Utility of cytokeratin 7 and 20 subset analysis as an aid in the identification of primary site of origin of malignancy in cytologic specimens

Serous cavity metastasis: Evaluation of unknown primary

Malignant effusions can occur in patients with neoplasia. Once a metastatic diagnosis is confirmed, the primary site of origin of malignancy needs to be ascertained. This task can be challenging without a prior history of malignancy. In some patients their effusion may be the initial presentation of an underlying malignancy. Metastases usually present with a dual population of mesothelial and malignant cells. Combining cytomorphologic examination with ancillary testing such as immunocytochemistry can help identify the origin of the foreign malignant cell population. Helpful architectural clues include a single cell pattern, solid cell ball pattern, single file arrangement, papillary formation, psammoma bodies and background mucin. Useful cellular features include the presence of signet ring cells, small cells, pleomorphic and multinucleated giant cells, squamous cells, spindle cells and pigmentation. Rarely, despite an extensive work-up the primary site of origin for a malignant effusion may remain unresolved. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Cytopathologic Diagnosis of Serous Fluids.

An immunohistochemical expression of CK5/6, CK7, and CK20 on cell blocks in metastatic cervical lymphadenopathy

Background

The neck is a common site of both primary and secondary malignancies. Many tumors from the head and neck (oral cavity, larynx, and pharynx), lung, and gastrointestinal tract metastasize to cervical lymph nodes. At most times, tumors are diagnosed by morphology, sometimes it is difficult to diagnose an unknown primary presenting as metastatic lymphadenopathy solely on the basis of morphology. Specific histological cell types can be confirmed by the use of immunohistochemistry.

Aim

The present study evaluated the utility of cell block over fine-needle aspiration cytology (FNAC) and immunohistochemical expression of CK5/6, CK7, and CK20 in metastatic cervical lymphadenopathy.

Methods:

This prospective study design was used on a total of 50 cases. FNAC smears and cell blocks were made in all the cases. All the cell blocks were compared with FNAC findings and further subjected to immunohistochemical (IHC) analysis. The necessary statistical analysis was done.

Results and Conclusion

Our study showed that the combined use of the cell block technique and FNAC was more useful and sensitive in diagnosing the metastatic cervical lymph nodes and the accuracy can be further improved by the use of IHC on the cell blocks. The combined use of CK5/6, CK7, and CK20 in metastatic cervical lymphadenopathy is helpful in diagnosing squamous cell carcinoma and adenocarcinoma with known/unknown primary sites.

Does Cancer of Unknown Primary (CUP) Truly Exist as a Distinct Cancer Entity?

Cancer of unknown primary (CUP) designates an enigmatic cancer entity with histologic confirmation of malignancy from a metastasis but no identifiable primary tumor in spite of a thorough diagnostic work-up. In this review, we discuss the validity of CUP as a distinct cancer entity as well as diagnostic pitfalls. As arguments against a distinct entity, the diagnosis of CUP is erroneous in some cases. Diagnostic pitfalls include incomplete diagnostics, uncertainty in classifying a lesion as either primary or metastasis and mistaking a relapse of an antecedent malignancy as CUP due to histologic and immunohistologic disparities. Given the high frequency of prior malignancies in CUP patients, relapse of an antecedent cancer should always be carefully excluded. Gene expression profiling-based classifier assays aim at aligning the molecular profile of CUP patients with established primary cancer patterns for highest congruency in order to identify the putative primary and treat accordingly. However, the spectrum of predicted putative primaries by molecular techniques is somewhat at odds with the primaries identified in autopsy series. Also, a first randomized clinical trial did not show superiority of primary-tailored therapy over unspecific platinum-based chemotherapy. CUP cases share an aggressive clinical course, atypical metastasis pattern, rapid progression of metastases, a generally poor response to chemotherapy and dismal outcome as distinct clinical features. Metastatic spread appears to take place in the early stages of tumor evolution, with CUP metastases subsequently undergoing genetic evolution toward a chromosomally highly complex and instable karyotype independent from the primary tumor. In clinical practice, the diagnosis of CUP is valid when no primary tumor is detectable. Treatment should ideally offer broad spectrum coverage across numerous malignancies and be well-established in CUP as is the case for carboplatin/paclitaxel and cisplatin / gemcitabine in particular, but it should also cover the most likely putative primary. The diligent diagnosis of CUP is warranted for clinical trials, making the eligibility process particularly laborious. In conclusion, we deem CUP a distinct cancer entity and the diagnosis accurate in most patient cases.

