Atypical epithelial proliferations in acquired renal cystic disease harbor cytogenetic aberrations

Acquired cystic disease associated renal cell carcinoma: A clinicopathologic and molecular study of 31 tumors

Acquired cystic disease associated renal cell carcinomas (ACD-RCC) are rare and their molecular and histopathological characteristics are still being explored. We therefore investigated the clinicopathologic and molecular characteristics of 31 tumors. The patients were predominantly male (n = 30), with tumors mainly left-sided (n = 17), unifocal (n = 19), and unilateral (n = 29) and a mean tumor size of 25 mm (range, 3-65 mm). Microscopically, several histologic patterns were present, including pure classic sieve-like (n = 4), and varied proportions of mixed classic sieve-like with papillary (n = 23), tubulocystic (n = 9), compact tubular (n = 4) and solid (n = 1) patterns. Calcium-oxalate crystals were seen in all tumors. Molecular analysis of 9 tumors using next generation sequencing showed alterations in SMARCB1 in 3 tumors (1 with frameshift deletion and 2 with copy number loss in chromosome 22 involving SMARCB1 region), however, INI1 stain was retained in all. Nonrecurrent genetic alterations in SETD2, NF1, NOTCH4, BRCA2 and CANT1 genes were also seen. Additionally, MTOR p.Pro351Ser was identified in one tumor. Copy number analysis showed gains in chromosome 16 (n = 5), 17 (n = 2) and 8 (n = 2) as well as loss in chromosome 22 (n = 2). In summary, ACD-RCC is a recognized subtype of kidney tumors, with several histological architectural patterns. Our molecular data identifies genetic alterations in chromatin modifying genes (SMARCB1 and SETD2), which may suggest a role of such genes in ACD-RCC development.

Tumors masquerading as type 2 papillary renal cell carcinoma: pathologists' ever-expanding differential diagnosis for a heterogeneous group of entities

Although papillary renal cell carcinoma has historically been classified as either type 1 or type 2, data from The Cancer Genome Atlas (TCGA) has demonstrated significant genomic heterogeneity in tumors classified as "type 2 papillary renal cell carcinoma" (T2PRCC). Papillary renal cell carcinoma is expected to have a favorable clinical course compared to clear cell renal cell carcinoma (CCRCC). However, tumors with poor outcome more similar to CCRCC were included in the T2PRCC cohort studied by the TCGA. The differential diagnosis for T2PRCC includes a variety of other renal tumors, including aggressive entities such as TFE3 translocation-associated renal cell carcinoma, TFEB-amplified renal cell carcinoma, fumarate hydratase-deficient renal cell carcinoma, high-grade CCRCC, and collecting duct carcinoma. Accurate classification of these tumors is important for prognostication and selection of therapy.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

Renal Cell Tumors: Molecular Findings Reshaping Clinico-pathological Practice

Over the past 20 years, the number of subtypes of renal epithelial cell neoplasia has grown. This growth has resulted from detailed histological and immunohistochemical characterization of these tumors and their correlation with clinical outcomes. Distinctive molecular phenotypes have validated the unique nature of many of these tumors. This growth of unique renal neoplasms has continued after the 2016 World Health Organization (WHO) Classification of Tumours. A consequence is that both the pathologists who diagnose the tumors and the clinicians who care for these patients are confronted with a bewildering array of renal cell carcinoma variants. Many of these variants have important clinical features, i.e. familial or syndromic associations, genomics alterations that can be targeted with systemic therapy, and benignancy of tumors previously classified as carcinomas. Our goal in the review is to provide a practical guide to help recognize these variants, based on small and distinct sets of histological features and limited numbers of immunohistochemical stains, supplemented, as necessary, with molecular features.

Contemporary Renal Tumor Categorization With Biomarker and Translational Updates: A Practical Review

CONTEXT.—

Renal tumor classification has evolved in recent decades, as evidenced by the comparable complexity of the 2016 revision to the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. A recent expansion of the knowledge base surrounding the cells of origin and evolutionary genomic characteristics of renal tumors has led to molecular characterization of novel entities and enriched understanding of established entities. This pace of research and its implementation into clinical practice has again begun to surpass that of our own classification schemata, with significant discoveries having been made since the introduction of the 2016 revision to the World Health Organization classification. In particular, biomarkers for renal tumor diagnosis and prognosis are in translation for future clinical application.

OBJECTIVES.—

To provide a brief framework for clinical characterization of renal tumors rooted in morphologic assessment, to briefly review the current and future status of renal tumor biomarkers with an emphasis on practical use of these ancillary tools for accurate diagnosis, and to discuss the impact of emerging technologies and clinical trials relevant to renal cell carcinoma classification and biomarker development.

