Primary invasive micropapillary carcinoma of the colon

Invasive micropapillary carcinoma of the ascending colon--a report of a case

Micropapillary carcinoma (MC) has been recently recognized to be a rare but distinctive variant of adenocarcinoma. At present, only a limited number of colorectal MC cases have been reported. We present a case of MC of the ascending colon with distant metastasis. A 61-year-old female patient was hospitalized with a complaint of abdominal pain. A diagnostic work-up revealed cancer of the ascending colon with multiple lung metastases. The patient underwent a right hemicolectomy with lymph node dissection. A peritoneal nodule was observed in the abdominal cavity during surgery, and this nodule was also resected. The pathologic findings of the colon tumor revealed components of conventional tubular adenocarcinoma and micropapillary carcinoma. Lymph nodes and a peritoneal nodule revealed tubular adenocarcinoma. MC is a rare disease but has high malignant potential. In the present case the tumor was small in size, but the patient had a peritoneal and multiple lung metastases.

Clinicopathological and molecular characterization of colorectal micropapillary carcinoma

Invasive micropapillary carcinoma is associated with frequent lymph node metastasis and adverse clinical outcome. Initially described as a variant of breast and ovarian carcinoma, it has subsequently been found in other organs, most recently the colon. Reports of colorectal micropapillary carcinoma to date are limited in number, and their molecular profile has not been established. The aims of the present study were to analyze their clinicopathological features and molecular profile, and compare them with those of conventional adenocarcinoma. Clinicopathological features of a cohort of 379 patients with primary colorectal cancer were retrospectively reviewed for the presence of the pattern characteristic of micropapillary carcinoma. We also assessed the expression of KRT7, KRT20, CEACAM5, MUC1 (EMA, clone E29), MUC1 (clone MA695), MLH1, MSH2, MSH6 and TP53 by immunohistochemistry. Genetic assessments of microsatellite instability, chromosomes 17p and 18q, and mutations in TP53, BRAF and KRAS were performed using DNA extracted from formalin-fixed, paraffin-embedded sections. In all, 60 of the reviewed cases (16%) had a micropapillary component that ranged from 5 to 95% of the tumor, characterized by a higher frequency of an infiltrative pattern, lymphovascular and perineural invasion, a higher depth of invasion and more positive lymph nodes than conventional adenocarcinoma. Immunohistochemistry for MUC1 (clone MA695) and MUC1 (EMA, clone E29) enhanced the characteristic inside-out staining pattern of the micropapillary carcinoma component, whereas the rest of the tumor showed luminal staining patterns. KRT7 expression was slightly increased in micropapillary carcinoma, but did not reach significance (17-3%, P=0.1967). The molecular parameters showed a higher frequency of TP53 alterations and a low incidence of microsatellite instability and RER phenotype (loss of mismatch repair protein) in micropapillary carcinoma. With regard to the histological parameters, micropapillary carcinoma appears to be more aggressive than conventional colorectal adenocarcinoma. The molecular profile supports the hypothesis that micropapillary carcinoma carcinogenesis develops through the classical chromosomal instability pathway.

A juvenile case of pulmonary lymphangitic carcinomatosis caused by sigmoid colon cancer with a component of micropapillary carcinoma

Micropapillary carcinoma is known to be associated with a poor prognosis and high propensity for lymphovascular invasion and lymph node metastasis. Case reports on colorectal micropapillary carcinoma are relatively rare. We report here a 26-year-old woman who had sigmoid colon cancer with a micropapillary component. We made the diagnosis of pulmonary lymphangitic carcinomatosis but could not identify the primary lesion. We gave her chemotherapy as an occult primary cancer. But her respiratory condition did not improve and she died of respiratory failure. Autopsy was performed after her death. The final diagnosis was pulmonary lymphangitic carcinomatosis and multiple lymph node metastases of sigmoid colon cancer with a component of micropapillary carcinoma.