Diagnosis and management of metastatic neoplasms with unknown primary

In cancer of unknown primary (CUP), metastases are clinically and histologically confirmed, but the primary tumor site remains elusive after extensive work-up. CUPs make up for 2-3% of all epithelial malignancies. The two prevailing histologies are adenocarcinomas and undifferentiated carcinomas, whereas squamous cell carcinomas, neuroendocrine carcinomas and rare histologies account for the remaining 10%. The diagnostic work-up in CUP relies strongly on a detailed immunohistological (IHC) analysis in order to characterize the tumor type, nowadays aided by molecular techniques. Diagnostics also include a thorough clinical examination, a basic lab draw with the most relevant tumor markers, and cross sectional imaging. Additional PET-CT is recommended in cervical lymph nodes suggestive of head and neck cancer and in limited metastases potentially treatable in curative intent. As for treatment, it is paramount to identify patients who fall into one of the six well defined "favorable" subset categories, namely extragonadal germ cell tumors, adenocarcinoma with isolated unilateral axillary lymph nodes in female patients, squamous cell carcinoma with neck lymph nodes, squamous cell carcinoma with inguinal lymph nodes, serous papillary peritoneal carcinomatosis in females and blastic bone metastasis in males with elevated PSA. These subsets are distinct both regarding the required treatment and the comparably favorable prognosis. Within the remaining "unfavorable" group, patients of colon and renal cancer type should be identified based on IHC and clinical picture, since the prognosis of these patients seems to improve with the use of therapy tailored to the presumed primary as well. For the few patients with limited metastases it should be assessed whether they are candidates for surgery, radiotherapy or surgery followed by irradiation in curative intent. The remaining majority of patients are treated with empiric palliative chemotherapy, typically a platinum - paclitaxel combination, though the level of evidence for this therapy recommendation is low. Gemcitabine alone or in combination can be used as an alternative. Decoding of the molecular profiles in CUP offers the prospect of targeted therapy with novel agents. However, there appears to be no uniform molecular pattern for CUP, and the observed molecular diversity thus poses a challenge to respective clinical trials.

Intermediate filament: structure, function, and applications in cytology

Intermediate filament (IF) constitutes an important cytoskeletal component in nearly all the vertebrate cells. IFs are present both in the cytoplasm and in the nucleus. They play an important role in providing mechanical strength of the cell and tissue, growth and regeneration, cell survival and apoptosis, and finally cell migration. IFs are also expressed differentially in different body tissues. Therefore, judicious use of IF may provide the diagnosis and confirmation of different malignancies. This is particularly helpful in the diagnosis of metastatic malignant tumor from an unknown primary. Expression of IFs particularly cytokeratin and vimentin is also related to prognosis of tumors. In this review, we have discussed the basic structure, dynamics, distribution of IF in cells, and its role in diagnosis of cytology. Possible prognostic roles of IF are also discussed.

Metastatic gingival tumor from rectal cancer diagnosed with CDX2

Metastatic tumors of the oral region are very rare, accounting for approximately 1% of intraoral malignant tumors. Caudal-related homeobox transcription factor (CDX2) regulates the development and differentiation of intestinal epithelial cells. We report herein a case of metastatic gingival tumor from rectal cancer after low anterior resection in which immunohistochemical analysis of CDX2 was useful for diagnosis of the origin. To the best of our knowledge, our case is the first report that immunohistochemical staining with CDX2 can contribute to diagnose metastatic gingival tumor from rectal cancer.

