Villin, cytokeratin 7, and cytokeratin 20 expression in pulmonary adenocarcinoma with ultrastructural evidence of microvilli with rootlets

The utility of the lineage specific immunohistochemical stains SATB2, CDX2, and villin, and the mucin glycoproteins MUC2, MUC5AC, and MUC6 to distinguish pulmonary invasive mucinous adenocarcinoma from metastatic colorectal carcinoma

CONTEXT

The lungs are a common site of tumor metastasis. While morphology and immunophenotype can help differentiate primary from metastatic tumors, distinguishing pulmonary invasive mucinous adenocarcinoma (PIMA) from metastatic colorectal adenocarcinoma (CRC) may occasionally be challenging due to overlapping morphological and immunohistochemical features. Lineage-specific markers such as CDX2, TTF-1, and napsin A are helpful with pulmonary non-mucinous adenocarcinoma (PNMA), however they are non-specific and insensitive when applied to PIMA. SATB2 is a newer marker that distinguishes CRC from upper gastrointestinal and pancreaticobiliary tumors; its utility in distinguishing CRC from PIMA has not been fully elucidated.

OBJECTIVE

To evaluate the performance of lineage-specific and mucin glycoprotein immunostains in distinguishing PIMA and CRC.

DESIGN

We stained tissue microarrays comprising 34 PNMA, 31 PIMA, and 32 CRC with CK7, CK20, SATB2, CDX2, villin, TTF-1, napsin A, and gel-forming mucins MUC2, MUC5AC, and MUC6.

RESULTS

PIMA showed significant (>50% of cells) expression of SATB2 (6%), CDX2 (6%), villin (74%), TTF-1 (13%), and napsin A (23%). However, significant CK7 expression was seen in nearly all PIMA (30/31) and none of the metastatic CRC.

CONCLUSION

Our results suggest that CK7 remains one of the most useful markers for distinguishing primary PIMA from metastatic CRC. Expression of the mucin glycoproteins MUC5AC and MUC6 and lack of expression of MUC2 favored a diagnosis of PIMA, but expression of these markers was too heterogeneous to be of clinical utility. To our knowledge this is the only study comparing the immunohistochemical profile of PIMA and metastatic CRC in lung metastasectomy specimens.

CK-7 negative primary lung adenocarcinoma

Cytokeratin (CK) 7 is normally expressed in the vast majority of lung adenocarcinoma (ADC). However, on rare occasions, as reported in this paper, CK7 negativity can challenge the diagnosis of pulmonary ADC. Hence, the need to use a combination of 'immunomarkers' such as thyroid transcription factor 1, Napsin A, p40, p63 and CK20.

Mucinous Adenocarcinoma of the Colon with Clear Cell Component: A Case Report and Literature Review

Clear cell adenocarcinomas of the colon are defined as a subtype of colorectal adenocarcinoma with clear cell morphology. A 65-year old man was admitted to a Gastroenterology Department for diagnostic evaluation of a tumor in the sigmoid colon found on CT. There, the patient developed complete bowel obstruction and was operated urgently, where intraoperatively, a large tumor in the sigmoid fixated to the lateral abdominal wall was revealed. A subtotal colectomy was performed. Histopathological analysis of the surgical specimen was conducted. The immunohistochemistry staining was positive for CEA, CDX2, and CD20 and negative for CK7, CD10, MUC2, AFP, and PAS staining. Mismatch repair protein testing was negative. The pathological diagnosis was mucinous carcinoma with a clear cell component which bears an extremely low incidence that has been scarcely reported in literature. This stresses the need for more case reports like ours to be published.

Villin expression in human tumours: a tissue microarray study on 14,398 tumours

BACKGROUND

Villin is a protein of the brush border of epithelial cells which is used as an immunohistochemical marker for colorectal and gastrointestinal neoplasms. However, other tumor entities can also express villin.

METHODS

To comprehensively determine villin expression, tissue microarrays containing 14,398 samples from 118 different tumor types as well as 608 samples of 76 different normal tissues were analyzed by immunohistochemistry.

RESULTS

Villin was found in 54 of 118 tumor categories, including 36 tumor categories with strong staining. Villin expression was frequent in colorectal, upper gastrointestinal tract, pancreatobiliary, and renal tumors as well as in mucinous ovarian cancers, yolk sac tumors and in neuroendocrine neoplasms. Reduced villin expression was linked to advanced pT stage, lymph vessel invasion and microsatellite instability (p≤0.0006) in colorectal adenocarcinoma. In summary, our data demonstrate that villin expression is most common in gastrointestinal, pancreatobiliary, and neuroendocrine neoplasms, yolk sac tumors and mucinous ovarian cancers.

CONCLUSION

Our data support a high utility of villin immunohistochemistry for the identification of tumors with gastrointestinal, pancreatobiliary, and yolk sac tumor origin. However, considering that at least a weak villin positivity in some tumor cells occurred in 54 different tumor categories, villin immunohistochemistry should be applied as a part of a marker panel rather than as a stand-alone marker.

Clinicopathologic Significance of Intestinal-type Molecules' Expression and Different EGFR Gene Status in Pulmonary Adenocarcinoma

Variant pulmonary adenocarcinoma with intestinal-type molecules shares similar molecular expression with colorectal carcinoma. However, expression of such molecules and their association with survival time with clinicopathologic parameters, such as epidermal growth factor receptor (EGFR) gene status in other types of pulmonary adenocarcinoma, has been rarely demonstrated. Sixty patients with resected pulmonary adenocarcinoma were divided into the enteric differentiation group (I group, n=30) and the usual group (U group, n=30). Immunohistochemical staining was used to assess the expression of carcinoembryonic antigen (CEA), Villin, CK20, and caudal-related homeobox 2 (CDX2). EGFR gene status was examined by Fluorescence Quantitative polymerase chain reaction. Kaplan-Meier survival curve was drawn by GraphPad Prism 5.0 software. The results showed that there was a significant difference between the 2 groups (P<0.05) in the expression of Villin, CK20, and CDX2, whereas the expression of CEA showed no significant difference (P>0.05). Compared with the U group, patients in the I group were mainly female individuals and in clinical stages III to IV, prone to lymph node metastasis (P<0.05). The patients in the I group with CDX2CK20 phenotype (tumor size>5 cm) had a shorter survival time (P<0.05), and EGFR gene status was not associated with median survival time and the expression of CEA, Villin, CK20, and CDX2 (P>0.05). Thus, our research indicates that patients with enteric differentiation have unique clinical characteristics and different prognosis, which may play important roles in diagnosis and choosing therapeutic strategies for pulmonary adenocarcinoma patients in clinical practice.

