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Pathology and Molecular Pathogenesis of Renal Cell Carcinoma
european urology supplements 5 (2006) 573–579
available at www.sciencedirect.com journal homepage: www.europeanurology.com
Pathology and Molecular Pathogenesis of Renal Cell Carcinoma Barbara Corti a, Nicola Zucchini a, Benedetta Fabbrizio a, Giuseppe Martorana b, Riccardo Schiavina b, Antonia D’Errico Grigioni a, Walter Franco Grigioni a,* a
Pathology Division, F. Addarii Institute of Oncology, Department of Oncology and Haematology, S. Orsola–Malpighi Hospital, University of Bologna, Bologna, Italy b Department of Urology, University of Bologna, Bologna, Italy
Article info
Abstract
Keywords: Grade Molecular pathogenesis Pathology Prognosis Renal cell carcinoma Stage
Objectives: In this review, we summarise the World Health Organization (WHO) classification of renal cell carcinomas (RCCs) alongside grading and staging systems. General applications of immunohistochemistry, cytogenetics, and cDNA microarrays were reviewed with their implications in tumour diagnosis, prognosis, and therapy. Results: RCCs are classified according to the 2004 WHO classification, which defines three main histopathologic tumour subtypes with distinct clinical behaviour and underlying genetic defects: conventional (clear cell), papillary, and chromophobe RCC. Histopathologic classification and specific genetic mutations are crucial in distinguishing between familial and nonfamilial tumours. The most common four-tiered Fuhrman nuclear grade system is recommended for all types of RCC. Tumour grade is assigned according to the highest grade present; staging is assigned using the Union Internationale Contre le Cancer/American Joint Committee on Cancer 2002 classification. Conclusions: Prognosis of patients with RCCs is most accurately predicted by TNM stage. Within stages, Fuhrman grade has a strong predictive value. Although not considered in nuclear grading, sarcomatoid dedifferentiation is a severely negative event for all RCC subtypes. Histologic subtypes of RCCs are not independent prognostic factors comparable with TNM stage and Fuhrman grade. Histologic coagulative tumour necrosis was an independent prognostic factor of outcome for clear cell and chromophobe RCC. Immunohistochemical panels including RCC marker, CD10, and KIT are now available for differential diagnosis of the distinct RCC subtypes. Genetic studies have improved understanding of subtypes, offering a promising approach for clinical diagnosis, prognosis, and possibly therapy. Urologists should be aware that currently many molecular analyses can be performed on RCCs, and when feasible, fresh samples sent to the pathologist. # 2006 European Association of Urology. Published by Elsevier B.V. All rights reserved.
* Corresponding author. Istituto F. Addarii, Policlinico S. Orsola Malpighi, Viale ercolani 4/2, 40138, Bologna, Italy. Tel. +39 0516364546; Fax: +39 0516354403. E-mail address: [email protected] (W.F. Grigioni). 1569-9056/$ – see front matter # 2006 European Association of Urology. Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.eursup.2006.03.005
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european urology supplements 5 (2006) 573–579
Table 2 – Genetic defects in nonfamilial renal cell carcinoma
Introduction
Renal cell carcinomas (RCCs) arise from the renal epithelium and account for >90% of all renal malignancies occurring in adult men and women. About 2% of RCCs are associated with inherited syndromes; specific oncogenes or tumour suppressor genes and their mutations have been identified for most of these (Table 1). Distinct genetic defects have also been described in nonfamilial RCC (Table 2). The Heidelberg classification, which was introduced in 1997 [1], described the identified genetic defects of both sporadic and familial RCC in relation to histopathologic appearance. The 2004 World Health Organization (WHO) classification [2] distinguishes three main histologic subtypes: conventional (clear cell), papillary, and chromophobe RCC. Rarer subtypes include carcinoma of the collecting duct of Bellini and new diagnostic categories as medullary carcinoma, Xp11 carcinoma, carcinoma associated with neuroblastoma (in long-term survivors of childood neuroblastoma), and mucinous tubular and spindle cell carcinoma. In a recent paper [3], these rare new entities have been duly revised, confirming that recognition of these tumours may have important implications for the patient’s management. Additionally, ‘‘RCC, unclassified’’ was introduced as a novel diagnostic category to accommodate tumours that do not fit into any of the other morphologic categories. Representative examples of clear cell, papillary, and chromophobe RCC are shown in Fig. 1.
2.
Clear cell RCC
Histotype
Alterations
3 7 and 17 1, 2, 6, 10, 13, 17, 21
Deletions, mutations Trisomy and tetrasomy Chromosomal loss
CCRCC PRCC Chromophobe RCC
CCRCC = clear cell renal cell carcinoma; PRCC = papillary renal cell carcinoma.
tricity or bilaterality and early stage at the diagnosis are typical of inherited syndromes such as von Hippel-Lindau syndrome. Macroscopically, clear cell RCCs are round tumours that bulge out of the renal cortex. They are usually clearly demarcated from the adjacent renal parenchyma with a ‘‘pushing’’ border. All clear cell RCCs have a characteristic golden yellow appearance due to the rich lipid content of their cells. Cysts, hemorrhages, and calcifications are commonly encoutered. Tumour necrosis can also be present and should be routinely reported because it is a useful predictor of clinical outcome [4]. Microscopically, clear cell RCCs can present alveolar, acinar, or solid architectural patterns. A delicate vascular network of thin blood vessels is usually present. The cytoplasm of the neoplastic cells is usually clear, due to its lipid and glycogen content. A variable component of eosinophilic cells may be present. Nuclei are round to polygonal with indistinct nucleoli and finely distributed chromatin. Nuclear pleomorphism, prominent nucleoli, and coarse chromatin are typical features of high-grade tumours. 2.1.