Carcinoma of unknown primary with a colon-cancer profile-changing paradigm and emerging definitions

Carcinoma of unknown primary (CUP), which accounts for about 3-5% of all new cancers, is a challenging heterogeneous entity with an unmet research need. Traditionally, CUP has been managed with broad-spectrum chemotherapy, but with the increasing availability of sophisticated diagnostic techniques and the emergence of new treatments that have been shown to be effective in specific cancers the one-treatment-fits-all approach to CUP might eventually no longer be valid. CUP in association with a colon-cancer profile (CCP-CUP) is an example of an emerging, specific CUP subset that seems to benefit from a tailored approach. CCP-CUP is identified by CK20 and CDX2-positive and CK7-negative immunohistochemistry and a clinical course consistent with that of patients known to have metastatic colon cancer. Our findings suggest that patients with CCP-CUP derive substantial benefit from the use of specific treatments developed for colon cancer and larger clinical trials are warranted to more definitely test this finding. In the era of molecular profiling, we expect that additional work with CCP-CUP and other CUP subsets will provide attractive tailored treatment alternatives, with efficacies that exceed the current one-treatment-fits-all approach.

CDX-2 expression in pulmonary fine-needle aspiration specimens: a useful adjunct for the diagnosis of metastatic colorectal adenocarcinoma

CDX-2 is a homeobox gene, which encodes a transcription factor that plays a vital role in the development and differentiation of intestinal epithelial cells. Recent studies showed that CDX-2 protein expression by immunohistochemistry (IHC) has a high predictive value for confirming the diagnosis of colorectal adenocarcinoma (ACA). The differentiation of primary pulmonary ACA from metastatic colorectal ACA can be extremely challenging on fine-needle aspiration (FNA). The results of immunostains for TTF-1, CK 7, and CK 20 may be controversial in the differential diagnosis. In this study, we evaluated the clinical utility of CDX-2 in lung FNA specimens. Cell blocks from 41 primary lung and 20 colorectal ACAs metastatic to the lungs were retrieved. Cell block sections were immunostained with a CDX-2 monoclonal antibody. Sensitivity and specificity of CDX-2 for colorectal ACA was 75 and 100%, respectively. All five cases negative for CDX-2 were moderately to poorly differentiated colorectal ACAs. Our study confirms that CDX-2 is a highly useful immunohistochemical marker for the differentiation of primary pulmonary ACA from colorectal ACA metastatic to the lungs in FNA specimens. Of diagnostic importance is the loss of CDX-2 immunoreactivity in poorly differentiated colorectal ACAs.

Immunocytochemical identification of carcinomas of unknown primary in serous effusions

Metastases from carcinomas of unknown primary site (CUP) in serous effusion are a common clinical problem. Immunocytochemistry was applied as an adjunct to the cytological diagnosis of metastatic carcinomas in serous effusions. Subjects of this study were 118 pleural, 53 peritoneal, and 9 pericardial effusions from 180 patients routinely investigated in the Institute of Cytopathology. Specimens were primarily stained according to Papanicolaou (Pap). The avidin-biotin-complex method (ABC) was secondarily applied for the visualization of immunologic reactions. We have used a panel of six monoclonal antibodies (CK 5/6, CK 7, CK 20, CA 125, TTF-1, and cdx 2) so as to identify the primary tumor site of metastatic carcinoma cells in serous effusions. Applying an algorithm of immunocytochemical marker constellations, we were able to correctly diagnose primary tumor sites in 86 of 101 (85.1%) patients with CUP syndromes. The best result was achieved for the identification of metastatic carcinomas of the ovaries (94.7%) and the lungs (88.1%). We established an algorithm comprising six immunocytochemical markers that enabled a correct diagnosis of primary tumor sites in 85.1%. The panel studied could be useful in diagnostic routine for the identification of primary tumors of unknown origin metastatic to the serous membranes.

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.

