Utility of cytokeratin 7 for distinguishing chromophobe renal cell carcinoma from renal oncocytoma

Chromophobe renal cell carcinoma showing oncocytoma-like hyalinized and edematous stroma: A case report and review of the literature

A case of chromophobe renal cell carcinoma (CRCC) with abundant hyalinized and edematous stroma mimicking oncocytoma is presented. This stromal architecture in the current case has not been reported on CRCC to our knowledge. A further interesting finding is entrapped non-neoplastic tubules in the hyalinized and edematous stroma composing the tumor. These histological features, such as abundant hyalinized and edematous stroma containing non-neoplastic tubules, may be analogous to oncocytoma. We reported a unique case of CRCC and studied with light microscopy and immunohistochemistry.

CD2-associated protein in human urogenital system and in adult kidney tumours

We studied expression of CD2-associated protein (CD2AP) in human urogenital system and in adult kidney tumours. In the cortex of normal kidney, CD2AP was expressed in all types of tubules and in the glomeruli. Labelling was more intense in cytokeratin 7- and in Tamm-Horsfall-positive tubules than in proximal tubules. In the medulla, expression was observed in the collecting ducts. Urothelium and the epithelium of prostatic acini, seminal vesicles, seminiferous tubules, epididymal ducts, Fallopian tube, endometrium and endocervix as well as granulosa cells showed moderate to strong CD2AP positivity. In syncytiotrophoblast, the expression was weaker than in cytotrophoblast. Endometrial stroma was negative, but decidualised stroma was weakly positive. Clear cell renal cell carcinoma (RCC) (n=63) showed a weak expression. Type-I papillary RCCs (n=4) and papillary adenomas (n=3) were negative. The epithelium lining the cysts in multilocular cystic RCCs (n=3) and in cystic nephroma (n=1) was strongly positive. Chromophobe RCCs (n=2), oncocytomas (n=3) and urothelial carcinomas (n=2) were moderately positive. The results show that CD2AP displays a specific expression pattern in human urogenital organs and that distinct expression is shown in several types of kidney tumours but not in type-I papillary RCCs or in papillary adenomas.

The diagnostic utility of MOC31, BerEP4, RCC marker and CD10 in the classification of renal cell carcinoma and renal oncocytoma: an immunohistochemical analysis of 328 cases

AIMS

To demonstrate the diagnostic utility of MOC31, BerEP4, renal cell carcinoma marker (RCC Ma) and CD10 in the classification of RCC and renal oncocytoma, based upon a comprehensive immunohistochemical analysis.

METHODS AND RESULTS

Immunohistochemistry was performed on 328 samples consisting of 256 clear cell/conventional, 27 papillary, 28 chromophobe, five collecting duct, five unclassified RCCs and seven renal oncocytomas using antibodies MOC31, BerEP4 and antibodies against cytokeratins (KL-1, CAM5.2, 34betaE12, cytokeratin 7), RCC Ma, epithelial membrane antigen, E-cadherin, CD10, CD15 and vimentin. Multivariate analysis showed that MOC31, BerEP4, RCC Ma and CD10 have discriminatory value. MOC31 and BerEP4 chiefly labelled distal tubules of normal kidney while RCC Ma and CD10 labelled the proximal tubules. Twenty-three chromophobe RCCs (82%) were reactive for MOC31, while only four clear cell RCCs and three papillary RCCs were positive for this marker. Clear cell RCCs were characterized by a high positive rate for CD10 (82%) and a low positive rate for BerEP4 (27%). Papillary RCCs frequently coexpressed RCC Ma and BerEP4 (51%). All renal oncocytomas were negative for MOC31 and CD10.

CONCLUSIONS

MOC31 has diagnostic merit in discerning chromophobe RCC. The CD10+/BerEP4- profile and RCC Ma+/BerEP4+ profile achieve moderate sensitivity and good specificity for clear cell RCC and papillary RCC, respectively. The non-reactivity for both MOC31 and CD10 is helpful in distinguishing renal oncocytoma from RCC. When properly selected, antibodies have immunohistochemical diagnostic utility for the classification of renal cortical epithelial tumours.