Clinicopathological, radiographic, and oncogenic features of primary pulmonary enteric adenocarcinoma in comparison with invasive adenocarcinoma in resection specimens

Primary pulmonary enteric adenocarcinoma (PEAC) is a rare subtype of primary lung adenocarcinoma. However, it is not known whether there are any distinctive clinical or molecular features.PEACs were retrospectively identified in 28 patients from July 2014 to June 2016. We compared the clinicopathological, radiographic, and oncogenic characteristics of PEAC and primary pulmonary invasive adenocarcinoma (IAC).A total of 28 PEAC patients and 92 IAC patients were compared. PEAC occurred more frequently in males (P = .008), in older patients (P = .041), in those with larger lesions (P = .001), and in those in a more advanced stage (P = .011). Radiologically, PEAC patients had larger lesions (P = .025) and more solid (P = .006); however, there were no statistically significant differences in lobulation, spiculation, pleural indentation, pleural effusion, and lymphadenopathy between PEAC and IAC. PEAC had higher values of carcinoembryonic antigen (P = .008) and carbohydrate antigen 19-9 (P < .001) than IAC. PEAC had a higher incidence (40% vs 63%, P < .001) of Kristen rat sarcoma viral oncogene homolog (KRAS) mutations and a lower incidence (10.71% vs 3.3%, P < .001) of epidermal growth factor receptor (EGFR) mutations. Villin may be a useful marker in the differential diagnosis of PEAC. KRAS mutations occurred more frequently in PEACs, which are cytokeratin 7-negative (P = .032). EGFR mutation rates were higher in PEACs, which are cytokeratin 20- and caudal type homeobox transcription factor 2-negative (P = .041).PEAC is a rare and heterogeneous nonsmall-cell lung cancer subgroup with distinctive clinicopathological, radiographic, and molecular features. These results need to be further confirmed in future studies.

Clear cell adenocarcinoma of the colon: a case report and review of the literature

Clear cell adenocarcinoma of the colon has been described scarcely in the literature. It affects elderly men more commonly than women and usually appears in the left side of the colon. A Hispanic 41-year-old female came to the emergency room with abdominal pain, vomiting, and distension. Physical exam revealed generalized tenderness without peritoneal signs. Laboratory data was unremarkable. A CT scan showed an apple-core lesion in the distal colon. A flexible sigmoidoscopy revealed an obstructive mass that made further evaluation impossible. Exploratory surgery revealed a hard mass obstructing the descending colon, which was resected. Histopathology analysis with immunohistochemistry staining was positive for cytokeratin 20, cytokeratin 10, CDX2, and villin, while it was negative for cytokeratin 7, RCC, vimentin, and CD31. These results confirmed the clear cell variant of the adenocarcinoma. Clear cell adenocarcinomas usually arise from the kidneys and Müllerian organs. Immunohistochemistry is crucial for establishing the origin of these neoplastic cells. A cytokeratin 20+/7− with positive CDX2 is highly specific and sensitive for intestinal neoplastic origin. The main treatment has been surgery alone with moderately good results. More research and information about this malignancy is needed, especially in regard to prognosis and in order to provide the best treatment option.

Loss of villin immunoexpression in colorectal carcinoma is associated with poor differentiation and survival

Background and Aims. Villin is a highly specialised protein and is expressed in intestinal and renal proximal tubular epithelium. It was detected in colorectal carcinomas (CRC) and other nongastrointestinal tumours. The aim of the current study is to investigate the immunohistochemical expression of villin in a subset of primary CRC and determine its relation to tumour differentiation, invasion, nodal metastasis, recurrence, and disease-free survival. Patients and Methods. Paraffin blocks of 93 cases of CRC were retrieved constituting 93 primary CRC and 58 adjacent normal mucosa. Immunohistochemistry was performed using antivillin antibody. The extent (%) of villin immunoexpression was categorised for statistical analysis. Statistical tests were used to determine the association of villin with clinicopathological characteristics: age, sex, tumour location, tumour size, depth of invasion, tumour grade, nodal metastasis, lymphovascular invasion, margin status, recurrence, and survival. Results. Villin immunostaining results showed that villin is downregulated in CRC. Villin has no association with age, sex, tumour location, depth of invasion, nodal metastasis, lymphovascular invasion, margin status, and recurrence. However, villin is expressed in higher rate in CRC less than 5 cm, well- and moderately differentiated CRC. Poor survival was associated with tumour with low villin immunoexpression. Conclusion. Villin was downregulated in CRC. Villin immunoexpression in CRC is associated with better survival, well-differentiated tumours, and small-sized tumours. Villin has no significant association with disease recurrence or nodal metastasis. More in vivo and in vitro studies are required for further elucidation of how villin may be involved in CRC.

Pulmonary enteric adenocarcinoma with villin brush border immunoreactivity: a case report and literature review

Pulmonary enteric adenocarcinoma, a rare histologic type of primary pulmonary adenocarcinoma with only 16 cases reported to date, has to be differentiated from metastatic colorectal carcinoma. Here we report a case of pulmonary enteric adenocarcinoma which shows villin immunoreactivity in the brush border of tumor cells. As a marker for gastrointestinal adenocarcinoma, villin has been rarely found positive like this pattern in pulmonary adenocarcinomas. This case suggests brush border immunoreactivity of villin is possible in some cases of pulmonary enteric adenocarcinomas. We suggest pathological practitioners pay attention to it.