Invasive micropapillary carcinoma of the ampulla of Vater with extensive lymph node metastasis: Report of a case

Invasive micropapillary carcinoma is characterized by extensive lymph node metastasis and a poor prognosis. This histological variant was first described in breast cancer, with a few subsequent reports of it in the ampullo-pancreato-biliary region. We report a case of invasive micropapillary carcinoma of the papilla of Vater. A 53-year-old man was admitted to our hospital with signs of obstructive jaundice. Detailed investigations revealed a tumor in the periampullary region, and pancreatoduodenectomy was performed for cancer of the ampulla of Vater. Microscopic examination of the resected specimen revealed a tumor composed mainly of carcinoma cells arranged in micropapillary structures, with extensive regional lymph node metastasis. The patient had an uneventful postoperative course and was followed up in the outpatient clinic. Tumor recurrence with progressive ascites and hydronephrosis was found 8 months after surgery, and the patient died of the disease 20 months after surgery.

Micropapillary carcinoma of stomach: a clinicopathologic and immunohistochemical study of 11 cases

Micropapillary carcinoma (MPC) of the stomach is a rare, newly recognized entity, and only 2 patients with this histology have been reported. We investigated clinicopathologic features, expression of mucin (MUC2, MUC5AC, MUC6, CD10) and cytokeratin profiles (CK7 and CK20), epidermal growth factor receptors (EGFR and HER2), prognostic markers (p53 and Ki-67), and outcomes in 11 MPCs of the stomach. The proportion of MPC component ranged from 5% to 70%. Micropapillary features were often found at the deep advancing edge of the tumor. Endolymphatic tumor emboli were found in 10 cases (91%) and lymph node metastases were found in 4 cases (36%). In MPCs, positive expression was observed for Ki-67 (82%), CK7 (73%), EGFR (64%), p53 (64%), MUC5AC (45%), MUC6 (36%), and CK20 (27%). However, MUC2, CD10, and HER2 expression was negative in all cases. In 9 conventional adenocarcinomas and 11 papillary adenocarcinomas with multiple endolymphatic tumor emboli, used as control, positive expression was observed for Ki-67 (100%), CK7 (90%), EGFR (80%), CK20 (70%), p53 (70%), MUC5AC (70%), MUC6 (60%), MUC2 (40%), CD10 (25%), and HER2 (15%). Expression of MUC2, CK20, and the Ki-67 labeling index was significantly higher in control adenocarcinomas as compared with MPCs (P<0.05). However, there was no significant difference in other clinicopathologic features and overall patient survival. Subclassification of MPCs into 2 subgroups according to the proportion of micropapillary component (cut-off value was 20%) failed to find any significant clinicopathologic differences (P>0.05). Although MPCs in other organs show a poor prognosis, this does not seem to be true for gastric MPCs. Further larger studies are necessary to confirm our initial findings.

Immunohistochemical panel to identify the primary site of invasive micropapillary carcinoma

Invasive micropapillary carcinoma (IMC) is generally an aggressive morphologic variant that has been described in the bladder, lung, breast, salivary gland, gastrointestinal tract, and ovary. Given the morphologic similarities between IMCs arising from different organ systems and the high propensity of this histologic subtype for lymphatic metastasis, it may be necessary to use immunohistochemical (IHC) markers to determine the primary site of an IMC. Few studies have compared the IHC profiles of IMCs originating from different sites. We tested a panel of 11 IHC markers for their ability to distinguish urothelial, lung, breast, and ovarian IMC using a tissue microarray constructed with primary tumor tissue from 47 patients with IMC (13 bladder, 6 lung, 16 breast, and 12 ovarian). For each tumor, correct classification as IMC was verified by reverse polarity MUC1 expression. We found that immunostaining for uroplakin, CK20, TTF-1, estrogen receptor (ER), WT-1 and/or PAX8, and mammaglobin was the best panel for determining the most likely primary site of IMC. The best markers to identify urothelial IMC were uroplakin and CK20, whereas p63, high molecular weight cytokeratin, and thrombomodulin were less sensitive and specific. Lung IMC was uniformly TTF-1 positive. Breast IMC was ER positive, mammaglobin positive, and PAX8/WT-1 negative, while ovarian IMC was ER positive, mammaglobin negative, and PAX8/WT-1 positive. In the metastatic setting, or when IMC occurs without an associated in situ or conventional carcinoma component, staining for uroplakin, CK20, TTF-1, ER and WT-1, and/or PAX8, and mammaglobin is the best panel for accurately classifying the likely primary site of IMC.