Clear cell RCC, which is the most common histologic variant, is a malignant tumour composed of cells with clear or eosinophilic cytoplasm. It usually presents as a solitary cortical tumour, and it occurs with equal frequency in either kidney. Multicen-
Chromosomes
Immunoprofile
Clear cell RCCs commonly react with epithelial membrane antigen (EMA), low-molecular-weight cytokeratins (CK8, CK18, CK19), AE1, Cam 5.2, and vimentin. High-molecular-weight cytokeratins are rarely detected. MUC-1 and MUC-3 are consistently
Table 1 – Inherited renal cell carcinoma syndromes and related genetics defects Syndrome
Gene
Chromosome alterations
Pathologic appearence
von Hoppel-Lindau
VHL
3p25 loss of function mutations
Hereditary papillary renal carcinoma (HPRC) Hereditary leiomyomatosis and RCC Birt-Hogg-Dube`
MET
7q31 activating mutations
Multiple, bilateral CCRCC, phaeochromocytoma, CNS haemangioblastomas Multiple, bilateral PRCC, type 1
FH
1q42-43 inactivating mutations
BDH
17p11.2 inactivating mutations
Familial clear cell renal cancer (FCCRC)
3p translocations
Papillary renal cell carcinoma, non-type 1, cutaneous and uterine leiomyomas Multiple chromophobe and clear cell RCC and oncocytomas, skin tumours Multiple, bilateral CCRCC
CCRCC = clear cell renal cell carcinoma; CNS = central nervous system; PRCC = papillary renal cell carcinoma.
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Fig. 1 – Representative examples of clear cell (A), papillary (B), and chromophobe renal cell carcinoma (C). All tumours exhibit low-grade nuclei. Haematoxylin and eosin, 20.
expressed. b-Defensin-1 and parvalbumin are usually absent. Most clear cell RCCs react with RCC marker and CD10, which are useful for distinguishing the clear cell and chromophobe subtypes (see below). Of note, many clear cell RCCs react to placental alkaline phosphatase (PLAP) [5]. 2.2.
Genetics
Clear cell RCC can be a manifestation of von HippelLindau disease in association with mutiple extrarenal tumours, but it may also arise in other familial RCC syndromes (Table 1). All the inherited clear cell RCCs display VHL gene defects. The VHL gene is also involved in the majority of sporadic clear cell RCCs. In both istances, RCCs are characterised by late onset, unlike RCCs associated with Xp11.2 translocations, which predominantly affect children and young adults, although data on a few older patients have been reported [2]. Defects in the VHL gene arise
from allelic deletion, mutation, or epigenetic silencing in 60% of cases, making the VHL gene the major tumour suppressor gene in sporadic clear cell RCC. The inactivation of the VHL gene has effects on the VHL protein-regulated pathways. Normally, the VHL protein negatively regulates the transcriptional activators hypoxia-inducible factor (HIF) 1a and 2a, which activates genes involved in cell proliferation, angiogenesis, and extracellular matrix formation. Additional tumour suppressor genes associated with inherited and sporadic clear cell RCCs are also found on chromosome 3 [6]. Clonal accumulation of genetic abnormalites on many other chromosomoses then supervenes during clear cell RCC progression and metastasis [7,8]. Expression levels of a wide variety of genes have been investigated, including p53 and p27. The role of p53 overexpression in clear cell RCC is still debated; only a few studies recorded an association with poor prognosis [9,10]. Expression of p27 has been recently investi-
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gated in RCCs [11,12]. In clear cell RCCs, significant associations have been noted between decreased p27 levels and increasing tumour size and Fuhrman grade. However, no correlation has been found between decreased p27 levels and survival. Many studies suggest that high levels of vascular endothelial growth factor (VEGF) and E-cadherin may play a role in rapidity of tumour cell proliferation and progression [13–15]. Clear cell RCCs rarely exhibit high levels of gene amplifications. In particular, amplification of the EGFR gene is very uncommon and HER2/neu amplifications are rare or absent [16,17]. cDNA microarrays seem to provide new prognostic algorithms for clear cell RCCs, as recently reported [18]. 2.3.
Multilocular cystic RCC
About 5% of clear cell RCCs are predominantly cystic. These so-called cystic or multilocular cystic RCCs are thought to be subtypes of clear cell RCCs. The tumours are composed of noncomunicating cysts separated by thick fibrotic septa that resemble a multilocular cyst. The correct diagnosis is made on detection of small groups of low-grade clear cells in the walls of the cysts. Usually, the epithelium lining the cysts is attenuated or absent. The septa may be calcified (only rarely with ossification). Multilocular cystic RCCs have to be distinguished from clear cell RCCs exhibiting cystic changes; the latter commonly display expansile solid nodules of clear cells in their cystic walls or papillary projections lined by clear cells. Recognition of multilocular cystic RCC is extremely important because of its favourable clinical behaviour. In fact, no tumour with features of multilocular cystic RCC has ever been reported to recur or metastatise [2]. A recent paper [19] confirms the extremely good prognosis of this entity, so that the authors propose to rename this tumour as multilocular cystic renal cell neoplasm of low malignant potential, helping urologists to conservatively manage these patients.
papillary than in other RCCs and are especially frequent in the inherited forms of this subtype. Association with renal cortical adenomas is not uncommon. Small papillary RCCs have to be distinguished from renal cortical adenomas. According to the classification of RCC, any papillary tumour > 0.5 cm is defined as carcinoma [20]. Microscopically, papillary RCCs are characterised by tumour papillae containing a delicate fibrovascular core and a varying proportion of foamy macrophages. Psammomatous calcifications are common in the papillary cores as well as oedema and areas of hyalinised connective tissue. Two morphologic types of papillary RCC have been recognised. Type 1 tumours have papillae lined by small cells with pale, scanty cytoplasm and uniform nuclei with inconspicuous nucleoli. The cells are arranged in a single layer on the papillae. Type 2 tumours are composed of large cells with abundant eosinophilic cytoplasm and higher grade nuclei. The cells may form a single layer or show pseudostratification. It is thought that the distinction between the two types of papillary RCC may have prognostic implications, because type 1 tumours usually have lower grade and stage. Longer survival has been reported for type 1 as compared with type 2 papillary RCC [21]. Sarcomatoid dedifferentiation has been described in about 5% of papillary RCCs of both types and has been associated with poor prognosis [21]. 3.1.