The Role of KRAS Mutational Analysis to Determine the Site of Origin of Metastatic Carcinoma to the Lung: A Case Report

Metastatic carcinomas involving the lung are a common specimen encountered in surgical pathology. These metastases may have different morphologic, and architectural patterns and may mimic primary pulmonary adenocarcinoma, especially the intra-alveolar (lepidic) pattern of spread which may simulate a primary pulmonary bronchioloalveolar carcinoma (adenocarcinoma in situ). We present the case of a metastatic pancreatic adenocarcinoma that morphologically mimicked bronchioloalveolar carcinoma of the lung in that the tumor had an exclusive intra-alveolar pattern of spread and had an immunophenotype that was noninformative as to the site of origin (cytokeratin 7+, cytokeratin 20−, TTF-1−). In this case, we used KRAS gene mutation analysis to support that the lung carcinoma represented a metastatic pancreatic carcinoma as they both possessed identical codon 12 KRAS mutations. We show that this method may be a useful way to prove site of origin of metastatic carcinoma—particularly if standard morphologic or immunohistochemical analysis is not definitive.

Bronchioloalveolar differentiation in lung adenocarcinomas

The goals of the study were to determine what percentage of neoplasms with a bronchioloalveolar (BAC) component were considered pure BAC by current World Health Organization (WHO) criteria. Next, we wanted to determine the number of mucinous BACs using histochemical staining with Alcian Blue PAS. Finally, we aimed to elucidate by immunohistochemistry the thyroid transcription factor-1 (TTF-1) frequency and cytokeratin 7 (CK7) expression, particularly in regard to the mucinous and non-mucinous subtypes of BAC tumors. We made a retrospective review of Hematoxylin and Eosin stained slides and classification of histologic grade, tumor subtype, and percentage of pure BAC pattern, with further characterization by histochemical staining for Alcian Blue PAS and Immunohistochemical staining for thyroid TTF-1 and CK7. Only 10 of 30 tumors examined could be classified as BAC by current strict WHO criteria. Nine cases were classified into non-mucinous and only one case was recognized as mucinous BAC, which showed positive staining for Alcian Blue PAS. TTF-1 positivity was in 100% of the non-mucinous BACs and complete absence of staining was in one case of mucinous BACs. CK7 expression in bronchioloalveolar carcinoma has demonstrated CK7 marked staining in 90% of non-mucinous BACs, also one case of mucinous BACs showed marked staining for TTF-1. BACs of mucinous morphology were notable for their conspicuous absence of TTF-1 immunoreactivity.

Mouse embryonic stem cells give rise to gut-like morphogenesis, including intestinal stem cells, in the embryoid body model

Embryonic stem (ES) cells have been proposed as candidates for cell replacement therapy in patients with intestinal failure because these cells can be expanded indefinitely without losing their pluripotent phenotype. We investigated the differentiation capacity of mouse ES cells into gut-like structures, including intestinal stem cells, and defined culture conditions for efficient induction of formation of these structures. ES cell-derived gut-like structures (ES-guts) were reproducibly induced in developing embryoid bodies (EBs) by day 21 of differentiation culture. ES-guts contained an endodermal epithelium, a smooth muscle layer, interstitial cells of Cajal, and enteric neurons and showed spontaneous contraction. Transplantation of ES-guts under the kidney capsules of immunodeficient mice induced formation of highly differentiated epithelium composed of absorptive cells and goblet cells in the grafts. Immunoreactivity for Musashi-1 (Msi-1), a marker of intestinal stem cells, was detected in 1.9% of the columnar epithelial cells in the graft. Culture with 0.1% dimethyl sulfoxide increased the numbers of ES-guts in EBs, and serum-replacement (SR) culture, in comparison to standard ES culture containing 15% serum, increased the area ratio of ES-guts to EBs. SR culture also promoted maturation of epithelium to form a single layer of columnar epithelial cells, including absorptive cells and goblet cells. Expression of Msi-1 mRNA and protein was significantly enhanced when EBs were cultured under SR conditions. In conclusion, SR conditions efficiently induce formation of ES-guts and promote differentiation of epithelium, including intestinal stem cells. These results suggest the feasibility of cell-based therapy for intestinal failure based on ES cell culture systems.

Immunohistochemistry of pulmonary and pleural neoplasia

CONTEXT

The use of immunohistochemical stains has several applications in the evaluation of pulmonary and pleural neoplasms. The number of available immunohistochemical stains is continually expanding and, although these stains are an important diagnostic adjunct, their use is not without limitations and pitfalls.

OBJECTIVE

To review and summarize the primary immunohistochemical applications with regard to the most common pulmonary and pleural neoplasms and discuss newly developed markers and common pitfalls.

DATA SOURCES

Pertinent peer-reviewed literature emphasizing immunohistochemical applications in common lung and pleural tumors, unusual and problematic staining patterns in frequently encountered subtypes/histologic variants, and recently developed immunohistochemical stains of potential promise.

CONCLUSIONS

Immunohistochemical stains provide the greatest aid in establishing the site of origin of adenocarcinomas encountered in the lung and in separating epithelioid mesothelioma from adenocarcinoma. Certain subtypes of pulmonary adenocarcinomas may exhibit unusual staining patterns that may be potentially problematic. Immunohistochemistry has a more limited role in separating small cell carcinoma from non-small cell carcinoma, and extreme caution must be used in the situation of crushed biopsy specimens.

Undifferentiated tumor: true identity by immunohistochemistry

CONTEXT

"Undifferentiated tumor" refers to a heterogeneous group of neoplasms with little or no evidence of differentiation on routine light microscopic morphology.

OBJECTIVE

To identify the true identity of undifferentiated tumors by immunohistochemical analysis.

DATA SOURCES

Review of the pertinent literature and the authors' experience.

CONCLUSIONS

For treatment and prognostic evaluation, it is crucial to delineate whether an undifferentiated neoplasm is epithelial, mesenchymal, melanocytic, or hematopoietic in nature. Application of a screening panel to demonstrate the expression of markers of major lineages is fundamental for determination of the broad category of neoplasia. Because poorly differentiated carcinomas and in particular sarcomatoid carcinomas are known to be heterogeneous in their antigen expression, several epithelial markers in combination may be required to establish the carcinomatous nature of tumor. A diagnostic misinterpretation as a consequence of occasional aberrant or unexpected antigen expression is best avoided by using a broad panel that includes both antibodies that are anticipated to be positive and those that are expected to be negative. In this treatise, the immunohistochemical dissection of undifferentiated tumors on the basis of their morphologic features is outlined, supplemented with algorithmic immunohistochemical analysis for each morphologic category of small round cell tumors, carcinomatous tumors, sarcomatous (or sarcoma-like) tumors, and tumors with histologically overlapping features, including hematolymphoid malignancies, melanoma, and sarcomas with epithelioid appearance. The utility of several organ- or tissue-specific markers in the context of undifferentiated tumors is reviewed.