Best Practice No 180. Nephrectomy for renal tumour; dissection guide and dataset

Renal tumours constitute 2.5% of all malignancies and are among the 10 most common malignancies in the UK. Most of these are renal cell carcinomas (RCC) of various subtypes. Although historically RCC has been shown to be resistant to radiotherapy and chemotherapy, recent data suggest that the use of biological treatments, such as adjuvants, may be beneficial in patients with disease that has progressed at the time of presentation. The accurate diagnosis, staging, and grading of RCC is now a crucial element in optimal patient management. There are data to support the importance of histological type, tumour size, stage (especially patterns of extrarenal spread), and grade in determining outcome, and these data have been used to develop the published classification (Heidelberg/Rochester), staging (TNM), and grading (Fuhrman) systems. This article describes a dissection and histological sampling protocol that has been shown to increase the yield of staging information, a guide to histological classification and grading, and finally a minimum dataset for the completion of a satisfactory pathology report.

Expression of epithelial cell adhesion molecule (EpCam) in renal epithelial tumors

EpCam is an epithelial adhesion molecule expressed in a broad range of carcinomas. Clinical trials with specific humanized anti-EpCam antibodies have shown promising results and have been inaugurated in renal cell carcinoma (RCC) therapy. To study the EpCam expression profile, primary renal cell neoplasms as well as corresponding metastases were evaluated by immunohistochemistry in tissue microarrays. EpCam expression in oncocytomas and chromophobe RCCs was determined on conventional large sections. Moderate or strong EpCam expression was found in eighteen percent of clear cell (n=147), 75% of chromophobe (n=12), and 55% of papillary RCCs (n=20), but not in oncocytomas (n=3). On large sections, 90% of chromophobe RCCs (n=20) showed a strong and homogeneous positivity, whereas oncocytomas (n=15) revealed EpCam positivity in single tumor cells or small clusters. Fourteen percent of RCC metastases (n=97) showed EpCam expression. Patients with EpCam expressing clear cell RCC showed a trend toward a better prognosis in a Cox regression analysis including stage, grade, and necrosis. The data suggest EpCam as a potential therapeutic target in a subset of patients with RCC. In addition, expression patterns of EpCam could become a helpful tool in the discrimination of chromophobe RCC and oncocytoma.

Chromophobe renal cell carcinoma: a comparative study of histological, immunohistochemical and ultrastructural features using high throughput tissue microarray

AIMS

In some cases distinction between chromophobe renal cell carcinoma (CRCC), oncocytoma and clear cell (conventional) renal cell carcinoma (eosinophilic variant) using routine light microscopy remains problematic. The present study investigates the level of agreement in the diagnosis of CRCC, as well as the histological features most frequently used for this diagnosis by two pathologists with a special interest in renal neoplasia. The sensitivity and specificity of immunohistochemical markers in cases with overlapping histological features in the diagnosis of CRCC were also studied. Electron microscopy was performed, as a diagnostic gold standard, on all of the cases.

METHODS AND RESULTS

Thirty-two renal tumours with predominantly eosinophilic cytoplasm were reviewed in a blinded fashion by two pathologists. The diagnosis and morphological features used to render each diagnosis were tabulated. Validation of the utility of keratin 7 and 20, epithelial membrane antigen (EMA), vimentin, CD10, parvalbumin, RCC antigen, antimitochondrial antibody and Hale's colloidal iron was performed by the construction of a tissue microarray (TMA) master block. Based on histological criteria alone, overall agreement on the diagnosis of these tumours was reached in 69% of the cases, while there was total disagreement in 12%. In 59% of the cases, total agreement was reached in classifying the case as a CRCC based on histology alone. Kappa statistics for interobserver variability were calculated as only slight agreement (kappa = 0.3). The histological features most frequently associated with a diagnosis of CRCC were accentuated cell borders (87%) and a combination of hyperchromatic wrinkled nuclei (79%) and perinuclear halos (74%). The most sensitive and specific marker for CRCC was parvalbumin (sensitivity 0.91; specificity 1.0). The immunohistochemical profile of EMA+/ vimentin- was useful but had low specificity (sensitivity 0.75; specificity 0.4). CD10 had the highest sensitivity (1.0) but worst specificity (0.25) for CRCC. Keratin 7 had high sensitivity (0.83) but fairly low specificity (0.37) for CRCC. Hale's colloidal iron and the RCC antigen marker were not contributory. Finally, the antimitochondrial antibody was found to be fairly sensitive (0.83) for excluding CRCC.