Papillary RCCs react strongly with pancytokeratin and low-molecular-weight cytokeratins antibodies, AE1/AE3, Cam 5.2. Cytokeratin 7 reactivity has been reported for papillary RCC and is more frequent in type 1 than in type 2 tumours. RCC marker is expressed in >90% of cases, as is CD10. Interestingly, many tumours express parvalbumin and b-defensin-1. 3.2.
3.
Papillary RCC
Papillary RCCs, which account for about 10–15% of all RCCs, are malignant tumours composed of epithelial cells forming papillae or tubulopapillary structures. Macroscopically, papillary RCCs are wellcircumscribed tumours, reddish brown to golden yellow in colour, which often contain areas of hemorrhage, necrosis, and cystic degeneration. Multicentricity or bilaterality are more common in
Immunoprofile
Genetics
Genetic defects on chromosome 7 and 17 are the most common changes in papillary RCCs. In particular, both sporadic and familial papillary RCC are associated with mutations of the MET gene at chromosome 7, albeit with strikingly different frequencies [22]. The MET gene encodes for a receptor tyrosine kinase that is normally activated by hepatocyte growth factor, playing a key role in cell proliferation and immortalisation, motility, and invasion.
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4.
Chromophobe RCC
4.1.
The chromophobe subtype accounts for approximately 5% of all RCCs. It is a malignant renal tumour composed of large pale-to-eosinophilic cells with prominent cellular membranes. At macroscopy, this distinct type of RCC presents as a solitary and well-circumscribed tumour. In unfixed specimens, the cut surfaces are typically homogeneously brown or tan coloured, closely mimicking an oncocytoma. Microscopically, chromophobe RCCs have a solid growth pattern with focal psammomatous calcifications and fibrotic septa containing thick-walled blood vessels. Histologically, two major patterns have been recognised, referred to as the classic and eosinophilic types. In most cases a combination of the two occurs. The cells of the classic type usually have abundant pale vesicular cytoplasm with prominent cellular membranes due to the concentration of cell organelles at the periphery of the cytoplasm (so-called ‘‘plant-like’’ appearance). The eosinophilic variant of chromophobe carcinoma is composed of intensely eosinophilic cells with granular cytoplasm owing to an abundance of mitochondria. Microvesicles may concentrate around the nuclei, producing prominent clear perinuclear halos. The nuclei of both variants of chromophobe carcinoma are similar. They are irregular, often wrinkled (‘‘koilocytic-like’’), with small nucleoli. Sarcomatoid changes may occur. Both types of chromophobe carcinoma typically stain with the Hale colloidal iron tecnique, thus underlining the abundant content of mucopolysaccharides that distinguishes this type of RCC.
Immunoprofile
Chromophobe RCC reacts strongly with pancytokeratin and EMA antibodies. About 50% of tumours react for RCC marker and CD10, and most express RON, parvalbumin, and b-defensin-1. Chromophobe RCCs do not react for vimentin. Recently [23,24], Kit expression was reported in all cases of chromophobe RCC (and renal cell oncocytomas) but in no case of clear cell RCC. Thus, Kit reactivity can be seen as an additional diagnostic criterion for distinguishing chromophobe RCC from clear cell and papillary RCCs. 4.2.
Genetics
Most chromophobe RCCs are characterised by extensive chromosome loss [25]. Telomeric associations and telomere shortening have also been described [26].
5.
RCC grading and staging
5.1.
Grading
Fuhrman nuclear grade is used for all types of RCC. Both four-tiered and three-tiered grading systems are applied. The most common four-tiered nuclear grading system [27] is as follows: using a 10 objective, grade 1 cells have small hyperchromatic nuclei (resembling those of small mature lymphocytes) with indistinct nucleoli. Grade 2 cells have finely granular chromatin but incospicuous nucleoli. Grade 3 cells have ‘‘open’’ chromatin with
Table 3 – TNM staging T primary tumour TX primary tumour cannot be assessed T0 absence of primary tumour T1 7 cm tumour, limited to the kidney T1a 4 cm T1b > 4 cm but <7 cm T2 > 7 cm, limited to the kidney T3 extension into major veins or adrenal gland or perinephric tissues direct invasion but nor beyond Gerota fascia T3a adrenal gland or perinephric tissues* direct invasion but nor beyond Gerota fascia T3b gross extension into renal vein(s)y or vena cava or its wall below diaphragm T3c gross extension into vena cava or its wall above diaphragm T4 direct invasion beyond Gerota fascia
N regional lymph node metastasis
M distant metastasis
NX lymph nodes cannot be assessed N0 absence of lymph node metastasis N1 metastasis to 1 lymph node
MX distant metastasis cannot be assessed M0 absence of distant metastasis M1 distant metastasis
N2 metastasis to >1 lymph node
Renal sinus fat included* Segmental branches includedy
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prominent nucleoli. Nuclear grade 4 is characterised by nuclear pleomorphism and hypercromasia with single to multiple macronucleoli. Tumour grade is assigned according to the highest grade present. 5.2.
of renal tumours with clinical utility. Urologists should be aware that currently many molecular analyses can be performed on renal carcinomas, and when feasible, fresh samples sent to the pathologist.
