- Email: [email protected]
Cytogenetic Analysis of a Series of 13 Renal Oncocytomas
0022-5347/04/1712-0602/0 THE JOURNAL OF UROLOGY® Copyright © 2004 by AMERICAN UROLOGICAL ASSOCIATION
Vol. 171, 602– 604, February 2004 Printed in U.S.A.
DOI: 10.1097/01.ju.0000109172.07081.16
CYTOGENETIC ANALYSIS OF A SERIES OF 13 RENAL ONCOCYTOMAS VALERIE LINDGREN,* GLADELL P. PANER, ATILLA OMEROGLU, STEVEN C. CAMPBELL,† W. BEDFORD WATERS, ROBERT C. FLANIGAN AND MARIA M. PICKEN From the Department of Pathology, University of Illinois at Chicago (VL), Chicago and Departments of Pathology (GPP, AO, MMP) and Urology (SCC, WBW, RCF), Loyola University of Chicago, Maywood, Illinois
ABSTRACT
Purpose: Only about 50 renal oncocytomas have been studied cytogenetically. They fall into 3 categories, namely 1—normal karyotype, 2—monosomy 1, often with Y chromosome loss, and 3—structural abnormalities of 11q13. Additional abnormalities may occur with transformation to chromophobe renal cell carcinoma, although exactly which one is unclear. We expanded the oncocytoma data base to shed light on changes that characterize transformation. Materials and Methods: A total of 14 oncocytomas from 12 patients were collected in 21⁄2 years. One tumor failed to grow but 13 were successfully karyotyped. Results: Seven tumors (53.8%), including 2 from 1 kidney, had normal karyotypes or abnormalities characteristic of normal kidney tissue. A total of 6 tumors from 5 individuals (46.2%) had chromosome 1 abnormalities. Monosomy 1 was detected in 2 single tumors and in both tumors in a bilateral case. Structural anomalies resulting in loss of the short arm of chromosome 1 were found in an additional 2 patients. Other abnormalities, including Y chromosome loss and monosomy 14, were observed but no abnormalities of 11q13 were seen. Conclusions: Our series confirms that 1p loss is the most common anomaly in oncocytoma. Additional studies are required to understand the transformation potential of this usually benign tumor, identify the putative 1p tumor suppressor gene and determine whether karyotypically normal tumors have molecular abnormalities of 1p. KEY WORDS: kidney; adenoma, oxyphilic; carcinoma, renal cell; chromosome aberrations; genes, tumor suppressor
Approximately 3.0% to 5.0%1 of renal tumors are classified histologically as oncocytoma, a typically benign epithelial tumor characterized by eosinophilic cytoplasm containing abundant mitochondria. The current diagnostic criteria for kidney tumors are largely based on (cyto)genetic abnormalities specific to each tumor class.2 However, according to the 2003 Mitelman et al data base of chromosome abnormalities in cancer only slightly more than 50 oncocytomas have been cytogenetically analyzed to date.3 Moreover, when morphological or genetic criteria are the basis for classification, gray areas arise in distinguishing oncocytoma and chromophobe renal cell carcinoma. Furthermore, to our knowledge no genes involved in the genesis of oncocytoma have been clearly identified. Karyotypes in oncocytomas fall into 3 categories, namely 1—normal, 2—loss of chromosome 1 or the short arm of chromosome 1, loss of the Y chromosome and occasionally monosomy 14, and 3—structural rearrangements involving chromosome 11 band q13.3–7 The majority of cytogenetic reports include a single oncocytoma. Only 4 small series of oncocytomas have been published that include more than 2 tumors.4 –7 Since most publications included only cases of abnormal karyotypes, the percent of tumors in the different cytogenetic categories is unclear. Furthermore, the clinical significance of each karyotype is unresolved. We analyzed cytogenetically a series of morphologically well characterized oncocytomas.
MATERIALS AND METHODS
Of 133 kidneys surgically removed by partial or radical nephrectomy at Loyola University Medical Center from August 1998 to February 2001, 16 (12.0%) from 12 patients contained renal oncocytoma. Fresh specimens for cytogenetic analysis were available in 14 oncocytomas from these patients. The diagnosis of oncocytoma was based on previously published criteria.1, 8 Immunohistochemistry, colloidal iron staining and electron microscopy studies confirmed the diagnosis. Immunohistochemical stains included pankeratin, cytokeratin 7 and vimentin. Electron microscopic studies were performed as previously described.9 For cytogenetic analysis fresh samples from each tumor were disaggregated with collagenase, physically disrupted and put into culture for 1 to 10 days with Eagle’s minimal essential medium. Harvesting and staining followed standard cytogenetic techniques. When possible, 20 cells per tumor were examined. RESULTS
The 12 patients in this series included 7 males and 5 females 42 to 84 years old (median age 69). Table 1 lists patient clinicopathological features. Masses were bilateral in 4 of 12 patients. All bilateral oncocytomas occurred synchronously. Multifocality within a single kidney was observed in patients 5 and 10. Thus, 5 of 12 patients (42.0%) had more than 1 synchronous oncocytoma. In patient 10 in addition to oncocytomas, there were multiple microscopic oncocytic nodules in each kidney (oncocytosis). Oncocytomas in 10 of the 12 patients (83.3%) demonstrated a pure histology. In patients 5 and 9 there were focal areas (approximately 25%) of cells with cytoplasmic membrane condensation and prominent perinuclear clearing (chromophobe-like cells) in a background of classic oncocytic cells. These 2 tumors showed focal reticular cytoplasmic staining with Hale’s colloidal
Accepted for publication September 19, 2003. Study received institutional review board approval. * Correspondence: Department of Pathology (MC 750), University of Illinois Medical Center at Chicago, Building 911, Room 211A, 840 S Wood St., Chicago, Illinois 60612 (telephone: 312-355-3619; FAX: 312-413-0156; e-mail: [email protected]). † Financial interest and/or other relationship with Novartis and Aventis. 602
CYTOGENIC ANALYSIS OF RENAL ONCOCYTOMA TABLE 1. Clinicopathological summary of oncocytoma No. pts 12 No. involvement: Unilat 8 Bilat 4 Dominant tumor nodule size (cm) 1.0–12.2 No. histological morphology:* Pure oncocytoma 12 Hybrid oncocytoma with focal chromophobe 2 Ca features Oncocytoma with oncocytosis 2 No. nephrectomy:* Partial 5 Radical 11 * Bilateral tumors in 4 patients, or a total of 16 oncocytomas.