Reduced expression of cytokeratin 20 in colorectal carcinomas with high levels of microsatellite instability

High levels of microsatellite instability (MSI-H) result from abnormal nucleotide mismatch repair in a subset of sporadic colorectal carcinomas (CRC) and in most CRC of hereditary non-polyposis colorectal cancer syndrome. CRC with MSI-H have distinctive clinical-pathologic features, but the immunophenotype has not been studied extensively. We evaluated immunohistochemical expression of cytokeratin 7 (CK7), cytokeratin 20 (CK20), and pancytokeratin (panCK) in 44 CRC from 22 paired MSI-H and microsatellite-stable (MSS) cases matched for clinical-pathologic characteristics. The mean percentage of CK20+ tumor cells was 84 +/- 6% in MSS CRC but only 37 +/- 8% in MSI-H CRC (P = 0.0007). Thirty-two percent (7/22, 95% confidence interval 14-55%) of MSI-H CRC were CK20-, as contrasted with 9% (2/22, 95% CI 1-29%, P = 0.13) of MSS CRC. CK20 expression was inversely correlated with levels of MSI (rs = -0.45, P = 0.006). CK7+ was infrequent (16%, 7/44, 95% CI 7-30%) and panCK+ was universal, with no significant differences between MSI-H and MSS CRC. Our study shows that decreased or even absent CK20 expression is a phenotypic characteristic of MSI-H CRC and that MSI-H explains much of the subset of CRC that lack CK20 expression. Our results also indicate that regulation of CK20 gene expression involves molecular pathways that are altered by MSI-H.

Diagnosis of hepatocellular carcinoma: fine needle aspiration cytology or needle core biopsy

Needle core biopsy (NCB) has been the standard procedure for histopathologic diagnosis of hepatic lesions for more than 50 years. In recent years fine needle aspiration cytology (FNAC) has emerged as a minimally invasive, relatively inexpensive and a rapid method of pathologic evaluation of primary or metastatic hepatic masses. The specificity and the positive predictive value of FNAC is very high however, the sensitivity of the procedure widely ranges between 67% to 93%. The two major areas of diagnostic difficulties are differentiation of benign and non-neoplastic hepatic nodules from well differentiated HCC and identification of obviously malignant cells as HCC, cholangiocarcinoma, or metastasis. Preparation of cell blocks, immunohistochemical stains and application of other ancillary techniques are often helpful in difficult cases. In presence of characteristic features a diagnosis of HCC can be established on FNAC however, a negative result does not exclude malignancy. The role of pathologic diagnosis in the assessment of large hepatic masses is well established however, its role in the evaluation of small hepatic nodules (<3 cm) detected during surveillance of high risk patients is still evolving. Considering the overall advantages and cost-analysis, FNAC can be suggested as the initial method of choice for evaluation of hepatic masses in most clinical settings. However, the final choice of the diagnostic procedure should be decided on the basis of working clinical diagnosis and the institutional experience.

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.

Transitional cell carcinoma metastatic to the eye in a collared peccary (Tayassu tajacu)

A 15-year-old female collared peccary (Tayassu tajacu) was presented for ophthalmic examination following sudden onset of blindness. Bilateral retinal detachment was diagnosed, neoplasia suspected, and euthanasia performed. Widespread tumor dissemination was apparent at autopsy, and transitional cell carcinoma was diagnosed histologically. The tumor was identified as arising from the ovary. Epidemiologic features of this case are discussed.

[Coordinated expression of cytokeratin 7 and 20 in transitional carcinoma of the bladder: diagnostic usefulness]

BACKGROUND

Cytokeratins are intermediate filament proteins which are part of the framework of eucariotic cells. A characteristic pattern of expression of cytokeratins has been described for each type of epithelium. This pattern is maintained during the process of malignancy and metastasis. Immunohistochemical analysis of cytokeratins 7 and 20 (Ck 7 and Ck 20) has been considered particularly useful for identifying the origin of carcinomas.

METHODS

A total of 122 cases of transitional cell carcinoma of urinary bladder were studied immunohistochemically with monoclonal antibodies against Ck 7 and Ck 20. The peroxidase labelled-streptavidin biotin technique was performed. Cases were considered positive when at least 1% of tumoral cells were stained.

RESULTS

All cases investigated expressed Ck 7 whereas Ck 20 was positive in 75% of them. Reactivity for Ck 20 was always focal. No tumor was negative for Ck 7.