Staging
References Staging is assigned based on the Union Internationale Contre le Cancer/American Joint Committee on Cancer (UICC/AJCC) 2002 classification of primary RCC (Table 3) [28,29]. This classification was recently reviewed [30,31] to validate its ability to predict patient outcome in comparison with the previous 1997 classification. The results of this study indicate that the 2002 primary tumour classification—where pT1 lesions are subdivided into pT1a and pT1b— provides excellent stratification of patients according to cancer-specific survival and has more predictive ability than the 1997 classification.
6.
Prognosis and future prospects
Prognosis of patients with RCCs is most accurately predicted by TNM stage. Within stages, Fuhrman grade has a strong predictive value. Although not considered in nuclear grading, sarcomatoid dedifferentiation is a strongly negative event [21]. Recently [4], histologic coagulative tumour necrosis was shown to be an independent prognostic factor of outcome for clear cell and chromophobe RCC, and its presence should be routinely reported and used in clinical assessement. In a series of papillary RCC, longer survivals were reported for type 1 when compared with type 2 tumours [21], suggesting that this distinction has prognostic significance. More recently [32], the prognostic value of the histologic subtype of RCC has been analysed in a large series of patients. The results suggest that the prognostic value of histologic subtype should not be considered comparable with TNM stage, Fuhrman grade, or performance status (the latter based on the Eastern Cooperative Oncology Group criteria [33]). As regards genetic markers, a recent cDNA microarray study indicated that gene expression profiling can divide RCCs into subgroups that predict survival after surgery independently of clinical prognostic factors [20]. Microarrays studies alongside cytogenetics have improved biologic understanding of the molecular subtypes of RCC in the ancient and new entities, offering a new promising approach for clinical diagnosis, prognosis, and possibly also therapeutic monitoring [34]. Studies are needed on large cohorts to further develop the molecular panels, allowing the precise molecular classification
[1] Kovacs G, Akhtar M, Beckwith BJ, et al. The Heidelberg classification of renal cell tumors. J Pathol 1997;183: 131–3. [2] Eble JN, Togashi K, Pisani P. Renal cell carcinoma. In: Eble JN, Sauter G, Epstein JI, Sesterhenn IA, editors. Pathology and genetics of tumors of the urinary system and male genital organs. World Health Organization Classification of Tumors. Lyon: IARC Press; 2004. p. 12–43. [3] Lopez-Beltran A, Scarpelli, Montironi R, et al. WHO classification of the renal tumors of the adults. Eur Urol 2006;49:798–805. [4] Sengupta S, Lohse CM, Leibovich BC, et al. Histologic coagulative necrosis as a prognostic indicator of renal cell carcinoma aggressiveness. Cancer 2005;104:511–20. [5] Kidney tumors in adults. Tumors of the kidney, bladder, and related urinary structures. In: Murphy WM, Grignon DJ, Perlman EJ, editors. Armed Forces Institute of Pathology Atlas of Tumor Pathology, Series 4. ARP Publisher; 2004. p. 120120. [6] Takahashi M, Kahnoski R, Gross D, Nicol D, Teh BT. Familial adult renal neoplasia. J Med Genet 2002;39:1–5. [7] Gronwald J, Storkel S, Holtgreve-Grez H, et al. Comparison of DNA gains and losses in primary renal cell carcinomas and metastatic sites: importance of 1q and 3p copy number changes in metastatic events. Cancer Res 1997;57:481–7. [8] Moch H, Presti Jr JC, Sauter G, et al. Genetic aberrations detected by comparative genomic hybridization are associated with clinical outcome in renal cell carcinoma. Cancer Res 1996;56:27–30. [9] Reiter RE, Anglard P, Liu S, Gnarra JR, Linehan WM. Chromosome 17p deletions and p53 mutations in renal cell carcinoma. Cancer Res 1993;53:3092–7. [10] Uchida T, Wada C, Shitara T, Egawa A, Mashimo S, Koshiba K. Infrequent involvement of p53 mutations and loss of heterozygosity of 17p in the tumorigenesis of renal cell carcinoma. J Urol 1993;150:1298–301. [11] Osipov V, Keating JT, Faul PN, Loda M, Datta MW. Expression of p27 and VHL in renal tumors. Appl Immunohistochem Mol Morphol 2002;10:344–50. [12] Schiavina R, Manferrari F, Bertaccini A, et al. Valore Prognostico della p27 nei Tumori Renali: Studio Clinico-Patologico. Abstracts XIII Congresso Nazionale Societa` Italiana di Urologia Oncologica. Arch Ital Urol Androl 2003;75:49 [in Italian]. [13] Shimazui T, Giroldi LA, Bringuier PP, Oosterwijk E, Schalken JA. Complex cadherin expression in renal cell carcinoma. Cancer Res 1996;56:3234–7. [14] Nicol D, Hii SI, Walsh M, et al. Vascular endothelial growth factor expression is increased in renal cell carcinoma. J Urol 1997;157:1482–6.