iron and focal positivity for cytokeratin 7. However, all other cases were negative for these stains. Other stains showed positivity for pankeratin (16 of 16 tumors) and negativity for vimentin (16 of 16 tumors). Electron microscopic studies were performed on 13 tumors and all had abundant mitochondria. In patient 6 solitary tumors (1 per kidney) were noted. In patient 10, 2 tumors from the same kidney were studied. In all other cases a single tumor was submitted even when there were multiple tumors. One specimen in patient 4 failed to grow but results were obtained from 13 tumors (table 2). A total of 7 tumors from patients 1, 3, 5 and 8 to 10 demonstrated only normal cells, nonclonal abnormalities or cells with trisomy 7 and/or a lack of the Y. Trisomy 18 was detected in patient 1 but only in a minority of cells. The 6 remaining tumors from 5 patients had abnormalities of chromosome 1, including monosomy 1 in a total of 4 tumors in patients 2, 6 and 12, and structural abnormalities resulting in loss of the whole short arm of chromosome 1 in 2 tumors in patients 7 and 11, respectively. The tumor in patient 7 had multiple, complex structural abnormalities but without apparent loss of material except of 1p. Two tumors in the right kidney of patients 6 and 12, respectively, had monosomy 14 in addition to monosomy 1. Patient 2 lacked chromosome 21 and had an isochromosome for 9p with concomitant 9q loss. DISCUSSION
In our series of 14 pathologically well-defined oncocytomas 13 were successfully examined cytogenetically. Six of 13 cases (46.0%) lacked the short arm of chromosome 1 through monosomy 1 or structural rearrangement of 1p. To date 29.0% of oncocytomas reported in the literature have shared this anomaly.3 When the current findings are added, the overall frequency of 1p abnormalities is 32.0%. Only the series of Fuzesi et al showed no abnormalities of 1p but this series is somewhat unique.7 Cumulative cytogenetic results as well as loss of heterozygosity studies10 and comparative genomic hybridization analyses11 indicate a tumor suppressor gene in
603
1p36. Loss of this putative gene appears to be the most common change in oncocytomas. Four of the 13 cases (31%) in our study had an apparently normal karyotype. However, the possibility of abnormalities below the resolution of cytogenetics cannot be ruled out. Identification of a tumor suppressor gene involved in oncocytomas would allow the testing of such cases. Several tumors in our study contained abnormal clones that were interpreted as culture related. Cells in patient 1 showed trisomy 18, cells in patients 6, 9 and 10 lacked the Y chromosome, and cells in patients 2 and 9 had trisomy 7. Numerical aberrations, including trisomy 5, 7, 8, 10 and 18, and Y loss, occur in normal kidney tissue.12, 13 Loss of the Y chromosome and trisomy 7 are especially common. They are often the first changes to appear and may be associated with genetic instability, leading to hyperplasia and dysplasia.13 However, additional studies are needed to address the issue of the potential significance of such changes in oncocytoma. No abnormalities involving chromosome 11 were detected in this series of 12 patients. Our findings are similar to those in the 5 cases described by Crotty et al4 and the 4 described by Dobin et al,5 in which no 11q13 anomalies were detected. In contrast, 1 of 9 tumors (11.0%) examined by van den Berg et al6 and 4 of 11 specimens (36.0%) in the series of Fuzesi et al7 had 11q13 structural rearrangements. The percent with 1p abnormalities in these studies was 33%6 and 0%,7 respectively. Reasons for differences in the frequency of chromosome 1 and 11 abnormalities among institutions and parts of the world are unclear. Oncocytic change may be seen in several kidney tumor types and, therefore, differences in diagnostic criteria may be responsible for at least some discrepancies.14 Regrettably most cytogenetic reports provide scant descriptions of how the diagnosis was made and whether the pathological diagnosis was corroborated by additional studies. We have observed translocation involving 11q13 only in a metastatic tumor with features of chromophobe renal cell carcinoma (Lindgren, Paner, Flanigan, Clark and Picken, unpublished data). The incidence of bilaterality and multifocality in oncocytomas is 5.0% and 6.0%, respectively.15 Familial cases of oncocytoma have been described and in the manner of heritable cancers they occur bilaterally, although to date no tumor related chromosome abnormalities have been found.16 Our patients 1, 2, 4 to 6 and 10 with bilateral or multiple oncocytoma appeared to have sporadic disease. Cytogenetic studies were performed on only 1 tumor in patients 1, 2 and 5, and in 2 in patients 6 and 10. In patient 6 the karyotypes were related with loss of the Y and monosomy 1 in the 2 tumors and the additional abnormality of monosomy 14 in the right tumor. Monosomy 14 has been found as a recurring abnormality in some oncocytomas.5 Comparative genomic hybridization