DATA SOURCES.—

We review recent literature relevant to renal tumor classification (including established and proposed entities), focusing on molecular characterization and biomarker assessment.

CONCLUSIONS.—

Accurate renal tumor diagnosis requires an up-to-date understanding of renal tumor classification, including an awareness of morphologic clues that should stimulate consideration of molecularly defined entities, as well as the ancillary biomarker testing required to confirm diagnoses.

Acquired Cystic Disease-associated Renal Cell Carcinoma (ACKD-RCC)-like Cysts

Acquired cystic disease-associated renal cell carcinoma (ACKD-RCC), originally described by Tickoo and colleagues, is found exclusively in patients with end-stage renal disease. Tickoo and colleagues noted: "Many of the tumors (16 of 24 dominant tumors) appeared to arise in a cyst, most often completely filling the cystic space. The cells lining such cysts were morphologically similar to those in the rest of the tumor." Subsequent literature lacks analysis of cysts lined by cells identical to ACKD-RCC, yet lacking areas of solid growth. The current study evaluates 16 cases ACKD-RCC-like cysts. All specimens were nephrectomies and occurred in the setting of end-stage renal disease. Of the 16 cases, 9 were in men. Patient's ages ranged from 32 to 66 years (median: 57). The cysts ranged in size from 0.2 to 2.5 cm. Twelve cases had unilateral cysts with the remaining 4 seen in both kidneys. Nine cysts were multilocular, 6 unilocular, and 1 consisted of closely clustered cysts. The atypical cysts showed architectural variation. One cyst was lined by a single layer of atypical cells (1/16), whereas in the majority these were either focally lined by 2 to 4 cell layers of atypical cells (6/16 cases) or showed occasional short papillary formations (9/16). Calcium oxalate crystals were noted in cyst walls in 7/16 cases. A total of 12/16 cases had separate RCCs (2 cases with 2 RCCs each; 1 case with 3). Carcinoma ranged in size from 3 mm to 5 cm in the largest dimension: 4 were pT1 ACKD-RCC; 5 were pT1 papillary RCC; 5 were pT1 clear cell papillary RCC; 1 was pT3 clear cell RCC; and 1 pT1 unclassified. Our study formally analyzes for the first time in the literature atypical cysts lined with vacuolated cells with eosinophilic cytoplasm that are likely the earliest precursors of ACKD-RCC. When these cysts are encountered, especially ones that are multilocular or clustered, they may be misdiagnosed as ACKD-RCC. ACKD-RCC-like cysts should be recognized as a distinct entity from ACKD-RCC, defined by the lack of any solid nodular growth within the cyst.

Acquired Cystic Disease-associated Renal Cell Carcinoma (ACD-RCC): A Multiinstitutional Study of 40 Cases With Clinical Follow-up

The incidence of renal cell carcinoma (RCC) is known to be higher in patients with end-stage renal disease, including those with acquired cystic kidney disease due to dialysis. Acquired cystic disease (ACD)-associated RCC was recently incorporated into the 2016 WHO Classification of Tumors of the Urinary System and Male Genital Tract as a distinct entity and is reportedly the most common RCC arising in end-stage renal disease. In this study, we sought to further describe clinicopathologic findings in a large series of ACD-RCC, emphasizing histologic features, immunophenotype, clinical outcome, and patterns of disease spread. We collected 40 previously unpublished cases of ACD-RCC with mean clinical follow-up of 27 months (median, 19 mo; range, 1 to 126 mo). Mean tumor size was 2.7 cm (median, 2.4 cm), and 32 tumors (80%) were confined to the kidney (pT stage less than pT3a). International Society of Urological Pathology grade was 3 in 37 cases (92.5%), grade 2 in 1 case (2.5%), and grade 4 in 2 cases (5%). Architectural variability among ACD-RCC was common, as 39 cases (98%) showed varying combinations of tubular, cystic, solid, and/or papillary growth. ACD-RCC frequently occurred in association with other renal tumor subtypes within the same kidney, including papillary RCC (14 patients), papillary adenomas (7 cases), clear cell papillary RCC (5 cases), clear cell RCC (1 case), and RCC, unclassified type (1 case). A previously undescribed pattern of perinephric and renal sinus adipose tissue involvement by dilated epithelial cysts with minimal or absent intervening capsule or renal parenchyma was identified in 20 cases (50%); these cysts were part of the tumor itself in 5 cases (25%) and were part of the non-neoplastic acquired cystic change in the background kidney in the remaining 15 cases (75%). Of the 24 cases (60%) with tissue available for immunohistochemical stains, 19 (79%) were positive for PAX8, 20 (83%) showed negative to patchy expression of cytokeratin 7, and 24 (100%) were both positive for AMACR and negative for CD117. Fumarate hydratase expression was retained in all tumors, including those with nuclear features resembling fumarate hydratase-deficient RCCs. Of the 36 patients (90%) with available follow-up information, 4 (11%) experienced adverse events: 2 patients developed a local recurrence, 1 patient experienced multiple visceral metastases and subsequently died of disease, and 1 patient developed metastases to regional lymph nodes only. One local recurrence and the lymph node only metastasis both had an unusual, exclusively cystic pattern of growth. In summary, we present the largest clinicopathologic series of ACD-RCC to date and describe previously unreported cystic patterns of local soft tissue involvement and recurrence/metastases.