KL-6 is another useful marker in assessing a micropapillary pattern in carcinomas of the breast and urinary bladder, but not the colon

To evaluate the peculiar "inside-out" pattern in micropapillary (MP) carcinoma, we investigated the usefulness of KL-6 antibody in the assessment of the MP pattern of cancers, in comparison with antibodies to epithelial membrane antigen (EMA), MUC1 (CD227), and CD 10. Immunohistochemical investigation was performed on specimens exhibiting an MP pattern obtained from 12 persons with cancer: 4 with breast carcinoma, 3 with carcinoma of the urinary bladder, and 5 with colonic carcinoma. Immunohistochemical study with KL-6, EMA, and MUC1 antibodies revealed similar continuous linear positive patterns restricted to the surface of the MP pattern in both breast and urinary bladder cancers, revealing the peculiar "inside-out" morphology. However, EMA also gave cytoplasmic positivity in most of the cases tested, and MUC1 was also present in the cytoplasm of some cases. In sharp contrast, immune reactions of colon carcinomas with these antibodies were negative, except for focal positivity for KL-6 and MUC1 antibodies in some cases. CD10 was only focally positive in an MP pattern in 4 of the 5 cases of colon carcinoma and in 1 case with carcinoma of the urinary bladder. These findings suggest that KL-6 is a useful marker to assess the MP character of breast and urinary bladder carcinomas; that MUC1 was similarly positive, with the addition of cytoplasmic positivity in some cases; and that the MP pattern of colon cancer, positive for CD 10, was different in character from both breast and urinary bladder carcinomas, although all these cancers seemingly exhibit similar MP patterns on histopathology. This heterogeneity of the MP pattern in various cancers needs to be investigated when more cases have been accumulated.

[Development of molecular-pathologic entities of colorectal cancer]

Molecular-pathologic tumor entities are characterized by a unique combination of morphological, genetic, molecular and clinical features. Increased molecular subtyping and development of diagnostics towards molecular-pathologic entities can be expected for frequent solid cancer types in the future. Initial steps towards this development are discussed for the subtypes of serrated adenocarcinoma, medullary carcinoma and micropapillary carcinoma of colorectal cancer. Based on current knowledge, medullary carcinoma of the colon is definitely a molecular-pathologic entity. A high-risk-subtype and a low-risk-subtype - but not the whole group - of colorectal serrated adenocarcinomas also fulfill the criteria of a molecular-pathologic entity. In contrast, micropapillary carcinoma shows a distinct infiltrative pattern, which can occur as part of colorectal cancer, but which is not a molecular-pathologic entity in its own right.

Immunohistochemical comparison of MUC1, CA125, and Her2Neu in invasive micropapillary carcinoma of the urinary tract and typical invasive urothelial carcinoma with retraction artifact

On the basis of recent clinical studies, some urologic oncologists do not offer bladder-sparing therapy for patients diagnosed with micropapillary carcinoma of the urinary bladder, even in the setting superficially invasive disease. Unfortunately, the distinction of invasive micropapillary carcinoma from typical invasive urothelial carcinoma with prominent retraction artifact may be difficult in some cases. In this study, we compared the immunophenotype of invasive micropapillary carcinoma to invasive urothelial carcinoma with retraction artifact using antibodies previously reported as specific for micropapillary carcinoma. Immunohistochemical staining was performed on 24 invasive micropapillary carcinomas of the urinary tract and 24 case controls of invasive urothelial carcinoma with retraction artifact using monoclonal antibodies MUC1, CA125, and Her2Neu. The staining extent and intensity for MUC1 and CA125 were scored on one representative section per case. Immunostaining for Her2Neu was scored based on the 2007 CAP/ASCO guidelines for breast carcinoma. Basal ('reverse-apical') MUC1 staining was identified in 23 of the 24 (96%) invasive micropapillary carcinomas and in 15 of the 24 (63%) invasive urothelial carcinomas with retraction artifact (P=0.0102). Membranous reactivity with CA125 was seen in 8 of the 24 (33%) invasive micropapillary carcinomas and in 3 of the 24 (13%) invasive urothelial carcinomas with retraction artifact (P=0.1681). Positive (3+) membranous Her2Neu staining was present in 6 of 24 (25%) invasive micropapillary carcinomas and in 2 of the 24 (8%) invasive urothelial carcinomas with retraction artifact (P=0.2448). The specificity for invasive micropapillary carcinoma vs invasive urothelial carcinoma with retraction artifact using antibodies MUC1, CA125, and Her2Neu was 37, 87, and 92%, respectively. Invasive micropapillary carcinoma more commonly showed immunoreactivity for MUC1, CA125, and Her2Neu compared to invasive urothelial carcinoma with retraction artifact, but only MUC1 reached statistical significance. The lack of specificity of these evaluated markers for invasive micropapillary carcinoma limits their utility in the distinction from invasive urothelial carcinoma with retraction artifact, especially given the potentially significant therapeutic implications.