TABLE 2. Cytogenetic findings Pt No. 1 2 3 4 5 6 7
Site Rt ⫹ lt Rt ⫹ lt Rt Rt Lt site 1 Rt ⫹ lt Lt
8 Rt 9 Lt 10 Rt, lt sites 1 ⫹ 2 11 Rt 12 Lt Karyotypes considered tumor related are in bold.
Karyotypes 47,XY,⫹18[3]/46,XY[12]/nonclonal abnormality [5] ⫹ not sampled 43,X,ⴚY,ⴚ1,i(9)(p10),ⴚ21[9]/47,XY,⫹7[2]/46,XY[9] ⫹ not sampled 46,XY[20] No growth 46,XY[6]/nonclonal abnormality [1] 43,X,ⴚY,ⴚ1,ⴚ14[6]/45,X,⫺Y[4]/46,XY[8]/nonclonal abnormality [2] ⫹ 44,X,ⴚY,ⴚ1[20] 45,XX,der(1;13)(q10;q10),der(5)t(5;?21)(q11.2;?p13), der(8)t(8;17)(q21.2;q23),der(17)t(5;17)(q33; q23), der(21)t(5;21)(q11.2;p13),t(5;8)(q33;q21.1), t(15;19)(q15;p13.1)[15]/45,idem,t(4;6)(p1?6; q21)[2]/46,XX[3] 46,XX[19]/nonclonal abnormality [1] 45,X,⫺Y[3]/46,X,⫺Y,⫹7[2]/46,X,⫺Y,⫹14[1]/46,XY[14] Not sampled, 46,XY[18]/nonclonal abnormality [2] ⫹ 45,X,⫺Y[6]/46,XY[9]/nonclonal abnormality [5] 46,XX,der(1;5)(q10;p10),ⴙ5[15]/46,XX[5] 44,XX,ⴚ1,ⴚ14[20]
604
CYTOGENIC ANALYSIS OF RENAL ONCOCYTOMA
studies have also detected frequent loss of chromosome 14.11 In our view another case that was reported by Dal Cin et al as papillary neoplasm17 is more consistent with a diagnosis of oncocytic or chromophobe neoplasm based on the pattern of chromosomal abnormalities (42,X,⫺Y,⫺14,⫺15 in each kidney). Our case and that of Dal Cin et al lead us to speculate that an additional chromosomal abnormality (ie loss of chromosome 14) may be associated with the development of sporadic oncocytoma phenocopy in the opposite kidney.17 The tumor in patient 2 demonstrated chromosome 21 loss and an isochromosome 9p with 9q loss. It has been proposed that multiple chromosomal losses, including that of chromosome 21, from oncocytoma may result in progression to a chromophobe carcinoma. However, histologically this oncocytoma did not show morphological transition toward chromophobe carcinoma. Of note is the relatively large size of this tumor (12.2 cm). Except for the case of Dal Cin et al17 we were able to find only 1 other nonfamilial case in which tumors from the 2 kidneys were examined cytogenetically.18 Karyotypes are not completely specified but each kidney showed multiple clones with abnormalities, including loss of the X chromosome, trisomy 7, monosomy 3 and monosomy 14, of which some are also seen in normal kidney. Clearly a problem with interpreting cytogenetic findings in oncocytoma is the occurrence of changes that are also seen in normal tissue. As suggested by Tickoo et al,8 the term oncocytosis indicates innumerable oncocytic nodules in the kidney. We observed this morphological pattern in patient 10 of our series. The samples obtained from the 2 main oncocytomas in the left kidney had a normal karyotype with loss of the Y chromosome in some cells of 1 tumor, which is a common aberration in a normal kidney. In the only other case of oncocytosis with cytogenetic study the karyotypes of the 2 main oncocytomas were also normal.19 Several lines of evidence suggest that benign oncocytomas and malignant chromophobe renal carcinoma cells are related.13, 20 The 2 tumors have alterations in mitochondrial DNA. Their genetic changes also appear to overlap with chromophobe tumors evidencing multiple monosomies of 1, 2, 6, 10, 13, 17, 21 and the X or Y. It has been proposed that oncocytomas should be considered chromophobe adenomas, which may evolve into chromophobe renal cell carcinoma.13, 20 In our series we noted the focal presence of chromophobe-like cells in patients 5 and 9, which we classified as hybrid tumors. Neither case showed multiple monosomies, 1 had a normal karyotype and 1 had a clone with Y loss. However, if chromophobe-like changes are truly focal, sampling error may be responsible for apparent karyotypic normalcy. CONCLUSIONS
Further cytogenetic studies are required to delineate the differences between oncocytoma and chromophobe carcinoma. Genetic studies are also necessary to identify and characterize the putative tumor suppressor on chromosome 1p that may be involved in the generation of oncocytoma. REFERENCES