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[15] Slaton JW, Inoue K, Perrotte P, et al. Expression levels of genes that regulate metastasis and angiogenesis correlate with advanced pathological stage of renal cell carcinoma. Am J Pathol 2001;158:735–43. [16] Moch H, Sauter G, Gasser TC, et al. EGF-r gene copy number changes in renal cell carcinoma detected by fluorescence in situ hybridization. J Pathol 1998;184:424–9. [17] Schraml P, Kononen J, Bubendorf L, et al. Tissue microarrays for gene amplification surveys in many different tumor types. Clin Cancer Res 1999;5:1966–75. [18] Zhao H, Ljungberg B, Grankvist K, Rasmuson T, Tibshirani R, Brooks JD. Gene expression profiling predicts survival in conventional renal cell carcinoma. PLoS Biol 2006;3:1–10. [19] Suzigan S, Lopez-Beltran A, Montironi R, et al. Multilocular cystic renale cell carcinoma: a report of 45 cases of a kidney tumor of low malignant potential. Am J Clin Pathol 2006;125:217–22. [20] Storkel S, Eble JN, Adlakha K, et al. Classification of renal cell carcinoma: Workgroup No 1. Union Internationale Contre le Cancer (UICC) and the American Joint Committee on Cancer (AJCC). Cancer 1997;80:987–9. [21] Moch H, Gasser T, Amin MB, Torhorst J, Sauter G, Mihatsch MJ. Prognostic utility of the recently recommended histologic classification and revised TNM staging system of renal cell carcinoma: a Swiss experience with 588 tumors. Cancer 2000;89:604–14. [22] Cohen HT, McGovern FJ. Renal-cell carcinoma. N Engl J Med 2005;353:2477–90. [23] Wang HY, Millis SE. KIT and RCC are useful in distinguishing chromophobe renal cell carcinoma from the granular variant of clear cell renal cell carcinoma. Am J Surg Pathol 2005;29:640–6. [24] Huo L, Sugimura J, Tretiakova MS, et al. C-kit expression in renal oncocytomas and chromophobe renal cell carcinomas. Hum Pathol 2005;36:262–8.
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[25] Speicher MR, Schoell B, du Manoir S, et al. Specific loss of chromosomes 1, 2, 6, 10, 13, 17 and 21 in chromophobe renal cell carcinomas revealed by comparative genomic hybridization. Am J Pathol 1994;145:356–64. [26] Holzmann K, Blin N, Welter C, Zang KD, Seitz G, Henn W. Telomeric associations and loss of telomeric DNA repeats in renal tumors. Genes Chromosomes Cancer 1993;6:178–81. [27] Fuhrman SA, Lasky LC, Limas C. Prognostic significance of morphological parameters in renal cell carcinoma. Am J Surg Pathol 1982;6:655–63. [28] Greene LF, Page DL, Fleming D, et al. American Joint Committee on Cancer (AJCC) cancer staging manual. ed. 6 New York: Springer-Verlag; 2002. [29] Union Internationale Contre le Cancer. TNM classification of malignant tumors. ed. 6 New York: Wiley & Sons; 2002 . [30] Frank I, Blute ML, Leibovich BC, Cheville JC, Lohse CM, Zincke H. Independent validation of the 2002 American Joint Committee on Cancer primary tumor classification for renal cell carcinoma using a large, single institution cohort. J Urol 2005;173:1889–92. [31] Salama ME, Guru K, Stricker H, et al. pT1 substaging in renal cell carcinoma: validation of the 2002 TNM staging modification of malignant renal epithelial tumors. J Urol 2005;173:1492–5. [32] Patard JJ, Leray E, Rioux-Leclercq N, et al. Prognostic value of histologic subtypes in renal cell carcinoma: a multicenter experience. J Clin Oncol 2005;23:2763–71. [33] Elson PJ, Witte RS, Trump DL. Prognostic factors for survival in patients with recurrent or metastatic renal cell carcinoma. Cancer Res 1988;48:7310–3. [34] Yin-Goen Q, Dale J, Yang WL, et al. Advances in molecular classification of renal neoplasms. Histol Histopathol 2006;21:325–39.
available at www.sciencedirect.com journal homepage: www.europeanurology.com
Pathology and Molecular Pathogenesis of Renal Cell Carcinoma Barbara Corti a, Nicola Zucchini a, Benedetta Fabbrizio a, Giuseppe Martorana b, Riccardo Schiavina b, Antonia D’Errico Grigioni a, Walter Franco Grigioni a,* a
Pathology Division, F. Addarii Institute of Oncology, Department of Oncology and Haematology, S. Orsola–Malpighi Hospital, University of Bologna, Bologna, Italy b Department of Urology, University of Bologna, Bologna, Italy
Article info
Abstract
Keywords: Grade Molecular pathogenesis Pathology Prognosis Renal cell carcinoma Stage
Objectives: In this review, we summarise the World Health Organization (WHO) classification of renal cell carcinomas (RCCs) alongside grading and staging systems. General applications of immunohistochemistry, cytogenetics, and cDNA microarrays were reviewed with their implications in tumour diagnosis, prognosis, and therapy. Results: RCCs are classified according to the 2004 WHO classification, which defines three main histopathologic tumour subtypes with distinct clinical behaviour and underlying genetic defects: conventional (clear cell), papillary, and chromophobe RCC. Histopathologic classification and specific genetic mutations are crucial in distinguishing between familial and nonfamilial tumours. The most common four-tiered Fuhrman nuclear grade system is recommended for all types of RCC. Tumour grade is assigned according to the highest grade present; staging is assigned using the Union Internationale Contre le Cancer/American Joint Committee on Cancer 2002 classification. Conclusions: Prognosis of patients with RCCs is most accurately predicted by TNM stage. Within stages, Fuhrman grade has a strong predictive value. Although not considered in nuclear grading, sarcomatoid dedifferentiation is a severely negative event for all RCC subtypes. Histologic subtypes of RCCs are not independent prognostic factors comparable with TNM stage and Fuhrman grade. Histologic coagulative tumour necrosis was an independent prognostic factor of outcome for clear cell and chromophobe RCC. Immunohistochemical panels including RCC marker, CD10, and KIT are now available for differential diagnosis of the distinct RCC subtypes. Genetic studies have improved understanding of subtypes, offering a promising approach for clinical diagnosis, prognosis, and possibly therapy. Urologists should be aware that currently many molecular analyses can be performed on RCCs, and when feasible, fresh samples sent to the pathologist. # 2006 European Association of Urology. Published by Elsevier B.V. All rights reserved.