Rapid progression of submucosal invasive micropapillary carcinoma of the colon in progressive systemic sclerosis: report of a case

A 71-year-old woman presented with hematochezia and narrowing of the stool. She suffered from progressive systemic sclerosis for 12 years and underwent home oxygen therapy due to pulmonary fibrosis and moderate pulmonary hypertension. Colonoscopy revealed a pedunculated, cauliflower-like polyp with a depressed surface in the sigmoid colon. The polyp was regarded as early colon cancer with possible submucosal invasion, and subsequent computed tomographic (CT) scans showed no evidence of lymph node involvement or distant metastases. Because of perioperative risks due to moderate pulmonary hypertension, she underwent an endoscopic resection of the early colon cancer. Pathological examination of the resected specimen of 20 mm diameter revealed the peculiar morphology of an adenocarcinoma with moderate lymphatic invasion. Immunohistochemical analysis for epithelial membrane antigen showed the specific 'inside-out growth pattern' indicative of invasive micropapillary carcinoma (IMPC). Taking the perioperative risks into consideration, she opted to undergo close follow-ups without an additional sigmoidectomy. At 6 months after the resection, the follow-up colonoscopy revealed a local recurrence of the colon cancer, and subsequent CT scans revealed multiple distant metastases including the lung, liver, lymph nodes and spleen. This is a rare case of a pure, submucosal IMPC of the colon. Furthermore, pure IMPC of the colon may represent a reliable predictor of lymphogenous and/or hematogenous metastases. Therefore, one should recommend an additional colectomy after endoscopic mucosal resection treatment when pathological findings confirmed IMPC of the colon and should continue a close follow-up for IMPC patients even when curative resections were performed at an early stage.

The presence of micropapillary features and retraction artifact in core needle biopsy material predicts lymph node metastasis in breast carcinoma

Retraction artifact around tumor cell nests is a characteristic feature of invasive micropapillary carcinoma (IMPC), a special type of breast cancer commonly associated with nodal metastasis. We have recently reported that the extent of retraction artifact in usual invasive ductal carcinomas (IDC) is also a strong predictor of nodal metastasis. We examined whether the presence and extent of micropapillary features and retraction artifact in core needle biopsy of breast cancers can predict nodal metastasis in a prospective series of 47 IMPC and 424 IDC. Micropapillary features were present on core needle biopsy in 28 of 47 IMPC cases. Nodal metastases were found in 21 of 28 and 14 of 19 IMPC cases with and without micropapillary features present on core needle biopsy, respectively. Lymph node metastasis was significantly associated with the presence of micropapillary features, but not with its extent within these tumors. The presence of extensive retraction artifact in core needle biopsy samples of IDC also showed a significant association with nodal metastasis. Our results indicate that the presence of micropapillary features or extensive retraction artifact on core needle biopsy of breast carcinoma can predict nodal metastasis. Our results support the notion that the characteristic clear spaces separating the tumor cells from the stroma in IMPC and IDC of the breast are not a random artifactual phenomenon simply resulting from tissue fixation and processing, but rather they are likely related to altered tumor-stromal interactions, which might have an important role in lymphatic tumor spread.

Small cluster invasion: a possible link between micropapillary pattern and lymph node metastasis in pT1 lung adenocarcinomas

Lung adenocarcinomas with micropapillary pattern (MPP) are associated with frequent nodal metastasis. However, little is known about the mechanisms that underlie MPP-associated nodal metastasis. In this study, we investigated how small micropapillary clusters of carcinoma cells present in tumoral alveolar spaces lead to increased lymph node metastasis. We analyzed 146 cases of pT1 lung adenocarcinomas with reference to the presence of MPP, small cluster invasion (SCI), and lymphatic involvement. SCI was defined as markedly resolved acinar-papillary tumor structures with single or small clusters of carcinoma cells invading stroma within fibrotic foci. The MPP-positive group (88/146 cases) was associated with significantly more frequent nodal metastasis and significantly worse survival. Moreover, SCI was significantly more frequent in the MPP-positive group (71/88 cases) than MPP-negative group (10/58 cases) and was significantly associated with lymphatic involvement (p < 0.0001) and nodal metastasis (p = 0.0073). The SCI-positive group showed significantly worse survival (5-year survival, 70%) than the SCI-negative group (91%, p = 0.0017). Carcinoma cells undergoing SCI demonstrated the same characteristic MUC-1 expression on the outer surface of cell clusters as those undergoing MPP. Thus, SCI could link MPP to nodal metastasis; carcinoma cells with MPP tend to undergo SCI in scars and invade lymphatics in pT1 lung adenocarcinomas.