Immunohistochemical panel of undifferentiated orbital metastatic carcinomas

PURPOSE

To examine the applicability of an immunohistochemical panel of seven monoclonal antibodies to identify the primary site of poorly differentiated orbital metastatic carcinomas.

MATERIAL AND METHODS

Immunohistochemistry was performed to detect cytokeratin (CK) 7, CK20, thyroid transcription factor-1 (TTF-1), BRST1, BRST2, carcinoembryonic antigen (CEA) and prostate-specific antigen (PSA) in seven cases of poorly differentiated orbital metastases. Of the seven cases, four were female and three male. The youngest patient was thirty-six while the oldest was eighty-eight years of age.

RESULTS

The immunohistochemical panel alone was helpful to identify the primary source of the metastatic lesion in three out of the seven cases. Two of them were metastatic breast carcinomas (BRST1, BRST2 positive) and one was a prostate carcinoma (PSA positive). By correlating the immunohistochemical results with the previous clinical history, the primary site could be identified in two more cases. In those metastatic lesions, the positive staining for CK7, CK20, and CEA, associated with negative staining for BRST1, BRST2, PSA and TTF-1, indicated bladder as the probable primary site. In two out of seven cases, the metastatic tumor was only positive for CEA, therefore a primary site could not be identified.

CONCLUSIONS

An immunohistochemical panel of poorly differentiated orbital metastases is helpful in the identification of the primary tumor site. The association of seven markers with the patient's clinical history allowed for the positive identification of the primary tumor in the majority of these cases.

Sentinel lymph node mapping and molecular staging in nonsmall cell lung carcinoma

BACKGROUND

Lymph node (LN) involvement predicts recurrence in patients who have undergone resection of apparently localized nonsmall cell lung carcinoma (NSCLC). Standard detection methods for LN disease have a low sensitivity, and many patients with apparent N0 disease status develop recurrent disease. Molecular techniques can improve the detection of micrometastases, whereas sentinel lymph node (SLN) mapping can indicate which LN may contain micrometastases. These methods, although potentially complementary, have not, to the authors' knowledge, been used together previously.

METHODS

The authors used SLN mapping and molecular staging to improve the detection of LN micrometastases in patients with NSCLC. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for cytokeratin-7 (CK7), expressed both in normal lung and in malignant lung, was used to identify tumor-derived material in LN.

RESULTS

SLN mapping was performed in 13 patients, with 1-3 SLNs identified in each patient, and sufficient RNA for RT-PCR was obtained in 12 of these 13 patients. Eleven of 12 tumors expressed CK7. Overall, 32 LNs were positive for CK7, including 13 of 21 SLNs. Ten of 11 patients with evaluable SLNs had at least 1 CK7-positive SLN. Routine pathology showed Stage I disease in eight patients, T3N0 disease in one patient, and LN-positive disease in two patients. Of the nine patients with N0 disease according to routine pathology that was evaluable by RT-PCR, eight patients were upstaged by this technique. All patients with positive LN status by routine pathology who were evaluable by RT-PCR analysis had positive RT-PCR results.

CONCLUSIONS

LN micrometastases were common in resected NSCLC, including patients with N0 disease according to routine pathology. SLN mapping was useful for identifying disease-containing LNs. This approach may be useful for stratifying histologically N0 patients into higher risk and lower risk groups.

Diagnostic utility of CDX-2 expression in separating metastatic gastrointestinal adenocarcinoma from other metastatic adenocarcinoma in fine-needle aspiration cytology using cell blocks

BACKGROUND

CDX-2 gene is a transcription factor that is involved in the proliferation and differentiation of intestinal epithelial cells. Recent studies have shown that CDX-2 could be used as an immunohistochemical marker to differentiate metastatic gastrointestinal adenocarcinoma from other metastatic adenocarcinomas in surgical pathology. The objective of the current study was to investigate the diagnostic value of CDX-2 to separate metastatic gastrointestinal adenocarcinoma from other metastatic adenocarcinomas in fine-needle aspiration cytology (FNAC).

METHODS

Sixty-two FNAC specimens of metastatic adenocarcinomas with corresponding cell blocks were retrieved from the hospital computer system. There were 22 specimens of metastatic gastrointestinal adenocarcinoma, 20 specimens of metastatic pulmonary adenocarcinoma, and 20 specimens of metastatic adenocarcinomas from other sites, including 10 from the breast, 3 from the ovaries, 4 from the pancreas, and 3 from the prostate. Radiology and histologic evaluation confirmed all cases. Sections were immunostained for CDX-2 and thyroid transcription factor-1 (TTF-1) using a heat-induced epitope retrieval technique.

RESULTS

In metastatic gastrointestinal adenocarcinoma, CDX-2 demonstrated positive nuclear staining in 19 of 22 specimens (86%). Other specimens of metastatic adenocarcinoma were negative for CDX-2. TTF-1 expression was detected in 0%, 80%, and 0% of metastatic gastrointestinal adenocarcinoma, pulmonary adenocarcinoma, and other adenocarcinoma specimens, respectively.

CONCLUSIONS

The results of the current study demonstrated that CDX-2 is a sensitive and a specific marker to separate metastatic gastrointestinal adenocarcinoma from other metastatic adenocarcinomas in FNAC specimens.

Immunohistochemical analysis of lung carcinomas with pure or partial bronchioloalveolar differentiation

CONTEXT

In 1999, the World Health Organization redefined bronchioloalveolar carcinomas (BACs) as those neoplasms with only a pure lepidic growth pattern and no invasion.

OBJECTIVES

The present study examined 45 lung cancers with a BAC component (1) to determine whether these tumors would be classified as BACs by current World Health Organization standards, (2) to quantitate the BAC component within these tumors, and (3) to see if phenotypic differences exist between the so-called invasive and noninvasive regions of these tumors.

DESIGN

Retrospective review of hematoxylin-eosin-stained slides and classification of histologic grade, tumor subtype, and percentage of pure BAC pattern, with further characterization by immunohistochemical staining for thyroid transcription factor 1, cytokeratin 7, cytokeratin 20, and Ki-67 antibodies.