* Corresponding author. Istituto F. Addarii, Policlinico S. Orsola Malpighi, Viale ercolani 4/2, 40138, Bologna, Italy. Tel. +39 0516364546; Fax: +39 0516354403. E-mail address: [email protected] (W.F. Grigioni). 1569-9056/$ – see front matter # 2006 European Association of Urology. Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.eursup.2006.03.005
574
1.
european urology supplements 5 (2006) 573–579
Table 2 – Genetic defects in nonfamilial renal cell carcinoma
Introduction
Renal cell carcinomas (RCCs) arise from the renal epithelium and account for >90% of all renal malignancies occurring in adult men and women. About 2% of RCCs are associated with inherited syndromes; specific oncogenes or tumour suppressor genes and their mutations have been identified for most of these (Table 1). Distinct genetic defects have also been described in nonfamilial RCC (Table 2). The Heidelberg classification, which was introduced in 1997 [1], described the identified genetic defects of both sporadic and familial RCC in relation to histopathologic appearance. The 2004 World Health Organization (WHO) classification [2] distinguishes three main histologic subtypes: conventional (clear cell), papillary, and chromophobe RCC. Rarer subtypes include carcinoma of the collecting duct of Bellini and new diagnostic categories as medullary carcinoma, Xp11 carcinoma, carcinoma associated with neuroblastoma (in long-term survivors of childood neuroblastoma), and mucinous tubular and spindle cell carcinoma. In a recent paper [3], these rare new entities have been duly revised, confirming that recognition of these tumours may have important implications for the patient’s management. Additionally, ‘‘RCC, unclassified’’ was introduced as a novel diagnostic category to accommodate tumours that do not fit into any of the other morphologic categories. Representative examples of clear cell, papillary, and chromophobe RCC are shown in Fig. 1.
2.
Clear cell RCC
Histotype
Alterations
3 7 and 17 1, 2, 6, 10, 13, 17, 21
Deletions, mutations Trisomy and tetrasomy Chromosomal loss
CCRCC PRCC Chromophobe RCC
CCRCC = clear cell renal cell carcinoma; PRCC = papillary renal cell carcinoma.
tricity or bilaterality and early stage at the diagnosis are typical of inherited syndromes such as von Hippel-Lindau syndrome. Macroscopically, clear cell RCCs are round tumours that bulge out of the renal cortex. They are usually clearly demarcated from the adjacent renal parenchyma with a ‘‘pushing’’ border. All clear cell RCCs have a characteristic golden yellow appearance due to the rich lipid content of their cells. Cysts, hemorrhages, and calcifications are commonly encoutered. Tumour necrosis can also be present and should be routinely reported because it is a useful predictor of clinical outcome [4]. Microscopically, clear cell RCCs can present alveolar, acinar, or solid architectural patterns. A delicate vascular network of thin blood vessels is usually present. The cytoplasm of the neoplastic cells is usually clear, due to its lipid and glycogen content. A variable component of eosinophilic cells may be present. Nuclei are round to polygonal with indistinct nucleoli and finely distributed chromatin. Nuclear pleomorphism, prominent nucleoli, and coarse chromatin are typical features of high-grade tumours. 2.1.
Clear cell RCC, which is the most common histologic variant, is a malignant tumour composed of cells with clear or eosinophilic cytoplasm. It usually presents as a solitary cortical tumour, and it occurs with equal frequency in either kidney. Multicen-
Chromosomes
Immunoprofile
Clear cell RCCs commonly react with epithelial membrane antigen (EMA), low-molecular-weight cytokeratins (CK8, CK18, CK19), AE1, Cam 5.2, and vimentin. High-molecular-weight cytokeratins are rarely detected. MUC-1 and MUC-3 are consistently
Table 1 – Inherited renal cell carcinoma syndromes and related genetics defects Syndrome
Gene
Chromosome alterations
Pathologic appearence
von Hoppel-Lindau
VHL
3p25 loss of function mutations
Hereditary papillary renal carcinoma (HPRC) Hereditary leiomyomatosis and RCC Birt-Hogg-Dube`
MET
7q31 activating mutations
Multiple, bilateral CCRCC, phaeochromocytoma, CNS haemangioblastomas Multiple, bilateral PRCC, type 1
FH
1q42-43 inactivating mutations
BDH
17p11.2 inactivating mutations
Familial clear cell renal cancer (FCCRC)
3p translocations
Papillary renal cell carcinoma, non-type 1, cutaneous and uterine leiomyomas Multiple chromophobe and clear cell RCC and oncocytomas, skin tumours Multiple, bilateral CCRCC
CCRCC = clear cell renal cell carcinoma; CNS = central nervous system; PRCC = papillary renal cell carcinoma.
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Fig. 1 – Representative examples of clear cell (A), papillary (B), and chromophobe renal cell carcinoma (C). All tumours exhibit low-grade nuclei. Haematoxylin and eosin, 20.
expressed. b-Defensin-1 and parvalbumin are usually absent. Most clear cell RCCs react with RCC marker and CD10, which are useful for distinguishing the clear cell and chromophobe subtypes (see below). Of note, many clear cell RCCs react to placental alkaline phosphatase (PLAP) [5]. 2.2.