Primary invasive micropapillary carcinoma of the stomach

Reported herein is the case of a 74-year-old man with an unusual gastric carcinoma that developed at the lesser curvature of the stomach. The tumor consisted of small clusters of carcinoma cells surrounded by clear spaces, with histopathology similar to invasive micropapillary carcinoma (IMPC) of the breast. The carcinoma cells, which had downregulation of E-cadherin expression, invaded the subserous tissue and metastasized to the perigastric lymph nodes. IMPC, an unusual subtype of invasive breast carcinoma, is known to have frequent lymph node metastases, resulting in a poor clinical outcome. Although IMPC has been reported in breast, urinary bladder, ureter, lung, salivary gland and colon, to the best of the authors' knowledge this is the first report of IMPC arising in the stomach. Presented here are the clinicopathological features of primary IMPC of the stomach.

Papillary adenocarcinoma arising in a duplication of the cecum

Malignant carcinomatous change is a rare complication in an enteric duplication cyst, and papillary adenocarcinoma is especially unusual. We describe a papillary adenocarcinoma, arising from a duplication of the colon, seen as a cyst with an enhancing papillary projection nodule located adjacent to the wall of the ascending colon and cecum on computed tomography.

Histopathological features and prognostic significance of the micropapillary pattern in lung adenocarcinoma

The micropapillary pattern is characterized by small papillary tufts with no fibrovascular core lying in spaces and has been reported as an aggressive variant of carcinoma in several organs. We investigated the histopathobiological properties of the micropapillary pattern with immunohistochemistry, serial sections, and electron microscopy in lung adenocarcinoma. We further analyzed its clinicopathological character and prognosis. The subjects included 383 adenocarcinoma cases, of which 184 (48%) were micropapillary pattern-positive and 199 (52%) were micropapillary pattern-negative. On histology, micropapillary tufts seemed to float in the alveolar space or spaces encased by connective tissues, whereas serial sections revealed that most tufts had continuity with other tufts and even with the main tumor. Positive staining for the adhesion molecules E-cadherin and beta-catenin suggested the preservation of tight adhesion, and electron microscopy showed the existence of intercellular junctions. Negative staining for laminin and loss of basement membrane as determined by electron microscopy suggest a loss of cell-matrix contact. Positive staining for Ki-67 indicates that cells constituting micropapillary tufts retained their proliferation potency. There were no CD34-positive cells in micropapillary tufts, and the loss of the vascular core was confirmed. In micropapillary pattern-positive cases, lymphatic invasion was identified significantly more frequently than in micropapillary pattern-negative cases (P<0.001), even at stageIA (without lymph node metastasis, N=197) (P<0.001). The 5-year and 10-year overall survival rates of the micropapillary pattern-positive stageIA group were 77.6 and 67.6%, respectively, which were significantly less than those of the micropapillary pattern-negative stageIA group (98.1 and 98.1%) (P=0.001). In conclusion, cells constituting the micropapillary pattern are likely to have acquired anchorage-independent growth and a potential for high malignancy.