CONCLUSIONS

A small but significant proportion of renal tumours with cells having eosinophilic cytoplasm cannot be classified, even by experienced pathologists, based on histology alone. In these cases it is imperative to use markers with known sensitivity and specificity for the diagnosis of CRCC.

Caractérisation immunohistochimique des principaux types histologiques de tumeurs rénales épithéliales étudiées par tissue-arrays sur une série de 310 cas

OBJECTIVE

Diagnosis of renal epithelial tumours of adult is often easily made. Nevertheless, it can be difficult to distinguish clear cell carcinoma (CCC) and chromophobe carcinoma (CCHRO), or the eosinophilic variants of CCC and CCHRO with papillary carcinoma (CTP) and oncocytoma (ONCO). The objective is to study and validate immunohistochemical phenotypes of these tumours and to evaluate if they are helpful and to define a diagnostic strategy.

MATERIALS AND METHODS

310 tumours (75 CCC, 89 CTP, 50 CCHRO and 96 ONCO) were collected and put on 4 tissue-arrays blocks. Immunohistochemical stainings were performed with some usual antibodies: pancytokeratin AE1-AE3, EMA, vimentin, CD10, CK7, CK20 and RCC (Renal Cell Carcinoma).

RESULTS

Pancytokeratin AE1-AE3 is expressed mainly in CTP (82.5%). The cytoplasmic staining of EMA is seen in almost all CCHRO (98%) and more than half of CTP (57%). Vimentin is rather specific of CCC (54.5%) and CTP (85%) whereas it is negative in ONCO and CCHRO. CD10 is expressed in the majority of CCC (86.5%) and in some of CTP and CCHRO 65 and 39% respectively. CK7 is rather specific of CTP and CCHRO with 79 and 81.5% of positivity rate. Based on statistical analysis, we have built a diagnostical tree allowing to distinguish 79% of tumours using only three antibodies: CK7, vimentin and CD10.

CONCLUSION

CCC are CK7-/Vim-/CD10+ or CK7-/Vim+; CTP are CK7+/Vim+; CCHRO are CK7+/Vim-; and ONCO CK7-/Vim-/CD10-. In the oncocytoma/chromophobe group, ONCO are more often CK7-/EMA- and CCHRO CK7+/EMA+.

The genetics of renal oncocytosis: a possible modelfor neoplastic progression

Renal oncocytosis is a rare condition characterized by the presence of numerous oncocytomas and oncocytic changes in the renal tubules. Other than oncocytomas associated with the Birt-Hogg-Dube (BDH) syndrome, the genetics of oncocytosis is not known. Whether oncocytomas and oncocytosis are similar to BDH syndrome, in which the tumors diploid (as most oncocytomas are), or show chromosomal losses may be significant regarding the observation that in oncocytosis, there frequently is morphological evidence of progression to chromophobe carcinoma. Here we report on the case of a 69-year old male who underwent a staged procedure of partial nephrectomy on the left side and right radical nephrectomy for multiple renal tumors. The tumors were studied by routine hematoxylin and eosin morphology, immunohistochemistry, cytogenetics, and loss of heterozygosity analysis. Both kidneys had numerous oncocytic neoplasms morphologically progressing from oncocytomas to hybrid tumors with chromophobe carcinoma. Genetic studies demonstrated progression from normal cytogenetics to chromosomal losses similar to those in some oncocytomas and in chromophobe carcinomas. The genetics of this apparently nonfamilial oncocytoma differs from that of BDH syndrome and is characterized by losses involving chromosomes 1, 14, 21, and Y. To our knowledge, this is the first report of the genetic and cytogenetic findings in oncocytosis not related to BDH syndrome and may suggest a possible model of progression from oncocytoma to chromophobe renal cell carcinoma.