Precursor Lesions of Urologic Malignancies

CONTEXT

- Precursor lesions of urologic malignancies are established histopathologic entities, which are important not only to recognize for clinical purposes, but also to further investigate at the molecular level in order to gain a better understanding of the pathogenesis of these malignancies.

OBJECTIVE

- To provide a brief overview of precursor lesions to the most common malignancies that develop within the genitourinary tract with a focus on their clinical implications, histologic features, and molecular characteristics.

DATA SOURCES

- Literature review from PubMed, urologic pathology textbooks, and the 4th edition of the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. All photomicrographs were taken from cases seen at Weill Cornell Medicine or from the authors' personal slide collections.

CONCLUSIONS

- The clinical importance and histologic criteria are well established for the known precursor lesions of the most common malignancies throughout the genitourinary tract, but further investigation is warranted at the molecular level to better understand the pathogenesis of these lesions. Such investigation may lead to better risk stratification of patients and potentially novel treatments.

Acquired Cystic Disease-Associated Renal Cell Carcinoma: Review of Pathogenesis, Morphology, Ancillary Tests, and Clinical Features

Acquired cystic disease-associated renal cell carcinoma (ACD-RCC) is a recently described subtype of RCC found in individuals with ACD of the kidney. Because of underrecognition, information regarding this lesion is sparse but continues to accumulate with each new report. Herein, a thorough literature review amassing the current understanding of this unique neoplasm is presented. Discussion focuses on clinical features, pathogenesis, disease outcome, and relation to the duration of dialysis. The macroscopic and characteristic microscopic features are described with illustrations. Compared with previous opinion, compiled immunohistochemical data may now allow for recognition of a unique immunophenotypic pattern of ACD-RCC. Distinction of ACD-RCC from clear cell and papillary RCCs based on molecular genetic information is deliberated, including a summary of the most frequently detected cytogenetic abnormalities. The key morphologic and immunophenotypic patterns used to distinguish this entity from a comprehensive differential diagnosis are provided.

Atypical Renal Cysts: A Morphologic, Immunohistochemical, and Molecular Study

There is a lack of standardized nomenclature for renal cysts lined by multiple cell layers or with short papillary projections but without nests of epithelial cells within the stroma. We retrieved 29 cases (15 nephrectomies, 14 partial nephrectomies) from the surgical pathology files of Johns Hopkins Hospital from 1993 to 2014 and performed immunohistochemistry for CK7, alpha-methylacyl-CoA racemase (AMACR), CAIX, and CD10 and fluorescence in situ hybridization for trisomy 7 and 17 and 3p deletion. The mean age at excision was 58 years (range, 29 to 80 y) with 16 men and 13 women. Mean size was 2.9 cm (range, 0.3 to 10 cm). The cysts were grouped by their morphology into (1) clear cell, (2) eosinophilic stratified, and (3) eosinophilic papillary. By immunohistochemistry, 7/9 (78%) of the clear cell cases were diffusely positive for both CK7 and CAIX resembling the pattern seen in clear cell papillary renal cell carcinoma. The majority of eosinophilic stratified (4/6; 67%) and eosinophilic papillary (12/14; 86%) cases were positive for CK7 and had variable staining for AMACR, CD10, or CAIX, suggesting a differentiation more aligned with papillary renal cell carcinoma. The most common molecular alterations detected were trisomy 17 (n=6) and trisomy 7 (n=4). One case showed deletion of chromosome 3p. Clinical follow-up information was available in 23 patients; 20 were alive with no evidence of disease after a median follow-up of 20 months (range, 3 to 120 mo), 1 patient was dead due to metastatic lung cancer, 1 of sepsis, and 1 of unknown reason. Atypical renal cysts present as complex radiologic lesions, as secondary lesions in patients with a renal mass, or in a background of chronic renal disease. These atypical cysts appear heterogenous, and some follow in their morphology and immunoprofile with well-established renal tumors. The presence of 3p deletion and trisomy 7/17 suggests that in some cases they may be precursors of renal cell carcinoma. Longer follow-up with more cases is needed, but on the basis of our data, these lesions should not be diagnosed as carcinoma.