1. Amin, M. B., Crotty, T. B., Tickoo, S. K. and Farrow, G. M.: Renal oncocytoma: a reappraisal of morphologic features with clinicopathologic findings in 80 cases. Am J Surg Pathol, 21: 1, 1997 2. Kovacs, G., Akhtar, M., Beckwith, B. J., Bugert, P., Cooper, C. S., Delahunt, B. et al: The Heidelberg classification of renal cell
tumours. J Pathol, 183: 131, 1997 3. Mitelman, F., Johansson, B. and Mertens, F.: Mitelman database of chromosome aberrations in cancer (2003). Available at http://cgap.nci.nih.gov/Chromosomes/Mitelman. Accessed April 21, 2003 4. Crotty, T. B., Lawrence, K. M., Moertel, C. A., Bartelt, D. H., Jr., Batts, K. P., Dewald, G. W. et al: Cytogenetic analysis of six renal oncocytomas and a chromophobe cell renal carcinoma. Evidence that ⫺Y, ⫺1 may be a characteristic anomaly in renal oncocytomas. Cancer Genet Cytogenet, 61: 61, 1992 5. Dobin, S. M., Harris, C. P., Reynolds, J. A., Coffield, K. S., Klugo, R. C., Peterson, R. F. et al: Cytogenetic abnormalities in renal oncocytic neoplasms. Genes Chromosomes Cancer, 4: 25, 1992 6. van den Berg, E., Dijkhuizen, T., Storkel, S., de la Riviere, G. B., Dam, A., Mensink, H. J. et al: Chromosomal changes in renal oncocytomas. Evidence that t(5;11)(q35;q13) may characterize a second subgroup of oncocytomas. Cancer Genet Cytogenet, 79: 164, 1995 7. Fuzesi, L., Gunawan, B., Braun, S., Bergmann, F., Brauers, A., Effert, P. et al: Cytogenetic analysis of 11 renal oncocytomas: further evidence of structural rearrangements of 11q13 as a characteristic chromosomal anomaly. Cancer Genet Cytogenet, 107: 1, 1998 8. Tickoo, S. K., Reuter, V. E., Amin, M. B., Srigley, J. R., Epstein, J. I., Min, K. W. et al: Renal oncocytosis: a morphologic study of fourteen cases. Am J Surg Pathol, 23: 1094, 1999 9. Picken, M. M., Curry, J. L., Lindgren, V., Clark, J. I. and Eble, J. N.: Metanephric adenosarcoma in a young adult: morphologic, immunophenotypic, ultrastructural, and fluorescence in situ hybridization analyses: a case report and review of the literature. Am J Surg Pathol, 25: 1451, 2001 10. Thrash-Bingham, C. A., Salazar, H., Greenberg, R. E. and Tartof, K. D.: Loss of heterozygosity studies indicate that chromosome arm 1p harbors a tumor suppressor gene for renal oncocytomas. Genes Chromosomes Cancer, 16: 64, 1996 11. Presti, J. C., Jr., Moch, H., Reuter, V. E., Huynh, D. and Waldman, F. M.: Comparative genomic hybridization for genetic analysis of renal oncocytomas. Genes Chromosomes Cancer, 17: 199, 1996 12. van den Berg, E., Dijkhuizen, T., Storkel, S., Molenaar, W. M. and de Jong, B.: Chromosomal abnormalities in non-neoplastic renal tissue. Cancer Genet Cytogenet, 85: 152, 1995 13. van den Berg, E., Dijkhuizen, T., Oosterhuis, J. W., Guerts van Kessel, A., de Jong, B. and Storkel, S.: Cytogenetic classification of renal cell cancer. Cancer Genet Cytogenet, 95: 103, 1997 14. Reuter, V. E.: Renal tumors exhibiting granular cytoplasm. Semin Diagn Pathol, 16: 135, 1999 15. Dechet, C. B., Bostwick, D. G., Blute, M. L., Bryant, S. C. and Zincke, H.: Renal oncocytoma: multifocality, bilateralism, metachronous tumor development and coexistent renal cell carcinoma. J Urol, 162: 40, 1999 16. Khoo, S. K., Bradley, M., Wong, F. K., Hedblad, M. A., Nordenskjold, M. and Teh, B. T.: Birt-Hogg-Dube syndrome: mapping of a novel hereditary neoplasia gene to chromosome 17p12– q11.2. Oncogene, 20: 5239, 2001 17. Dal Cin, P., Van Poppel, H., Van Damme, B., Baert, L. and Van den Berghe, H.: Cytogenetic investigation of synchronous bilateral renal tumors. Cancer Genet Cytogenet, 89: 57, 1996 18. Psihramis, K. E., Althausen, A. F., Yoshida, M. A., Prout, G. R., Jr. and Sandberg, A. A.: Chromosome anomalies suggestive of malignant transformation in bilateral renal oncocytoma. J Urol, 136: 892, 1986 19. Leroy, X., Lemaitre, L., De La Taille, A., Hazzan, M., Delepaul, B., Couturier, J. et al: Bilateral renal oncocytosis with renal failure. Arch Pathol Lab Med, 125: 683, 2001 20. Dijkhuizen, T., van den Berg, E., Storkel, S., de Vries, B., van der Veen, A. Y., Wilbrink, M. et al: Renal oncocytoma with t(5;12; 11), der(1)1;8) and add (19): “true” oncocytoma or chromophobe adenoma? Int J Cancer, 73: 521, 1997
Vol. 171, 602– 604, February 2004 Printed in U.S.A.