Accuracy and Clinical Role of Fine Needle Percutaneous Biopsy With Computerized Tomography Guidance of Small (Less Than 4.0 Cm) Renal Masses

PURPOSE

We evaluated the accuracy and clinical role of fine needle percutaneous biopsy of solid renal masses 4.0 cm or smaller with helical computerized tomography (CT) guidance.

MATERIALS AND METHODS

In 88 consecutive patients (mean age 61 years) 88 biopsies were performed. Median tumor size was 2.8 cm. Tumor biopsy was performed with an 18 gauge needle using helical CT guidance in an outpatient setting. At least 2 whole cores per tumor were obtained.

RESULTS

Biopsy material was insufficient for analysis in 3 (3.4%) procedures. Median tumor size of failed biopsies was 3.0 cm. There were 5 (5.6%) biopsies which revealed fibrosis and were considered inconclusive. A benign lesion was found in 14 (15.9%) biopsies. In the 66 biopsies positive for malignancy there were 65 cases of renal cell carcinoma and 1 lymphoma. A total of 62 patients underwent surgery. Biopsy changed tumor management in 42 (47.8%) patients who avoided radical nephrectomy, 13 of whom had a lesion which did not require surgery, 1 with a lymphoma and 28 who were treated with partial nephrectomy. Biopsy accuracy for histopathological tumor type and Fuhrman nuclear grade was 92% and 69.8%, respectively. No substantial morbidity occurred.

CONCLUSIONS

Fine needle biopsy of small renal masses could select benign lesions for which observation might be an alternative to surgery. The accuracy of fine needle biopsy in identifying histological tumor type was high. However, biopsy was less accurate in evaluating Furhman grade. Biopsy with helical CT guidance could be a key point in tailored management of small solid renal masses and provide important information to those patients harboring renal masses.

Renal oncocytosis presenting in childhood: a case report

Renal oncocytosis is a rare condition in which a spectrum of oncocytic lesions, including oncocytomas, diffusely involve the kidney. Few cases have been reported and all were in adult patients. We report here such a case in a 12-year-old girl. In addition to the unusual age at presentation, this case is remarkable for its heterogeneous tumor morphology, with some areas containing chromophobe carcinoma-like cells. Electron microscopy, immunohistochemistry, Hale's colloidal iron staining, and cytogenetics were performed to further evaluate the different morphologic areas. Our results suggest that the cells in the chromophobe carcinoma-like areas do not fulfill all the diagnostic criteria of chromophobe carcinoma. We caution pathologists in making a malignant diagnosis in such cases, especially in younger patients.

Chromophobe renal cell carcinoma

BACKGROUND

Chromophobe renal cell carcinoma (CRCC) is often associated with a favorable prognosis. However, to the authors' knowledge, only few clinical data are available regarding this variant of tumor. In the current study, the authors report their experience with CRCC over the last 14 years.

METHODS

Since 1989, 61 patients have been treated at the study institution for CRCC. Tumor characteristics and patient outcome were analyzed retrospectively. Data were obtained from the patients' medical records.

RESULTS

The mean age of the patients was 58 years. Of the 61 tumors, 68.8% were discovered incidentally. The mean tumor size was 6.9 cm. Fifty-seven patients (93.4%) were treated with radical nephrectomy and 4 patients (6.6%) underwent partial nephrectomy. According to the 1997 TNM classification, the pathologic tumor stage was T1 in 65.6% of cases, T2 in 31.1% of cases, and T3a in 3.3% of cases. All tumors were staged as N0M0. Nuclear grade was low (1 or 2) in 88.5% of cases. In no case of CRCC was a sarcomatoid component observed. At a mean follow-up of 49.5 months (range, 5-135 months), no patient had experienced tumor recurrence or disease progression, and none had died of renal carcinoma.