Micropapillary component of urothelial carcinoma detected in transurethral resection of bladder tumor (TUR-BT) tissues: a case report

A case of urothelial carcinoma (UC) containing a micropapillary carcinoma (MPC) component in the urinary bladder of an 83-year-old man is reported. The MPC component of UC has been reported to be a variant featuring poor prognosis and rapid progression. In the present case, a characteristic MPC component with micropapillary growth, in association with a fine meshwork-like stroma, was observed in less than 10% of fragmented cancer tissues of UC, G3, obtained by transurethral resection of a bladder tumor (TUR-BT). Lymphatic invasion was also detected. UC cancer cells had invaded the prostatic glands and replaced the original epithelial cells. The unique "insideout" feature of the MPC component was immunohistochemically obvious on staining with antibody to epithelial membrane antigen (EMA). On immunohistochemical study, cancer cells of both UC and MPC components were positive for pancytokeratin AE1/AE3 and cytokeratins 7 and 20. Carcinoembryonic antigen (CEA) and CAM5.2 were only focally positive in UC cells. MIB-1(Ki-67) labeling index was high, at 80%-90%, in cancer cells of UC. This was a case of UC, G3 with invasion to the muscularis propria layer of the urinary bladder and also to the prostate. MPC and MPC components in cancers should be recognized as a marker of poor prognosis, even when detected in less than 10% of UC within TUR-BT tissues, as in the present case.

Invasive micropapillary carcinoma of the colon: an immunohistochemical study

Invasive micropapillary carcinoma has recently been reported in various anatomic sites. In this article, we report a case of micropapillary carcinoma of the sigmoid colon. A 70-year-old Japanese woman presented with bloody stool for 2 months. Detailed examination disclosed ulcerative and localized tumor in the sigmoid colon. Histological examination of the colon tumor showed a combination of conventional adenocarcinoma (60%) and micropapillary carcinoma (40%). Immunohistochemically, micropapillary carcinoma cells were positive for cytokeratin (CK) 20, carcinoembryonic antigen, and CA125, but negative for CK7, thyroid transcription factor-1, surfactant apoprotein A, estrogen receptor, and progesterone receptor. Additionally, the immunohistochemistry of epithelial membrane antigen revealed reverse polarity of neoplastic cells. Results of conventional adenocarcinoma were basically identical to those of micropapillary carcinoma. In the stroma of both conventional adenocarcinoma and micropapillary carcinoma, many myofibroblasts were present and CD34-positive stromal cells were absent. Finally, we report the fourth case of micropapillary carcinoma arising in the colon. Immunohistochemical results of CK7(-)/CK20(+) strongly suggest the colon as a primary site of micropapillary carcinoma. Additionally, micropapillary carcinoma of the colon may cause a similar stromal reaction to conventional adenocarcinoma of the colon.

Micropapillary pattern and grade of stromal invasion in pT1 adenocarcinoma of the lung: usefulness as prognostic factors

Recently, the stromal invasion grading system was proposed for small adenocarcinomas of < or =2.0 cm. The system is based on the presence or absence of a fibrotic focus, and the extent of invasion into the fibrotic focus. Although stromal invasion grading system closely correlated with the prognosis, stromal invasion grade 3, representing stromal invasion into the center of a fibrotic focus, was the largest group of tumors and showed variable prognosis. In this study, we investigated whether stromal invasion grading system could be applied to and validated in pT1 adenocarcinomas as the TNM classification is the most universally used system. Furthermore, we investigated whether stromal invasion grade 3 cases could be subclassified according to the presence and absence of micropapillary pattern. The study included 120 cases of pT1 lung adenocarcinomas, of which 81 (68%) cases were stromal invasion grade 3. Micropapillary pattern was positive in 80% of grade 3 cases. For stromal invasion grade 3 cases, the 5-year survival rate of patients with micropapillary pattern-positive carcinomas was 63%, which was significantly worse than 94% of those with micropapillary pattern-negative carcinomas (P=0.0196). The latter was very close to that for patients with stromal invasion grade 0-2 (95%). Moreover, small cluster invasion was observed at sites of stromal invasion significantly more often in micropapillary pattern-positive cases than negative cases. Thus, the stromal invasion grading system is reproducible and correlates with prognosis even in pT1 lung adenocarcinomas. Moreover, among patients with stromal invasion grade 3 carcinomas, favorable prognosis is noted in micropapillary pattern-negative cases. The micropapillary pattern subclassification provides an advantage to the stromal invasion grading system and reconfirms the importance of micropapillary pattern as a prognostic marker. Our study is the first to point to the possible association of micropapillary pattern-positive carcinomas and small cluster invasion.