DOI: 10.1097/01.ju.0000109172.07081.16
CYTOGENETIC ANALYSIS OF A SERIES OF 13 RENAL ONCOCYTOMAS VALERIE LINDGREN,* GLADELL P. PANER, ATILLA OMEROGLU, STEVEN C. CAMPBELL,† W. BEDFORD WATERS, ROBERT C. FLANIGAN AND MARIA M. PICKEN From the Department of Pathology, University of Illinois at Chicago (VL), Chicago and Departments of Pathology (GPP, AO, MMP) and Urology (SCC, WBW, RCF), Loyola University of Chicago, Maywood, Illinois
ABSTRACT
Purpose: Only about 50 renal oncocytomas have been studied cytogenetically. They fall into 3 categories, namely 1—normal karyotype, 2—monosomy 1, often with Y chromosome loss, and 3—structural abnormalities of 11q13. Additional abnormalities may occur with transformation to chromophobe renal cell carcinoma, although exactly which one is unclear. We expanded the oncocytoma data base to shed light on changes that characterize transformation. Materials and Methods: A total of 14 oncocytomas from 12 patients were collected in 21⁄2 years. One tumor failed to grow but 13 were successfully karyotyped. Results: Seven tumors (53.8%), including 2 from 1 kidney, had normal karyotypes or abnormalities characteristic of normal kidney tissue. A total of 6 tumors from 5 individuals (46.2%) had chromosome 1 abnormalities. Monosomy 1 was detected in 2 single tumors and in both tumors in a bilateral case. Structural anomalies resulting in loss of the short arm of chromosome 1 were found in an additional 2 patients. Other abnormalities, including Y chromosome loss and monosomy 14, were observed but no abnormalities of 11q13 were seen. Conclusions: Our series confirms that 1p loss is the most common anomaly in oncocytoma. Additional studies are required to understand the transformation potential of this usually benign tumor, identify the putative 1p tumor suppressor gene and determine whether karyotypically normal tumors have molecular abnormalities of 1p. KEY WORDS: kidney; adenoma, oxyphilic; carcinoma, renal cell; chromosome aberrations; genes, tumor suppressor
Approximately 3.0% to 5.0%1 of renal tumors are classified histologically as oncocytoma, a typically benign epithelial tumor characterized by eosinophilic cytoplasm containing abundant mitochondria. The current diagnostic criteria for kidney tumors are largely based on (cyto)genetic abnormalities specific to each tumor class.2 However, according to the 2003 Mitelman et al data base of chromosome abnormalities in cancer only slightly more than 50 oncocytomas have been cytogenetically analyzed to date.3 Moreover, when morphological or genetic criteria are the basis for classification, gray areas arise in distinguishing oncocytoma and chromophobe renal cell carcinoma. Furthermore, to our knowledge no genes involved in the genesis of oncocytoma have been clearly identified. Karyotypes in oncocytomas fall into 3 categories, namely 1—normal, 2—loss of chromosome 1 or the short arm of chromosome 1, loss of the Y chromosome and occasionally monosomy 14, and 3—structural rearrangements involving chromosome 11 band q13.3–7 The majority of cytogenetic reports include a single oncocytoma. Only 4 small series of oncocytomas have been published that include more than 2 tumors.4 –7 Since most publications included only cases of abnormal karyotypes, the percent of tumors in the different cytogenetic categories is unclear. Furthermore, the clinical significance of each karyotype is unresolved. We analyzed cytogenetically a series of morphologically well characterized oncocytomas.
MATERIALS AND METHODS
Of 133 kidneys surgically removed by partial or radical nephrectomy at Loyola University Medical Center from August 1998 to February 2001, 16 (12.0%) from 12 patients contained renal oncocytoma. Fresh specimens for cytogenetic analysis were available in 14 oncocytomas from these patients. The diagnosis of oncocytoma was based on previously published criteria.1, 8 Immunohistochemistry, colloidal iron staining and electron microscopy studies confirmed the diagnosis. Immunohistochemical stains included pankeratin, cytokeratin 7 and vimentin. Electron microscopic studies were performed as previously described.9 For cytogenetic analysis fresh samples from each tumor were disaggregated with collagenase, physically disrupted and put into culture for 1 to 10 days with Eagle’s minimal essential medium. Harvesting and staining followed standard cytogenetic techniques. When possible, 20 cells per tumor were examined. RESULTS
The 12 patients in this series included 7 males and 5 females 42 to 84 years old (median age 69). Table 1 lists patient clinicopathological features. Masses were bilateral in 4 of 12 patients. All bilateral oncocytomas occurred synchronously. Multifocality within a single kidney was observed in patients 5 and 10. Thus, 5 of 12 patients (42.0%) had more than 1 synchronous oncocytoma. In patient 10 in addition to oncocytomas, there were multiple microscopic oncocytic nodules in each kidney (oncocytosis). Oncocytomas in 10 of the 12 patients (83.3%) demonstrated a pure histology. In patients 5 and 9 there were focal areas (approximately 25%) of cells with cytoplasmic membrane condensation and prominent perinuclear clearing (chromophobe-like cells) in a background of classic oncocytic cells. These 2 tumors showed focal reticular cytoplasmic staining with Hale’s colloidal
Accepted for publication September 19, 2003. Study received institutional review board approval. * Correspondence: Department of Pathology (MC 750), University of Illinois Medical Center at Chicago, Building 911, Room 211A, 840 S Wood St., Chicago, Illinois 60612 (telephone: 312-355-3619; FAX: 312-413-0156; e-mail: [email protected]). † Financial interest and/or other relationship with Novartis and Aventis. 602
CYTOGENIC ANALYSIS OF RENAL ONCOCYTOMA TABLE 1. Clinicopathological summary of oncocytoma No. pts 12 No. involvement: Unilat 8 Bilat 4 Dominant tumor nodule size (cm) 1.0–12.2 No. histological morphology:* Pure oncocytoma 12 Hybrid oncocytoma with focal chromophobe 2 Ca features Oncocytoma with oncocytosis 2 No. nephrectomy:* Partial 5 Radical 11 * Bilateral tumors in 4 patients, or a total of 16 oncocytomas.