RESULTS

Only 7 (15.6%) of the 45 tumors examined could be classified as BAC by current strict World Health Organization criteria. Those tumors, classified as nonmucinous and mixed, showed similar immunohistochemical staining for cytokeratin 7, cytokeratin 20, and thyroid transcription factor 1; mucinous tumors showed disparate staining. Significant differences in immunohistochemical staining and tumor cell proliferation were seen for the regions of tumors designated as lepidic, infiltrative, and leading edge and for the regions of tumors with different histologic grades (ie, well, moderately, and poorly differentiated).

CONCLUSIONS

Nonmucinous and mixed BACs are phenotypically similar and show identical immunohistochemical staining patterns; mucinous tumors, on the other hand, show disparate immunohistochemical staining. Pulmonary neoplasms designated as adenocarcinomas with a BAC component represent a heterogenous group with a range of cell types, differentiation, growth, and immunophenotypes. Within an individual neoplasm, there are regional differences in these parameters as well.

CDX-2 homeobox gene expression is a reliable marker of colorectal adenocarcinoma metastases to the lungs

Lung metastases from colorectal carcinomas (CRC) can be resected with improved survival. The distinction between primary lung adenocarcinomas and metastases from CRC may sometimes be difficult, especially on cytologic specimens or small bronchoscopic biopsies. Immunohistochemistry may be of help in this setting: available markers include TTF-1 and SP-A, which are markers of lung origin, whereas there are no good markers of intestinal origin, besides cytokeratin 7 and 20 coexpression pattern, which is not very specific. The nuclear CDX-2 transcription factor, which is the product of a homeobox gene necessary for intestinal organogenesis, is expressed in normal colonic epithelia and most colorectal adenocarcinomas, and could potentially be of diagnostic usefulness. Our aim was to investigate CDX-2 immunohistochemical expression using a new monoclonal antibody and to verify if CDX-2 can be a reliable marker to identify the colorectal origin of lung metastases. CDX-2 expression was evaluated in formalin-fixed, paraffin-embedded samples of normal adult human tissues (50 samples) and in 299 surgically resected carcinomas of different origins, including 125 non-lung adenocarcinomas, 117 primary lung tumors, 5 mesotheliomas, and 52 adenocarcinomas metastatic to the lung. CDX-2 was also evaluated on a series of 20 bioptic and 10 cytologic specimens (5 cases of colorectal metastases to the lung, 5 cases of metastases from other organs, and 10 primary lung adenocarcinomas). In normal tissues CDX-2 immunoreactivity was observed only in ileal and colorectal epithelia. CDX-2 was expressed in almost all primary and metastatic CRC (88 of 90) and was never observed in primary lung tumors. CDX-2 was also expressed in a limited group of adenocarcinomas of other sites (gastric, biliopancreatic, and mucinous ovarian adenocarcinomas). CDX-2 could be easily detected in all bioptic and cytologic samples of CRC metastases. CDX-2 is a reliable, specific, and sensitive immunohistochemical marker of normal and neoplastic intestinal epithelium. CDX-2 can be easily applied to routine histologic and cytologic material and is therefore a useful marker in the differential diagnosis of primary versus metastatic adenocarcinomas in the lung, and among metastases from an unknown primary, supports intestinal origin.

Expression of cytokeratin 20 in mucinous bronchioloalveolar carcinoma

Mucinous bronchioloalveolar carcinomas (BACs) can closely mimic metastatic adenocarcinoma to the lung both clinically and morphologically. Several studies have demonstrated that the differential expression of cytokeratin 7 (CK7) and cytokeratin 20 (CK20) is a valuable diagnostic tool in differentiating primary pulmonary adenocarcinomas (PPAs) (usually CK7 positive/CK20 negative) from metastatic colonic adenocarcinoma (usually CK7 negative/CK20 positive). The present study is designed to correlate the histologic subtypes of PPA with expression of 7 and 20. A total of 113 cases of bonafide PPA were selected and classified according to the 1999 World Health Organization criteria as adenocarcinoma, NOS (n = 80), nonmucinous BAC (n = 14), and mucinous BAC (n = 19). Representive sections of all the tumors were immunohistochemically analyzed for CK7 and CK20 expression. To evaluate the diagnostic utility of CK7 and CK20 expression, 6 cases of colonic adenocarcinoma metastatic to the lung were tested with the same antibodies and compared with mucinous BAC. Results were expressed in a semiquantitative fashion based on the percentage of positive tumor cells: <10%, focal; 10% to 25%, 1+; 26% to 75%, 2+; > or =76%, 3+. All 113 PPAs exhibited strong, diffuse CK7 expression. With respect to CK20 expression, 17 of the 19 cases (89.4%) of mucinous BAC showed moderate to strong expression of this protein, whereas only 10 cases of conventional adenocarcinomas and 4 cases of nonmucinous BAC exhibited expression. All 6 examples of metastatic colonic adenocarcinomas were negative for CK7 and strongly positive for CK20. In summary, mucinous BAC is distinct from other PPAs by virtue of its CK20 expression. Although the CK7/CK20 immunoprofile is a valuable diagnostic marker for differentiating primary lung adenocarcinoma from metastatic colonic adenocarcinoma, caution should be exercised when dealing with mucinous BAC.

Cytokeratin 7 and 20 staining for the diagnosis of lung and colorectal adenocarcinoma

The origin of metastatic adenocarcinoma lesions can sometimes be difficult to diagnose. The objectives of our study were to establish the cytokeratin staining pattern of primary and metastatic lung and colorectal adenocarcinomas, and to determine if this helps to identify the site of origin of metastatic lesions. We reviewed a total of 102 tissue samples from patients in our tumour registry, with either primary or metastatic lung or colorectal adenocarcinoma. Tissue sections were stained for cytokeratin 7 and 20 and read as positive or negative for staining. Clinical and radiologic information was reviewed from computerised charts. The cytokeratin 7+/cytokeratin 20- pattern characterised 96% (29 out of 30) of primary and 95% (21 out of 22) of metastatic lung adenocarcinomas. All the primary (26), and 88% (21 out of 24) of metastatic colorectal adenocarcinomas stained cytokeratin 7-/cytokeratin 20+. Samples from a variety of metastatic sites were evaluated for cytokeratin 7 and 20 staining. Out of the 102 samples, in 95% (97 out of 102) of the cases, the cytokeratin 7 and cytokeratin 20 staining pattern characterised and differentiated between lung and colorectal adenocarcinoma. Primary and metastatic lung adenocarcinomas show a cytokeratin 7+/cytokeratin 20- staining pattern, while colorectal adenocarcinomas stain cytokeratin 7-/cytokeratin 20+. Cytokeratin staining is helpful in the diagnostic differentiation of metastatic lesions from these two common primaries, and assists in determining the site of origin of metastatic lesions.