Genetics
Clear cell RCC can be a manifestation of von HippelLindau disease in association with mutiple extrarenal tumours, but it may also arise in other familial RCC syndromes (Table 1). All the inherited clear cell RCCs display VHL gene defects. The VHL gene is also involved in the majority of sporadic clear cell RCCs. In both istances, RCCs are characterised by late onset, unlike RCCs associated with Xp11.2 translocations, which predominantly affect children and young adults, although data on a few older patients have been reported [2]. Defects in the VHL gene arise
from allelic deletion, mutation, or epigenetic silencing in 60% of cases, making the VHL gene the major tumour suppressor gene in sporadic clear cell RCC. The inactivation of the VHL gene has effects on the VHL protein-regulated pathways. Normally, the VHL protein negatively regulates the transcriptional activators hypoxia-inducible factor (HIF) 1a and 2a, which activates genes involved in cell proliferation, angiogenesis, and extracellular matrix formation. Additional tumour suppressor genes associated with inherited and sporadic clear cell RCCs are also found on chromosome 3 [6]. Clonal accumulation of genetic abnormalites on many other chromosomoses then supervenes during clear cell RCC progression and metastasis [7,8]. Expression levels of a wide variety of genes have been investigated, including p53 and p27. The role of p53 overexpression in clear cell RCC is still debated; only a few studies recorded an association with poor prognosis [9,10]. Expression of p27 has been recently investi-
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gated in RCCs [11,12]. In clear cell RCCs, significant associations have been noted between decreased p27 levels and increasing tumour size and Fuhrman grade. However, no correlation has been found between decreased p27 levels and survival. Many studies suggest that high levels of vascular endothelial growth factor (VEGF) and E-cadherin may play a role in rapidity of tumour cell proliferation and progression [13–15]. Clear cell RCCs rarely exhibit high levels of gene amplifications. In particular, amplification of the EGFR gene is very uncommon and HER2/neu amplifications are rare or absent [16,17]. cDNA microarrays seem to provide new prognostic algorithms for clear cell RCCs, as recently reported [18]. 2.3.
Multilocular cystic RCC
About 5% of clear cell RCCs are predominantly cystic. These so-called cystic or multilocular cystic RCCs are thought to be subtypes of clear cell RCCs. The tumours are composed of noncomunicating cysts separated by thick fibrotic septa that resemble a multilocular cyst. The correct diagnosis is made on detection of small groups of low-grade clear cells in the walls of the cysts. Usually, the epithelium lining the cysts is attenuated or absent. The septa may be calcified (only rarely with ossification). Multilocular cystic RCCs have to be distinguished from clear cell RCCs exhibiting cystic changes; the latter commonly display expansile solid nodules of clear cells in their cystic walls or papillary projections lined by clear cells. Recognition of multilocular cystic RCC is extremely important because of its favourable clinical behaviour. In fact, no tumour with features of multilocular cystic RCC has ever been reported to recur or metastatise [2]. A recent paper [19] confirms the extremely good prognosis of this entity, so that the authors propose to rename this tumour as multilocular cystic renal cell neoplasm of low malignant potential, helping urologists to conservatively manage these patients.
papillary than in other RCCs and are especially frequent in the inherited forms of this subtype. Association with renal cortical adenomas is not uncommon. Small papillary RCCs have to be distinguished from renal cortical adenomas. According to the classification of RCC, any papillary tumour > 0.5 cm is defined as carcinoma [20]. Microscopically, papillary RCCs are characterised by tumour papillae containing a delicate fibrovascular core and a varying proportion of foamy macrophages. Psammomatous calcifications are common in the papillary cores as well as oedema and areas of hyalinised connective tissue. Two morphologic types of papillary RCC have been recognised. Type 1 tumours have papillae lined by small cells with pale, scanty cytoplasm and uniform nuclei with inconspicuous nucleoli. The cells are arranged in a single layer on the papillae. Type 2 tumours are composed of large cells with abundant eosinophilic cytoplasm and higher grade nuclei. The cells may form a single layer or show pseudostratification. It is thought that the distinction between the two types of papillary RCC may have prognostic implications, because type 1 tumours usually have lower grade and stage. Longer survival has been reported for type 1 as compared with type 2 papillary RCC [21]. Sarcomatoid dedifferentiation has been described in about 5% of papillary RCCs of both types and has been associated with poor prognosis [21]. 3.1.
Papillary RCCs react strongly with pancytokeratin and low-molecular-weight cytokeratins antibodies, AE1/AE3, Cam 5.2. Cytokeratin 7 reactivity has been reported for papillary RCC and is more frequent in type 1 than in type 2 tumours. RCC marker is expressed in >90% of cases, as is CD10. Interestingly, many tumours express parvalbumin and b-defensin-1. 3.2.
3.
Papillary RCC
Papillary RCCs, which account for about 10–15% of all RCCs, are malignant tumours composed of epithelial cells forming papillae or tubulopapillary structures. Macroscopically, papillary RCCs are wellcircumscribed tumours, reddish brown to golden yellow in colour, which often contain areas of hemorrhage, necrosis, and cystic degeneration. Multicentricity or bilaterality are more common in
Immunoprofile
Genetics
Genetic defects on chromosome 7 and 17 are the most common changes in papillary RCCs. In particular, both sporadic and familial papillary RCC are associated with mutations of the MET gene at chromosome 7, albeit with strikingly different frequencies [22]. The MET gene encodes for a receptor tyrosine kinase that is normally activated by hepatocyte growth factor, playing a key role in cell proliferation and immortalisation, motility, and invasion.
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4.
Chromophobe RCC
4.1.