iron and focal positivity for cytokeratin 7. However, all other cases were negative for these stains. Other stains showed positivity for pankeratin (16 of 16 tumors) and negativity for vimentin (16 of 16 tumors). Electron microscopic studies were performed on 13 tumors and all had abundant mitochondria. In patient 6 solitary tumors (1 per kidney) were noted. In patient 10, 2 tumors from the same kidney were studied. In all other cases a single tumor was submitted even when there were multiple tumors. One specimen in patient 4 failed to grow but results were obtained from 13 tumors (table 2). A total of 7 tumors from patients 1, 3, 5 and 8 to 10 demonstrated only normal cells, nonclonal abnormalities or cells with trisomy 7 and/or a lack of the Y. Trisomy 18 was detected in patient 1 but only in a minority of cells. The 6 remaining tumors from 5 patients had abnormalities of chromosome 1, including monosomy 1 in a total of 4 tumors in patients 2, 6 and 12, and structural abnormalities resulting in loss of the whole short arm of chromosome 1 in 2 tumors in patients 7 and 11, respectively. The tumor in patient 7 had multiple, complex structural abnormalities but without apparent loss of material except of 1p. Two tumors in the right kidney of patients 6 and 12, respectively, had monosomy 14 in addition to monosomy 1. Patient 2 lacked chromosome 21 and had an isochromosome for 9p with concomitant 9q loss. DISCUSSION
In our series of 14 pathologically well-defined oncocytomas 13 were successfully examined cytogenetically. Six of 13 cases (46.0%) lacked the short arm of chromosome 1 through monosomy 1 or structural rearrangement of 1p. To date 29.0% of oncocytomas reported in the literature have shared this anomaly.3 When the current findings are added, the overall frequency of 1p abnormalities is 32.0%. Only the series of Fuzesi et al showed no abnormalities of 1p but this series is somewhat unique.7 Cumulative cytogenetic results as well as loss of heterozygosity studies10 and comparative genomic hybridization analyses11 indicate a tumor suppressor gene in
603
1p36. Loss of this putative gene appears to be the most common change in oncocytomas. Four of the 13 cases (31%) in our study had an apparently normal karyotype. However, the possibility of abnormalities below the resolution of cytogenetics cannot be ruled out. Identification of a tumor suppressor gene involved in oncocytomas would allow the testing of such cases. Several tumors in our study contained abnormal clones that were interpreted as culture related. Cells in patient 1 showed trisomy 18, cells in patients 6, 9 and 10 lacked the Y chromosome, and cells in patients 2 and 9 had trisomy 7. Numerical aberrations, including trisomy 5, 7, 8, 10 and 18, and Y loss, occur in normal kidney tissue.12, 13 Loss of the Y chromosome and trisomy 7 are especially common. They are often the first changes to appear and may be associated with genetic instability, leading to hyperplasia and dysplasia.13 However, additional studies are needed to address the issue of the potential significance of such changes in oncocytoma. No abnormalities involving chromosome 11 were detected in this series of 12 patients. Our findings are similar to those in the 5 cases described by Crotty et al4 and the 4 described by Dobin et al,5 in which no 11q13 anomalies were detected. In contrast, 1 of 9 tumors (11.0%) examined by van den Berg et al6 and 4 of 11 specimens (36.0%) in the series of Fuzesi et al7 had 11q13 structural rearrangements. The percent with 1p abnormalities in these studies was 33%6 and 0%,7 respectively. Reasons for differences in the frequency of chromosome 1 and 11 abnormalities among institutions and parts of the world are unclear. Oncocytic change may be seen in several kidney tumor types and, therefore, differences in diagnostic criteria may be responsible for at least some discrepancies.14 Regrettably most cytogenetic reports provide scant descriptions of how the diagnosis was made and whether the pathological diagnosis was corroborated by additional studies. We have observed translocation involving 11q13 only in a metastatic tumor with features of chromophobe renal cell carcinoma (Lindgren, Paner, Flanigan, Clark and Picken, unpublished data). The incidence of bilaterality and multifocality in oncocytomas is 5.0% and 6.0%, respectively.15 Familial cases of oncocytoma have been described and in the manner of heritable cancers they occur bilaterally, although to date no tumor related chromosome abnormalities have been found.16 Our patients 1, 2, 4 to 6 and 10 with bilateral or multiple oncocytoma appeared to have sporadic disease. Cytogenetic studies were performed on only 1 tumor in patients 1, 2 and 5, and in 2 in patients 6 and 10. In patient 6 the karyotypes were related with loss of the Y and monosomy 1 in the 2 tumors and the additional abnormality of monosomy 14 in the right tumor. Monosomy 14 has been found as a recurring abnormality in some oncocytomas.5 Comparative genomic hybridization