Cytokeratin 7 and 20 staining for the diagnosis of lung and colorectal adenocarcinoma

The origin of metastatic adenocarcinoma lesions can sometimes be difficult to diagnose. The objectives of our study were to establish the cytokeratin staining pattern of primary and metastatic lung and colorectal adenocarcinomas, and to determine if this helps to identify the site of origin of metastatic lesions. We reviewed a total of 102 tissue samples from patients in our tumour registry, with either primary or metastatic lung or colorectal adenocarcinoma. Tissue sections were stained for cytokeratin 7 and 20 and read as positive or negative for staining. Clinical and radiologic information was reviewed from computerised charts. The cytokeratin 7+/cytokeratin 20- pattern characterised 96% (29 out of 30) of primary and 95% (21 out of 22) of metastatic lung adenocarcinomas. All the primary (26), and 88% (21 out of 24) of metastatic colorectal adenocarcinomas stained cytokeratin 7-/cytokeratin 20+. Samples from a variety of metastatic sites were evaluated for cytokeratin 7 and 20 staining. Out of the 102 samples, in 95% (97 out of 102) of the cases, the cytokeratin 7 and cytokeratin 20 staining pattern characterised and differentiated between lung and colorectal adenocarcinoma. Primary and metastatic lung adenocarcinomas show a cytokeratin 7+/cytokeratin 20- staining pattern, while colorectal adenocarcinomas stain cytokeratin 7-/cytokeratin 20+. Cytokeratin staining is helpful in the diagnostic differentiation of metastatic lesions from these two common primaries, and assists in determining the site of origin of metastatic lesions.

Keratin expression in human tissues and neoplasms

Keratin expression in human tissues and neoplasms Keratin filaments constitute type I and type II intermediate filaments (IFs), with at least 20 subtypes named keratin 1-20. Since certain keratin subtypes are only expressed in some normal human tissues but not others, and vice versa, various tissues have been subclassified according to the pattern of keratin staining. Simple epithelia generally express the simple epithelial keratins 7, 18, 19, and 20, while complex epithelia express complex epithelial keratins 5/6, 10, 14, and 15. When an epithelium undergoes malignant transformation, its keratin profile usually remains constant. The constitution and expression patterns of keratin filaments in human epithelial neoplasms are complex and often distinctive. In this article, we first briefly review the molecular and cell biology of keratin filaments. We then focus on the expression patterns of keratin filaments in various human neoplasms.

Expression of thyroid transcription factor-1, cytokeratin 7, and cytokeratin 20 in bronchioloalveolar carcinomas: an immunohistochemical evaluation of 67 cases

Distinguishing primary pulmonary adenocarcinoma from metastatic adenocarcinoma involving the lung is a common challenging task. The distinction between mucinous bronchioloalveolar carcinoma (BAC) and metastatic mucinous carcinoma of other sites, in particular, is difficult by routine histology. Immunohistochemical expression of thyroid transcription factor-1 (TTF-1), as well as cytokeratin 7 (CK 7) and cytokeratin 20 (CK 20), has proven diagnostic utility in discerning primary from metastatic neoplasms in the lung. Rigorous studies assessing the expression of these markers in BACs, particularly in regard to nonmucinous and mucinous subtypes, have not been performed. In this study, we evaluated the immunohistochemical expression of TTF-1, CK 7, and CK 20 in 67 BACs (48 nonmucinous, 12 mucinous, and 7 of mixed histology). Overall, 42 (63%) of the 67 BACs were positive for TTF-1. When stratified according to subtype, all 12 mucinous BACs were observed to be TTF-1 negative. This trend toward absence of TTF-1 expression in mucinous areas was also maintained among tumors with mixed histology. Sixty-three (94%) of 67 BACs were CK 7 positive, with no differences in expression observed upon subtype stratification. Three cases were noted to be positive for CK 20; all exhibited mucinous morphology. These results indicate that in contrast to the immunophenotypic profile exhibited by most pulmonary neoplasms, mucinous BACs are TTF-1 negative and may express CK 20. This suggests that in the context of differentiating mucinous BACs from extrapulmonary mucinous tumors metastatic to the lung, evaluation of TTF-1 and CK 20 expression may have limited diagnostic utility.

Cytokeratins 20 and 7 as biomarkers: usefulness in discriminating primary from metastatic adenocarcinoma

Metastatic adenocarcinoma from an unknown primary site is a common clinical problem. The use of cytokeratins 20 (CK20) and 7 (CK7) was proposed to identify the primary sites in this situation. In this review, the results of 29 studies were summarised and the difficulties of data comparison described. Most tumours retained the CK20 phenotype during metastasis, but lung, non-mucinous ovarian, and gastric adenocarcinomas showed statistically significant differences in CK20 expression in the reported primary and metastatic cases. Ductal breast carcinomas, lung and non-mucinous ovarian adenocarcinomas showed significant differences in CK7 expression when primary and metastatic tumours were compared. CK20 positivity alone indicates metastatic spread of adenocarcinoma in several organs. CK7 negativity is consistent with metastases of adenocarcinomas in the lungs, ovaries, liver or serous membranes. CK20/7 phenotyping of adenocarcinomas is a useful diagnostic tool if based on algorithmic and probabilistic approaches and a detailed database.