The MUC13 cell surface mucin is highly expressed by human colorectal carcinomas

Mucins are complex mucosal glycoproteins that can be highly expressed by adenocarcinomas, having diagnostic, therapeutic, and biological significance. MUC13 encodes a cell surface membrane-anchored mucin expressed in the normal gastrointestinal tract, trachea, and kidney as well as colorectal, esophageal, gastric, pancreatic, and lung cancers. MUC13 protein expression was determined immunohistochemically in 99 sporadic colorectal cancers, assessing proportion of tumor cells stained, stain intensity, and localization. In normal colon, intense apical membrane and variable cytoplasmic MUC13 staining was present in both goblet and columnar cells, with strongest reactivity in the upper crypts and surface epithelium. All cancers showed staining of most tumor cells, being most conspicuous in the apical membranes of gland spaces. Left-sided tumors had a higher overall proportion of MUC13-positive tumor cells than right-sided tumors (P < .05), and high staining intensity was more frequent in adenocarcinomas (81%) than mucinous tumors (50%) (P < .05). Poorly differentiated and late-stage tumors were more likely to have high-intensity cytoplasmic staining (P < or = .025). Basolateral cell membranes were stained in 24% of cases, being more common in poorly differentiated tumors (55%) than well or moderately differentiated tumors (16%) (P < or = .001). Partial or full circumferential MUC13 staining was frequently observed in areas of tumor budding. Although MUC13 immunoreactivity was not predictive of patient outcome, there was a trend toward poorer outcome in patients with tumors showing basolateral MUC13. In summary, MUC13 was expressed abundantly by all colorectal cancers, with the highest expression in more poorly differentiated tumors.

Colorectal serrated adenocarcinoma

Colorectal cancer (CRC) ranks among the three most common cancers in terms of both cancer incidence and cancer-related deaths in most Western countries. Serrated adenocarcinoma is a recently described, distinct variant of CRC, accounting for about 7.5% of all CRCs and up to 17.5% of most proximal CRCs. It has been postulated that about 10-15% of sporadic CRCs would have their origin in serrated polyps that harbour a significant malignant potential. These lesions include hyperplastic-type aberrant crypt foci, hyperplastic polyps, sessile serrated adenomas, admixed polyps and serrated adenomas, and constitute the so-called 'serrated pathway', which is distinct from both the conventional adenoma-carcinoma pathway and the mutator pathway of hereditary non-polyposis CRC and is characterized by early involvement of oncogenic BRAF mutations, excess CpG island methylation (CIM) and subsequent low- or high-level DNA microsatellite instability (MSI). Methylation of hMLH1 is likely to explain the increased frequency of high-level MSI (16%) and methylation of MGMT is postulated to explain the low-level MSI (29%) in serrated adenocarcinomas. Reproducible histopathological criteria for serrated adenocarcinoma have recently been established and they have been qualified by DNA expression analysis for 7928 genes, showing clustering of serrated adenocarcinomas into a molecular entity apart from conventional adenocarcinoma, and representing with distinct down-regulation of EPHB2, PTCH and up-regulation of HIF1alpha.

Extensive retraction artifact correlates with lymphatic invasion and nodal metastasis and predicts poor outcome in early stage breast carcinoma

Retraction artifact resulting in clear spaces around tumor cell nests is frequently seen in histologic material and may present difficulty in their differentiation from lymphovascular invasion. We noticed that retraction artifact seemed to be more common around groups of breast cancer cells compared with benign acini, and when extensively present, metastasis to axillary lymph nodes was often seen. Thus, we performed a study of 304 cases of stage pT1 and pT2 breast carcinomas to test our hypothesis that extensive retraction artifact in tumors correlates with lymphatic spread and outcome. Tumors were evaluated to determine the presence and extent of retraction artifact around tumor cell nests and the presence of lymphatic invasion. Lymphatic invasion was confirmed by D2-40 immunostaining. The extent of retraction artifact in tumors was correlated with clinicopathologic tumor features and patient outcome. Variable degree of retraction artifact was present in 183 of 304 (60%) invasive carcinomas, with its extent ranging from 0% to 90% (median 5%). The extent of retraction artifact showed a significant correlation with tumor size, histologic type, histologic grade, presence of lymphovascular invasion, and nodal metastasis. Further, extensive retraction artifact was significantly associated with poor overall and disease-free survival in both univariate and multivariate analyses. We propose that the apparent retraction of the stroma from cells of invasive breast carcinoma on routine histologic sections is not a phenomenon merely due to inadequate fixation as currently believed. Rather, it likely signifies important biologic changes that alter tumor-stromal interactions and contribute to lymphatic spread and tumor progression.