TABLE 2. Cytogenetic findings Pt No. 1 2 3 4 5 6 7
Site Rt ⫹ lt Rt ⫹ lt Rt Rt Lt site 1 Rt ⫹ lt Lt
8 Rt 9 Lt 10 Rt, lt sites 1 ⫹ 2 11 Rt 12 Lt Karyotypes considered tumor related are in bold.
Karyotypes 47,XY,⫹18[3]/46,XY[12]/nonclonal abnormality [5] ⫹ not sampled 43,X,ⴚY,ⴚ1,i(9)(p10),ⴚ21[9]/47,XY,⫹7[2]/46,XY[9] ⫹ not sampled 46,XY[20] No growth 46,XY[6]/nonclonal abnormality [1] 43,X,ⴚY,ⴚ1,ⴚ14[6]/45,X,⫺Y[4]/46,XY[8]/nonclonal abnormality [2] ⫹ 44,X,ⴚY,ⴚ1[20] 45,XX,der(1;13)(q10;q10),der(5)t(5;?21)(q11.2;?p13), der(8)t(8;17)(q21.2;q23),der(17)t(5;17)(q33; q23), der(21)t(5;21)(q11.2;p13),t(5;8)(q33;q21.1), t(15;19)(q15;p13.1)[15]/45,idem,t(4;6)(p1?6; q21)[2]/46,XX[3] 46,XX[19]/nonclonal abnormality [1] 45,X,⫺Y[3]/46,X,⫺Y,⫹7[2]/46,X,⫺Y,⫹14[1]/46,XY[14] Not sampled, 46,XY[18]/nonclonal abnormality [2] ⫹ 45,X,⫺Y[6]/46,XY[9]/nonclonal abnormality [5] 46,XX,der(1;5)(q10;p10),ⴙ5[15]/46,XX[5] 44,XX,ⴚ1,ⴚ14[20]
604
CYTOGENIC ANALYSIS OF RENAL ONCOCYTOMA
studies have also detected frequent loss of chromosome 14.11 In our view another case that was reported by Dal Cin et al as papillary neoplasm17 is more consistent with a diagnosis of oncocytic or chromophobe neoplasm based on the pattern of chromosomal abnormalities (42,X,⫺Y,⫺14,⫺15 in each kidney). Our case and that of Dal Cin et al lead us to speculate that an additional chromosomal abnormality (ie loss of chromosome 14) may be associated with the development of sporadic oncocytoma phenocopy in the opposite kidney.17 The tumor in patient 2 demonstrated chromosome 21 loss and an isochromosome 9p with 9q loss. It has been proposed that multiple chromosomal losses, including that of chromosome 21, from oncocytoma may result in progression to a chromophobe carcinoma. However, histologically this oncocytoma did not show morphological transition toward chromophobe carcinoma. Of note is the relatively large size of this tumor (12.2 cm). Except for the case of Dal Cin et al17 we were able to find only 1 other nonfamilial case in which tumors from the 2 kidneys were examined cytogenetically.18 Karyotypes are not completely specified but each kidney showed multiple clones with abnormalities, including loss of the X chromosome, trisomy 7, monosomy 3 and monosomy 14, of which some are also seen in normal kidney. Clearly a problem with interpreting cytogenetic findings in oncocytoma is the occurrence of changes that are also seen in normal tissue. As suggested by Tickoo et al,8 the term oncocytosis indicates innumerable oncocytic nodules in the kidney. We observed this morphological pattern in patient 10 of our series. The samples obtained from the 2 main oncocytomas in the left kidney had a normal karyotype with loss of the Y chromosome in some cells of 1 tumor, which is a common aberration in a normal kidney. In the only other case of oncocytosis with cytogenetic study the karyotypes of the 2 main oncocytomas were also normal.19 Several lines of evidence suggest that benign oncocytomas and malignant chromophobe renal carcinoma cells are related.13, 20 The 2 tumors have alterations in mitochondrial DNA. Their genetic changes also appear to overlap with chromophobe tumors evidencing multiple monosomies of 1, 2, 6, 10, 13, 17, 21 and the X or Y. It has been proposed that oncocytomas should be considered chromophobe adenomas, which may evolve into chromophobe renal cell carcinoma.13, 20 In our series we noted the focal presence of chromophobe-like cells in patients 5 and 9, which we classified as hybrid tumors. Neither case showed multiple monosomies, 1 had a normal karyotype and 1 had a clone with Y loss. However, if chromophobe-like changes are truly focal, sampling error may be responsible for apparent karyotypic normalcy. CONCLUSIONS
Further cytogenetic studies are required to delineate the differences between oncocytoma and chromophobe carcinoma. Genetic studies are also necessary to identify and characterize the putative tumor suppressor on chromosome 1p that may be involved in the generation of oncocytoma. REFERENCES