Immunocytochemical detection of bone marrow micrometastases in colorectal carcinoma patients, using a monoclonal antibody to villin

The search continues to find methods to more effectively distinguish colorectal carcinoma patients who could be separated into high-risk and low-risk categories. Investigators have reported on the detection of occult micrometastases in bone marrow using antibodies to cytokeratin, which is a marker of epithelial cells but which has no tissue specificity, as opposed to villin, a cytoskeletal protein that is specifically involved in the formation of brush-border microvilli in the small intestine and colon epithelium. Specificity and sensitivity of antibody to villin (ID2C3) and antibody to cytokeratin (A45-B/B3) were first studied in normal bone marrow and in a test system in which cancer cell lines were mixed in normal bone marrow. In a preliminary study including 16 colorectal carcinoma patients, we compared the number of villin-positive cells with cytokeratin-presenting cells. As A45-B/B3, ID2C3 was determined to be sensitive enough to detect one cancer cell in 10(6) hematopoietic cells. Staining of hematopoietic cells with irrelevant antibody and a light staining of megakaryocytes with ID2C3 limited the specificity of the method. In colorectal carcinoma patients, correlation between ID2C3 and A45-B/B3 was 94%. Sensitivity and specificity of ID2C3 antibody to villin were satisfactory. Its clinical relevance must be investigated in further studies.

Mucinous and nonmucinous bronchioloalveolar adenocarcinomas have distinct staining patterns with thyroid transcription factor and cytokeratin 20 antibodies

We studied 14 mucinous and 26 nonmucinous bronchioloalveolar adenocarcinomas (BACs) with thyroid transcription factor (TTF), cytokeratin (CK) 7, CK20, and villin to characterize their staining patterns with these antibodies and identify staining differences between the neoplasms. We also stained 11 mucinous colon adenocarcinomas with the same antibodies to compare their reaction patterns with mucinous BACs. All pulmonary neoplasms were confirmed pulmonary primary BACs. Three (21%) of 14 mucinous neoplasms had weak TTF reactivity in fewer than 25% of neoplastic cell nuclei, and the other 11 (79%) were nonreactive. In contrast, 24 (92%) of 26 nonmucinonus BACs were strongly TTF reactive. Eleven mucinous BACs (79%) had CK20 reactivity in more than 25% of neoplastic cells, whereas only 1 nonmucinous BAC (4%) had reactivity in fewer than 50% of the cells. One mucinous BAC (7%) had villin reactivity in approximately 10% of the neoplastic cells. All mucinous colon adenocarcinomas were diffusely reactive with CK20 and villin. Mucinous and nonmucinous BACs have disparate staining patterns with TTF and CK20. Mucinous BACs are usually TTF nonreactive and CK20 reactive, but nonreactive with villin, which distinguishes them from mucinous colon adenocarcinomas.

Colon signet ring cell adenocarcinoma: immunohistochemical characterization and comparison with gastric and typical colon adenocarcinomas

Colon signet ring cell adenocarcinomas are uncommon, high-grade neoplasms. Given their rarity, the question of primary colon or metastatic gastric adenocarcinoma frequently arises when signet ring cell carcinoma is seen in a colonoscopic biopsy or in biopsies procured from other regions of the body. A second related question regarding colon and gastric signet ring cell carcinomas is their immunophenotypic similarities with the glandular form of adenocarcinoma in each site. We studied the immunohistochemical phenotype of 14 colonic signet ring cell adenocarcinomas and compared them with immunophenotype of 27 gastric signet ring cell adenocarcinomas. We also compared the immunophenotype of the 27 gastric signet ring cell with the immunophenotype of 19 gastric gland-forming adenocarcinomas, and the immunophenotype of the 14 colonic signet ring cell adenocarcinomas to the immunophenotype of 20 colonic gland-forming adenocarcinomas to identify staining differences in the neoplastic cells of the two architectures. Antibodies studied were cytokeratins 7, 17, 19, and 20, CA 19-9, CA-125. estrogen receptor, and gross cystic disease fluid protein 15. Sixty-four percent of colon signet ring cell adenocarcinomas had either no staining or focal staining with cytokeratin 7 compared with diffuse staining in 63% of gastric signet ring cell adenocarcinomas (P = 0.016). Seventy-two percent of colon signet ring cell adenocarcinomas had diffuse staining with cytokeratin 20 compared with no or focal staining in 50% of gastric signet ring cell adenocarcinomas (P = 0.019). Fifty-seven percent of the colon signet ring cell adenocarcinomas had a cytokeratin 7 (-)/cytokeratin 20 (+) staining pattern compared with 11% of gastric signet ring cell adenocarcinomas (P = 0.004). Forty-four percent of gastric signet ring cell adenocarcinomas had a cytokeratin 7 (+)/cytokeratin 20 (-) pattern, compared with none of the colon signet ring cell adenocarcinomas (P = 0.004). The staining distribution of the antibody battery was similar in colon signet ring cell and colon glandular adenocarcinoma and gastric signet ring cell and gastric glandular adenocarcinomas. When signet ring cell adenocarcinoma is encountered in a colon biopsy, a colon primary is supported if the neoplastic cells have a cytokeratin 7 (-)/cytokeratin 20 (+) staining pattern, and a gastric primary is supported if they have a cytokeratin 7 (+)/cytokeratin 20 (-) staining pattern. The signet ring morphology at each site had an identical immunophenotype as the cells forming their glandular counterpart.

Cytokeratin profile relates to histological subtypes and intrahepatic location of intrahepatic cholangiocarcinoma and primary sites of metastatic adenocarcinoma of liver

AIMS

We evaluated the cytokeratin profile of intrahepatic cholangiocarcinoma with respect to its histological classification and intrahepatic location (peripheral vs. hilar), and compared its profile with that of a variety of metastatic adenocarcinomas in liver.