CONCLUSIONS

In the authors' experience, CRCC carries an excellent prognosis, possibly due to the high rate of low-stage and low-grade tumors.

Update on oncocytoma

Oncocytoma is the most common benign solid renal tumor, comprising roughly 5% of resected renal masses. Typically discovered incidentally, oncocytoma is generally asymptomatic and very rarely metastasizes; however, multifocal disease and coexistence with renal cell carcinoma can occur. No currently used imaging techniques can reliably distinguish between oncocytoma and malignant lesions; therefore, patients must undergo resection, or in certain circumstances, biopsy, to definitively establish diagnosis. Careful attention to pathologic features and the adjunctive use of immunostains can aid in discriminating oncocytoma from other renal tumors characterized by granular, eosinophilic cytoplasm, especially chromophobe renal cell carcinoma. Nephron-sparing and laparoscopic surgical approaches can be used to treat appropriately selected patients.

Immunohistochemical profile of common epithelial neoplasms arising in the kidney

To distinguish common epithelial tumors arising in the kidney may have significant implications, in terms of molecular ontogeny and prognosis. It is important to investigate the distribution of immunoexpression of commonly used markers among renal neoplasms and to develop a useful panel as an adjunct to histologic examination, which could lead to the accurate diagnosis of both primary and metastatic tumors. Immunohistochemical stains for CD10, vimentin (VIM), E-cadherin (E-CD), cytokeratins (CK) 7, 8, 19, and 20, high molecular weight keratin (HCK), and peanut lectin agglutinin (PL) (Arachis hypogaea) were performed on 45 (96 for CK7, CK20) conventional (CC), 20 papillary (PC), and 6 (24 for CK7, CK20) chromophobe renal carcinomas (CPC); 12 oncocytomas (OC); 5 collecting duct carcinomas (CDC), and 25 urothelial carcinomas of the renal pelvis (UC). Reactivity for CD10 was evaluated on the basis of the presence of cell surface staining; that for all CKs, cytoplasmic/membranous staining; and that for PL, luminal staining. Both CD10 and VIM were predominantly expressed in CC and PC; E-CD in CPC, OC, and UC; CK7 in PC, CPC, and UC; CK8 and CK19 in CDC and UC; CK20 in UC; HCK in CDC and UC; and PL in CDC. CC and OC were predominantly CK7-/CK20-; PC, CK7+/20-; CPC, CK7+/CK20- or CK7-/CK20-; and UC, CK7+/CK20- or CK7+/CK20+. CDC showed slight predominance of CK7-/20- over CK7+/CK20-. CC was most frequently CD10+/CK7-/HCK-/PL-; PC, CD10+/CK7+/HCK-/PL-; CPC, CD10-/CK7+/HCK-/PL-; OC, CD10-/CK7-/HCK-/ PL-; CDC, CD10-/CK7+/HCK-/PL+ or CD10-/CK7-/ HCK+/PL+; and UC, CD10-/CK7+/HCK+/PL-. Discriminant analysis suggested that CD10/CK7/HCK/PL may be a useful primary immunopanel for distinguishing among CC, PC, CDC, and UC.

Expression profiling of human renal carcinomas with functional taxonomic analysis

BACKGROUND

Molecular characterization has contributed to the understanding of the inception, progression, treatment and prognosis of cancer. Nucleic acid array-based technologies extend molecular characterization of tumors to thousands of gene products. To effectively discriminate between tumor sub-types, reliable laboratory techniques and analytic methods are required.

RESULTS

We derived mRNA expression profiles from 21 human tissue samples (eight normal kidneys and 13 kidney tumors) and two pooled samples using the Affymetrix GeneChip platform. A panel of ten clustering algorithms combined with four data pre-processing methods identified a consensus cluster dendrogram in 18 of 40 analyses and of these 16 used a logarithmic transformation. Within the consensus dendrogram the expression profiles of the samples grouped according to tissue type; clear cell and chromophobe carcinomas displayed distinctly different gene expression patterns. By using a rigorous statistical selection based method we identified 355 genes that showed significant (p < 0.001) gene expression changes in clear cell renal carcinomas compared to normal kidney. These genes were classified with a tool to conceptualize expression patterns called "Functional Taxonomy". Each tumor type had a distinct "signature," with a high number of genes in the categories of Metabolism, Signal Transduction, and Cellular and Matrix Organization and Adhesion.