1. Amin, M. B., Crotty, T. B., Tickoo, S. K. and Farrow, G. M.: Renal oncocytoma: a reappraisal of morphologic features with clinicopathologic findings in 80 cases. Am J Surg Pathol, 21: 1, 1997 2. Kovacs, G., Akhtar, M., Beckwith, B. J., Bugert, P., Cooper, C. S., Delahunt, B. et al: The Heidelberg classification of renal cell
tumours. J Pathol, 183: 131, 1997 3. Mitelman, F., Johansson, B. and Mertens, F.: Mitelman database of chromosome aberrations in cancer (2003). Available at http://cgap.nci.nih.gov/Chromosomes/Mitelman. Accessed April 21, 2003 4. Crotty, T. B., Lawrence, K. M., Moertel, C. A., Bartelt, D. H., Jr., Batts, K. P., Dewald, G. W. et al: Cytogenetic analysis of six renal oncocytomas and a chromophobe cell renal carcinoma. Evidence that ⫺Y, ⫺1 may be a characteristic anomaly in renal oncocytomas. Cancer Genet Cytogenet, 61: 61, 1992 5. Dobin, S. M., Harris, C. P., Reynolds, J. A., Coffield, K. S., Klugo, R. C., Peterson, R. F. et al: Cytogenetic abnormalities in renal oncocytic neoplasms. Genes Chromosomes Cancer, 4: 25, 1992 6. van den Berg, E., Dijkhuizen, T., Storkel, S., de la Riviere, G. B., Dam, A., Mensink, H. J. et al: Chromosomal changes in renal oncocytomas. Evidence that t(5;11)(q35;q13) may characterize a second subgroup of oncocytomas. Cancer Genet Cytogenet, 79: 164, 1995 7. Fuzesi, L., Gunawan, B., Braun, S., Bergmann, F., Brauers, A., Effert, P. et al: Cytogenetic analysis of 11 renal oncocytomas: further evidence of structural rearrangements of 11q13 as a characteristic chromosomal anomaly. Cancer Genet Cytogenet, 107: 1, 1998 8. Tickoo, S. K., Reuter, V. E., Amin, M. B., Srigley, J. R., Epstein, J. I., Min, K. W. et al: Renal oncocytosis: a morphologic study of fourteen cases. Am J Surg Pathol, 23: 1094, 1999 9. Picken, M. M., Curry, J. L., Lindgren, V., Clark, J. I. and Eble, J. N.: Metanephric adenosarcoma in a young adult: morphologic, immunophenotypic, ultrastructural, and fluorescence in situ hybridization analyses: a case report and review of the literature. Am J Surg Pathol, 25: 1451, 2001 10. Thrash-Bingham, C. A., Salazar, H., Greenberg, R. E. and Tartof, K. D.: Loss of heterozygosity studies indicate that chromosome arm 1p harbors a tumor suppressor gene for renal oncocytomas. Genes Chromosomes Cancer, 16: 64, 1996 11. Presti, J. C., Jr., Moch, H., Reuter, V. E., Huynh, D. and Waldman, F. M.: Comparative genomic hybridization for genetic analysis of renal oncocytomas. Genes Chromosomes Cancer, 17: 199, 1996 12. van den Berg, E., Dijkhuizen, T., Storkel, S., Molenaar, W. M. and de Jong, B.: Chromosomal abnormalities in non-neoplastic renal tissue. Cancer Genet Cytogenet, 85: 152, 1995 13. van den Berg, E., Dijkhuizen, T., Oosterhuis, J. W., Guerts van Kessel, A., de Jong, B. and Storkel, S.: Cytogenetic classification of renal cell cancer. Cancer Genet Cytogenet, 95: 103, 1997 14. Reuter, V. E.: Renal tumors exhibiting granular cytoplasm. Semin Diagn Pathol, 16: 135, 1999 15. Dechet, C. B., Bostwick, D. G., Blute, M. L., Bryant, S. C. and Zincke, H.: Renal oncocytoma: multifocality, bilateralism, metachronous tumor development and coexistent renal cell carcinoma. J Urol, 162: 40, 1999 16. Khoo, S. K., Bradley, M., Wong, F. K., Hedblad, M. A., Nordenskjold, M. and Teh, B. T.: Birt-Hogg-Dube syndrome: mapping of a novel hereditary neoplasia gene to chromosome 17p12– q11.2. Oncogene, 20: 5239, 2001 17. Dal Cin, P., Van Poppel, H., Van Damme, B., Baert, L. and Van den Berghe, H.: Cytogenetic investigation of synchronous bilateral renal tumors. Cancer Genet Cytogenet, 89: 57, 1996 18. Psihramis, K. E., Althausen, A. F., Yoshida, M. A., Prout, G. R., Jr. and Sandberg, A. A.: Chromosome anomalies suggestive of malignant transformation in bilateral renal oncocytoma. J Urol, 136: 892, 1986 19. Leroy, X., Lemaitre, L., De La Taille, A., Hazzan, M., Delepaul, B., Couturier, J. et al: Bilateral renal oncocytosis with renal failure. Arch Pathol Lab Med, 125: 683, 2001 20. Dijkhuizen, T., van den Berg, E., Storkel, S., de Vries, B., van der Veen, A. Y., Wilbrink, M. et al: Renal oncocytoma with t(5;12; 11), der(1)1;8) and add (19): “true” oncocytoma or chromophobe adenoma? Int J Cancer, 73: 521, 1997