METHODS AND RESULTS

Expression of cytokeratins 7, 8, 18, 19 and 20 was immunohistochemically examined in intrahepatic cholangiocarcinoma (n = 77) and metastatic adenocarcinoma in liver (21 colorectal, 14 gastric, three gallbladder and three pancreatic cancers). Materials were autopsy or surgical specimens. Cytokeratins 7, 8, 18 and 19 were expressed in 75 (97%), 75 (97%), 59 (77%) and 71 (92%) cases of intrahepatic cholangiocarcinoma, respectively. Moderate and extensive expression of cytokeratin 18 was more frequent in the peripheral than in the hilar type. Moderate and extensive expression of cytokeratin 19 was seen in almost all cases of well-differentiated intrahepatic cholangiocarcinomas, while expression was decreased relatively in the moderately and decreased more in the poorly differentiated cases. While cytokeratin 20 was not found in non-neoplastic biliary epithelia or in well-differentiated intrahepatic cholangiocarcinomas, this cytokeratin was occasionally detectable in moderately and poorly differentiated intrahepatic cholangiocarcinomas and its expression was more frequent in the hilar type. Cytokeratin 20 expression was observed in 17 (81%) of metastatic adenocarcinomas in liver from colorectal regions, to a lesser degree in those from gastric regions, and was rare in those from gallbladder and pancreatic regions; cytokeratin 7 showed a reverse expression pattern in these metastatic adenocarcinomas in liver. The profile of cytokeratins 7 and 20 of metastatic colorectal and gastric carcinomas differed from that for intrahepatic cholangiocarcinomas, while that of metastatic gallbladder and pancreatic carcinoma was similar to that for intrahepatic cholangiocarcinomas. Moreover, cytokeratin 18 and 19 expression was significantly infrequent in metastatic gastric carcinomas than in intrahepatic cholangiocarcinomas and metastatic colorectal carcinomas.

CONCLUSION

The combined immunostaining of cytokeratins 7, 18, 19 and 20 is useful for the characterization of intrahepatic cholangiocarcinomas with respect to histological subtypes and intrahepatic location. It helps to differentiate intrahepatic cholangiocarcinoma from metastatic adenocarcinomas in liver and from colorectal and gastric regions; it also indicates the primary focus metastatic adenocarcinomas in livers.

Patterns of distribution of cytokeratins 20 and 7 in special types of invasive breast carcinoma: a study of 123 cases

Metastatic adenocarcinomas of unknown primary site are a common clinical problem. Invasive ductal carcinomas of the breast and some special types of invasive breast carcinoma are common sources of metastases. Immunohistochemical algorithms, such as a combination of cytokeratins 20 and 7, can be helpful in this situation. Detailed phenotyping of the different types and subtypes of primary invasive carcinomas and their metastases is an essential prerequisite for a successful search for an unknown primary tumor. A series of 123 primary invasive breast adenocarcinomas of special type and of 27 lymph node metastases was analyzed. Sections of selected blocks were stained with two monoclonal cytokeratin antibodies (CK20 and CK7) and evaluated as negative (no staining), focally positive or diffusely positive. Of the 123 carcinomas, 113 (92%) proved to be CK20 negative. Three of 82 (4%) invasive lobular carcinomas, three of 11 (27%) mucinous carcinomas, one of 10 (10%) tubular carcinomas, and one invasive papillary carcinoma stained diffusely with CK20. Additionally, a tubulolobular carcinoma and a medullary carcinoma showed focal CK20 positivity. One hundred twenty (98%) of the 123 tumors were CK7 positive, five of them only focally. One of the four solid invasive lobular carcinomas, one medually carcinoma, and one invasive papillary carcinoma were completely negative for CK7. Only two cases, one mucinous and one invasive papillary carcinoma, exhibited the CK20(+)/CK7(-) ("colorectal") pattern. One of the lymph node metastases was CK20(+); another was CK7(-). Like their ductal counterparts, invasive breast carcinomas of special type are usually CK20(-)/CK7(+); they generally retain this phenotype in their metastases. However, there are CK20-positive special-type breast carcinomas that can be confused with gastrointestinal or pancreaticobiliary carcinoma in metastases, especially if they are mucinous or invasive lobular.

Immunoexpression of villin in neuroendocrine tumors and its diagnostic implications

BACKGROUND

Villin, a 95-kd cytoskeletal protein associated with axial microfilament bundles of brush border microvilli, is mostly restricted to intestinal glandular tumors. Villin immunoexpression was recently observed in a small number of carcinoids of the intestinal tract and lung, but its significance in a broad category of neuroendocrine tumors has not been evaluated.

DESIGN

A total of 114 neuroendocrine tumors of different origins were tested for villin expression. They included gastrointestinal carcinoids (n = 30), lung carcinoids (n = 15), small cell carcinomas of the lung (n = 24), small cell carcinomas of other sites (n = 15), islet cell tumors (n = 8), Merkel cell carcinomas (n = 6), paragangliomas (n = 6), and others (n = 10). Nine round cell sarcomas were tested as well.

RESULTS

Villin immunoreactivity was present in 85% of gastrointestinal carcinoids and small cell carcinomas, but was found in only 40% of lung carcinoids. Other tumors tested were virtually negative for villin. In general, while cytoplasmic reactivity was most common, a characteristic apical membranous pattern simulating brush border was seen in 76% of the gastrointestinal carcinoids and in 50% of the lung carcinoids.

CONCLUSIONS

We found that villin was predominantly restricted to gastrointestinal neuroendocrine tumors (excluding islet cell tumors), although a small number of bronchial carcinoids may be positive as well. These results suggest a role for villin in the differential diagnosis of neuroendocrine tumors.

Lung adenocarcinomas metastatic to the brain with and without ultrastructural evidence of rootlets: an electron microscopic and immunohistochemical study using cytokeratins 7 and 20 and villin

Adenocarcinomas metastatic to brain from lung or colon may pose differentiation difficulties. Ultrastructurally, both may have brush borders with rootlets. This study examines the ultrastructural morphology and immunohistochemical expression of villin (associated with rootlets), cytokeratin 7 (present in lung adenocarcinomas), and cytokeratin 20 (present in colon adenocarcinomas) in 19 formalin-fixed sequential surgical biopsies of lung adenocarcinomas metastatic to brain as compared to 13 colonic adenocarcinoma metastases. Of lung tumor metastases, mucinous differentiation with rootlets was most common [6/19(32%)]. All colon tumor metastases were cytokeratin 7(-), 20(+), and profusely villin(+). Well-formed rootlets were seen. All lung metastases were cytokeratin 7(+) and 20(-). 5/6(83%) lung metastases with rootlets were focally villin(+). 12/13(95%) without rootlets were villin(-). Rootlets are extremely common in lung adenocarcinoma metastatic to brain. Villin immunoreactivity closely correlates with rootlets. Its distribution is a useful adjunct to cytokeratin 7 and 20 in differentiation of lung versus colon adenocarcinomas metastatic to the brain.