The chromophobe subtype accounts for approximately 5% of all RCCs. It is a malignant renal tumour composed of large pale-to-eosinophilic cells with prominent cellular membranes. At macroscopy, this distinct type of RCC presents as a solitary and well-circumscribed tumour. In unfixed specimens, the cut surfaces are typically homogeneously brown or tan coloured, closely mimicking an oncocytoma. Microscopically, chromophobe RCCs have a solid growth pattern with focal psammomatous calcifications and fibrotic septa containing thick-walled blood vessels. Histologically, two major patterns have been recognised, referred to as the classic and eosinophilic types. In most cases a combination of the two occurs. The cells of the classic type usually have abundant pale vesicular cytoplasm with prominent cellular membranes due to the concentration of cell organelles at the periphery of the cytoplasm (so-called ‘‘plant-like’’ appearance). The eosinophilic variant of chromophobe carcinoma is composed of intensely eosinophilic cells with granular cytoplasm owing to an abundance of mitochondria. Microvesicles may concentrate around the nuclei, producing prominent clear perinuclear halos. The nuclei of both variants of chromophobe carcinoma are similar. They are irregular, often wrinkled (‘‘koilocytic-like’’), with small nucleoli. Sarcomatoid changes may occur. Both types of chromophobe carcinoma typically stain with the Hale colloidal iron tecnique, thus underlining the abundant content of mucopolysaccharides that distinguishes this type of RCC.
Immunoprofile
Chromophobe RCC reacts strongly with pancytokeratin and EMA antibodies. About 50% of tumours react for RCC marker and CD10, and most express RON, parvalbumin, and b-defensin-1. Chromophobe RCCs do not react for vimentin. Recently [23,24], Kit expression was reported in all cases of chromophobe RCC (and renal cell oncocytomas) but in no case of clear cell RCC. Thus, Kit reactivity can be seen as an additional diagnostic criterion for distinguishing chromophobe RCC from clear cell and papillary RCCs. 4.2.
Genetics
Most chromophobe RCCs are characterised by extensive chromosome loss [25]. Telomeric associations and telomere shortening have also been described [26].
5.
RCC grading and staging
5.1.
Grading
Fuhrman nuclear grade is used for all types of RCC. Both four-tiered and three-tiered grading systems are applied. The most common four-tiered nuclear grading system [27] is as follows: using a 10 objective, grade 1 cells have small hyperchromatic nuclei (resembling those of small mature lymphocytes) with indistinct nucleoli. Grade 2 cells have finely granular chromatin but incospicuous nucleoli. Grade 3 cells have ‘‘open’’ chromatin with
Table 3 – TNM staging T primary tumour TX primary tumour cannot be assessed T0 absence of primary tumour T1 7 cm tumour, limited to the kidney T1a 4 cm T1b > 4 cm but <7 cm T2 > 7 cm, limited to the kidney T3 extension into major veins or adrenal gland or perinephric tissues direct invasion but nor beyond Gerota fascia T3a adrenal gland or perinephric tissues* direct invasion but nor beyond Gerota fascia T3b gross extension into renal vein(s)y or vena cava or its wall below diaphragm T3c gross extension into vena cava or its wall above diaphragm T4 direct invasion beyond Gerota fascia
N regional lymph node metastasis
M distant metastasis
NX lymph nodes cannot be assessed N0 absence of lymph node metastasis N1 metastasis to 1 lymph node
MX distant metastasis cannot be assessed M0 absence of distant metastasis M1 distant metastasis
N2 metastasis to >1 lymph node
Renal sinus fat included* Segmental branches includedy
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prominent nucleoli. Nuclear grade 4 is characterised by nuclear pleomorphism and hypercromasia with single to multiple macronucleoli. Tumour grade is assigned according to the highest grade present. 5.2.
of renal tumours with clinical utility. Urologists should be aware that currently many molecular analyses can be performed on renal carcinomas, and when feasible, fresh samples sent to the pathologist.
Staging
References Staging is assigned based on the Union Internationale Contre le Cancer/American Joint Committee on Cancer (UICC/AJCC) 2002 classification of primary RCC (Table 3) [28,29]. This classification was recently reviewed [30,31] to validate its ability to predict patient outcome in comparison with the previous 1997 classification. The results of this study indicate that the 2002 primary tumour classification—where pT1 lesions are subdivided into pT1a and pT1b— provides excellent stratification of patients according to cancer-specific survival and has more predictive ability than the 1997 classification.
6.
Prognosis and future prospects
Prognosis of patients with RCCs is most accurately predicted by TNM stage. Within stages, Fuhrman grade has a strong predictive value. Although not considered in nuclear grading, sarcomatoid dedifferentiation is a strongly negative event [21]. Recently [4], histologic coagulative tumour necrosis was shown to be an independent prognostic factor of outcome for clear cell and chromophobe RCC, and its presence should be routinely reported and used in clinical assessement. In a series of papillary RCC, longer survivals were reported for type 1 when compared with type 2 tumours [21], suggesting that this distinction has prognostic significance. More recently [32], the prognostic value of the histologic subtype of RCC has been analysed in a large series of patients. The results suggest that the prognostic value of histologic subtype should not be considered comparable with TNM stage, Fuhrman grade, or performance status (the latter based on the Eastern Cooperative Oncology Group criteria [33]). As regards genetic markers, a recent cDNA microarray study indicated that gene expression profiling can divide RCCs into subgroups that predict survival after surgery independently of clinical prognostic factors [20]. Microarrays studies alongside cytogenetics have improved biologic understanding of the molecular subtypes of RCC in the ancient and new entities, offering a new promising approach for clinical diagnosis, prognosis, and possibly also therapeutic monitoring [34]. Studies are needed on large cohorts to further develop the molecular panels, allowing the precise molecular classification
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