CONCLUSION

Ck 7+/Ck 20+ immunophenotype is highly characteristic of transitional cell carcinoma of urinary bladder, whereas Ck 7+/Ck 20- is less frequent. Immunohistochemical determination of these cytokeratins is useful for the diagnosis when tumors are poorly differentiated and for identifying the primary site of metastatic carcinomas.

Use of thyroid transcription factor 1, PE-10, and cytokeratins 7 and 20 in discriminating between primary lung carcinomas and metastatic lesions in fine-needle aspiration biopsy specimens

BACKGROUND

The distinction of a primary lung carcinoma from a metastatic lesion is important, because the treatment and prognosis differ for patients with these malignancies. Such a distinction can be difficult because of overlapping cytologic features. It has been shown that antibodies to thyroid transcription factor 1 (TTF-1) and PE-10 are fairly specific markers for primary lung tumors in histologic specimens. TTF-1 regulates the expression of surfactant protein production, and PE-10 is a monoclonal antibody against components of human surfactant proteins. The combination of cytokeratin 7 (CK7) and cytokeratin 20 (CK20) immunoprofiling has been helpful in the identification of the primary site of origin of lung tumors.

METHODS

In the current study, the authors evaluated the utility of TTF-1 and PE-10 immunostaining and also compared the staining with expression of CK7 and CK20 in the discrimination between primary lung tumors and metastatic lesions in 55 specimens from fine-needle aspiration (FNA) biopsies of the lung. Formalin fixed, paraffin embedded cell blocks from 35 primary lung tumors (16 adenocarcinomas, 8 squamous cell carcinomas, 6 large cell undifferentiated carcinomas, and 5 small cell carcinomas) and 20 metastatic carcinomas (6 breast lesions, 6 colon lesions, 3 urinary bladder lesions, 2 kidney lesions, 1 biliary tract lesion, 1 endometrial lesion, and 1 thyroid lesion) were immunostained with monoclonal antibodies to TTF-1, PE-10, CK7, and CK 20. Positive immunostaining for CK7, CK20, and PE-10 was based on cytoplasmic staining, whereas TTF-1 positive staining was based on nuclear staining of the neoplastic cells.

RESULTS

Positive immunostaining with TTF-1 and PE-10 was noted in six primary lung tumors (17%). One metastatic lesion (5%) and two metastatic lesions (10%) were positive for TTF-1 and PE-10, respectively. The CK7 positive/CK20 negative immunophenotype was noted in 30 primary lung tumors (86%) and in 11 metastatic lesions (55%). The CK7 negative/CK20 negative immunophenotype was seen in four metastatic lesions and in the remaining five primary lung tumors. The CK7 negative/CK20 positive and CK7 positive/CK20 positive immunophenotypes were seen in two and three metastatic lesions, respectively, but in none of the primary lung tumors. When a CK7 positive/CK20 negative adenocarcinoma also demonstrated either TTF-1 positive or PE-10 positive staining, it was likely that the adenocarcinoma was of pulmonary origin (P < 0.035; Fisher exact test). The specificity of such a combination for discriminating between primary and metastatic adenocarcinomas was 94%.

CONCLUSIONS

The results suggest that TTF-1, PE-10, or CK7/CK20 alone did not distinguish reliably between primary pulmonary tumors carcinomas and metastatic neoplasms of the lung in FNA biopsy specimens because of low sensitivity and specificity. The use of a panel of antibodies that includes CK7/CK20, TTF-1, and PE-10 may be helpful in discriminating between primary and metastatic adenocarcinomas of the lung. An adenocarcinoma is likely a primary lung tumor when it is of the CK7 positive/CK20 negative phenotype and demonstrates either TTF-1 positive or PE-10 positive staining.

Peritoneal carcinomatosis: image-guided peritoneal core biopsy for tumor type and patient care

PURPOSE

To assess image-guided peritoneal core biopsy for the diagnosis of tumor type and treatment of patients with peritoneal carcinomatosis.