CONCLUSIONS

Affymetrix GeneChip profiling differentiated clear cell and chromophobe carcinomas from one another and from normal kidney cortex. Clustering methods that used logarithmic transformation of data sets produced dendrograms consistent with the sample biology. Functional taxonomy provided a practical approach to the interpretation of gene expression data.

Cytokeratin 7: a useful adjunct in the diagnosis of chromophobe renal cell carcinoma

AIMS

The histopathological diagnosis of chromophobe renal cell carcinoma can present a diagnostic challenge, as these tumours can resemble either conventional renal cell carcinoma or oncocytoma. The aim of this study was to determine whether cytokeratin 7 expression is of practical use in the distinction of these three entities.

METHODS AND RESULTS

A total of 40 cases previously diagnosed as either chromophobe renal cell carcinoma, conventional renal cell carcinoma or oncocytoma were identified. A representative section of each was stained with H&E and cytokeratin 7. Following independent review of the cases by three pathologists, a consensus diagnosis for each case was reached and the pattern of cytokeratin 7 staining was assessed. There were 12 cases of chromophobe renal cell carcinoma in the study, all of which showed a characteristic peripheral membrane pattern of staining for cytokeratin 7. Seventeen of the 18 cases of conventional renal cell carcinoma studied were negative for cytokeratin 7, while one case showed weak focal staining of <5% of the cells. The 10 cases of oncocytoma showed patchy weak to moderate cytoplasmic expression of cytokeratin 7, without the characteristic peripheral membrane accentuation seen in the chromophobe carcinomas.

CONCLUSIONS

Immunohistochemical staining for cytokeratin 7 appears to be a useful adjunct in the diagnosis of chromophobe renal cell carcinoma, and in distinguishing this tumour from both oncocytoma and conventional renal cell carcinoma.

Diagnosing primary and metastatic renal cell carcinoma: the use of the monoclonal antibody 'Renal Cell Carcinoma Marker'

The diagnosis of primary or metastatic renal cell carcinoma (RCC) can be difficult, especially in small biopsies, because of the wide variety of histologic appearances and clinical presentations that RCC can assume. An immunomarker specific for RCC is currently not available. We tested the relevant diagnostic use of the Renal Cell Carcinoma Marker (RCC Ma), a monoclonal antibody, against a normal human proximal tubular brush border antigen. Immunostaining using RCC Ma and the avidin-biotin-peroxidase complex technique was performed on archival tissues from primary and metastatic tumors of renal or nonrenal origin. A total of 122 of 153 primary RCCs (79.7%) were positive [clear cell (84%), papillary (96%), chromophobe (45%), sarcomatoid (25%), and collecting duct (0%)], with > or =10% of tumor cells stained in 93% of cases. None of the 64 primary renal tumors other than RCC, including 15 oncocytomas, was positive. Fifteen of 146 (10.2%) nonrenal primary tumors were positive (5 of 17 breast tumors, 8 of 8 parathyroid adenomas, and 2 of 7 embryonal carcinomas). Forty-two of 63 (67%) metastatic RCCs were positive with > or =10% of cells being stained in 83% of them. Two of 108 (2%) metastases from tumors other than RCCs were positive, both of which were metastatic breast carcinomas; however, only 10% (2 of 19) of metastatic breast carcinomas were positive. RCC Ma is an excellent marker for primary RCC, which should facilitate its diagnosis in a small biopsy. Although RCC Ma remains highly specific (98%) for metastatic RCC, a negative result may not rule out metastatic RCC because of a rather low sensitivity and a focal staining pattern in some of the positive cases. RCC Ma may also facilitate the differential diagnosis between oncocytoma and other types of RCC when they are composed mostly of eosinophilic cells.