We report on an 82-year-old man who presented with a large pedunculated polyp with a thick stalk in the sigmoid colon, which mimicked a submucosal invasive carcinoma. The patient was diagnosed with pseudoinvasion in an adenomatous polyp after segmental resection of the sigmoid colon.