MATERIALS AND METHODS

Thirty-five women (age range, 47-85 years; mean age, 69 years) prospectively identified in a gynecologic oncology center underwent 18-gauge core biopsy in omental cake (n = 25), peritoneal (n = 7), or adnexal (n = 3) sites. No complications of biopsy occurred. Standard hematoxylin-eosin analysis of the biopsy cores was supplemented by immunohistochemical markers to CA-125, carcinoembryonic antigen, cytokeratin 7, and cytokeratin 20. Diagnoses were validated with further multidisciplinary review, subsequent surgery, and response to specific chemotherapy.

RESULTS

In 27 (77%) of the 35 women, a confident primary site diagnosis was obtained with standard hematoxylin-eosin analysis of core biopsy material from the following sites: ovary (n = 22), breast (n = 2), colon (n = 2), and lymphoma (n = 1). The finding at hematoxylin-eosin analysis in another seven (20%) women was poorly differentiated adenocarcinoma with no definite primary site but with an immunohistochemical profile suggesting ovarian cancer (CA-125 positive, carcinoembryonic antigen negative, cytokeratin 7 positive, cytokeratin 20 negative). There was one false-negative biopsy result.

CONCLUSION

Image-guided peritoneal core biopsy with hematoxylin-eosin analysis supplemented with immunohistochemical analysis is a simple, safe, and accurate technique for providing site-specific diagnoses in women with undiagnosed peritoneal carcinomatosis.

Utility of CK7 and CK20 immunohistochemistry in the detection of synchronous breast and colon carcinoma in a pleural effusion: a case report and supporting survey of archival material

We present a case of synchronous breast and colon carcinoma in a pleural effusion, to our knowledge the first such reported case in the English-language literature. The patient was a 55-yr-old white female with known metastatic breast and colon carcinoma who developed a malignant pleural effusion which demonstrated two strikingly different populations of malignant cells by immunohistochemical study of cell block material. One cell population demonstrated a cytokeratin (CK)7+/CK20-/ER+ phenotype, while the other demonstrated a CK7-/CK20+/ER- phenotype, consistent with breast and colon origin, respectively. An immunohistochemical survey of archival breast and colon primary and metastatic carcinomas confirmed the established CK7+/CK20- phenotype of breast and CK7-/CK20+ phenotype of colon primary carcinomas, and the maintenance of this phenotype in metastases thereof. A survey of benign and malignant mesothelial lesions confirmed the absence of staining for estrogen receptor, but showed 6/10 cases weakly positive for CK20, which has not been described in other published series. This unusual case graphically illustrates the utility of cytokeratin subset immunohistochemistry in effusion cytology.

Cytokeratins 7, 17, and 20 reactivity in pancreatic and ampulla of vater adenocarcinomas. Percentage of positivity and distribution is affected by the cut-point threshold

We studied reactivity of cytokeratins (CK) 7, 17, and 20 in 64 pancreaticobiliary adenocarcinomas to examine the effect of different cut-point thresholds on "positive" results, compare ampulla of Vater and pancreas adenocarcinomas, and provide additional experience with CK17 reactivity. Almost all neoplasms had extensive CK7 reactivity. The number of CK20-positive cases decreased from 29 (45%; any stained cells) to 19 (30%; > 25% staining) to 14 (22%; > 50% staining) with an increasing threshold of reactive cells. Similar shifts in the distribution of CK7 and CK20 reactivity occurred when different thresholds of reactivity were used for a positive result. There were no differences in CK7 or CK20 reactivity in pancreas only, ampulla only, and neoplasms involving both sites. Of 64 adenocarcinomas, 29 (45%) had no or single-cell CK17 reactivity, and 19 (30%) had reactivity in more than 50% of neoplastic cells. Ampulla of Vater and pancreas adenocarcinomas have similar CK immunophenotypes that cannot assist in distinguishing ampullary from pancreatic neoplasms on endoscopically procured tissue. CK17 staining occurs in approximately 50% of pancreaticobiliary adenocarcinomas and is usually patchy. Single antibody staining results, especially CK7 and CK20 coordinate reactivity, are influenced by the reactivity threshold used.