Clinical and pathological outcomes of renal cell carcinoma (RCC) in native kidneys of patients with end-stage renal disease: a long-term comparative retrospective study with RCC diagnosed in the general population

PURPOSE

Patients with end-stage renal disease (ESRD) have an increased risk of developing renal cell carcinoma (RCC). This retrospective study compared clinical and pathological outcomes of RCC occurring in native kidneys of patients with ESRD (whether they underwent kidney transplantation or not) with those of renal tumors diagnosed in the general population.

METHODS

The study included a total of 533 patients with RCC. The ESRD cohort included 92 patients with RCC in native kidneys. Of these, 58 and 34 cases were identified before (pre-Tx group) and after kidney transplantation (post-Tx group), respectively. The control group was composed of 441 RCCs diagnosed in the general population. Variables were compared by chi-square and Student's t tests. Cancer-specific survival was assessed by Kaplan-Meier and Cox methods.

RESULTS

The ESRD groups had smaller (P = 0.001), lower-grade, and lower-stage tumors than the non-ESRD group (P = 0.001). The papillary RCC rate was higher in the ESRD groups (P = 0.01). Ten-year cancer-specific survivals were 94.5, 87.9, and 74.6 % in pre-Tx, post-Tx, and non-ESRD patients, respectively (P = 0.003). Mean follow-up was 90.2 months. At multivariate analysis, tumor size (HR = 1.10), pathological stage (HR = 1.46), presence of nodal (HR = 2.22) and visceral metastases (HR = 3.49), and Fuhrman grade (HR = 1.48) were independent adverse prognostic factors for cancer-specific survival.

CONCLUSIONS

Native kidney RCCs arising in ESRD patients are lower stage and lower grade as compared to RCCs diagnosed in the general population, and these tumors exhibit favorable clinical and outcome features.

Clinical characteristics and outcomes in renal transplant recipients with renal cell carcinoma in the native kidney

BACKGROUND/AIMS

We investigated the incidence and clinical characteristics of renal cell carcinoma (RCC) in the native kidney of renal transplant recipients.

METHODS

Between 1991 and 2010, 1,425 patients underwent kidney transplantation at our institution. We retrospectively evaluated the clinical features and outcomes in renal transplant patients with RCC in the native kidney after renal transplantation.

RESULTS

The patients included three males and two females with a mean age of 63 years (range, 52 to 74). The incidence of RCC was 0.35%. The median interval between renal transplantation and RCC occurrence was 16.2 years (range, 9 to 20). All of our patients with RCC had developed renal cysts either before (n = 3) or after (n = 2) renal transplantation. The mean duration of dialysis was 12 months (range, 2 to 39). Of the five patients, four underwent dialysis treatment for less than 8 months. All the RCCs were low grade at the time of diagnosis. Four patients underwent radical nephrectomy, and one patient refused the operation. The four patients who underwent radical nephrectomy showed no evidence of local recurrence or distant metastasis during the median follow-up of 2.9 years. However, the patient who did not undergo surgery developed spinal metastasis from the RCC 6 years later.

CONCLUSIONS

This study suggests that the follow-up period is an important factor for the development of RCC in renal transplant recipients, and more vigorous screening with a longer follow-up period is required in renal transplant recipients.

Genomic profiling of renal cell carcinoma in patients with end-stage renal disease

The purpose of the present study was to determine the genomic profile of renal cell carcinoma (RCC) in end-stage renal disease (ESRD) by analyzing genomic copy number aberrations. Seventy-nine tumor samples from 63 patients with RCC-ESRD were analyzed by array comparative genomic hybridization using the Agilent Whole Human Genome 4 × 44K Oligo Micro Array (Agilent Technologies Inc., Palo Alto, CA, USA). Unsupervised hierarchical clustering analysis revealed that the 63 cases could be divided into two groups, Clusters A and B. Cluster A was comprised mainly of clear cell RCC (CCRCC), whereas Cluster B was comprised mainly of papillary RCC (PRCC), acquired cystic disease (ACD)-associated RCC, and clear cell papillary RCC. Analysis of the averaged frequencies revealed that the genomic profiles of Clusters A and B resembled those of sporadic CCRCC and sporadic PRCC, respectively. Although it has been proposed on the basis of histopathology that ACD-associated RCC, clear cell papillary RCC and PRCC-ESRD are distinct subtypes, the present data reveal that the genomic profiles of these types, categorized as Cluster B, resemble one another. Furthermore, the genomic profiles of PRCC, ACD-associated RCC and clear cell papillary RCC admixed in one tissue tended to resemble one another. On the basis of genomic profiling of RCC-ESRD, we conclude that the molecular pathogenesis of CCRCC-ESRD resembles that of sporadic CCRCC. Although various histologic subtypes of non-clear cell RCC-ESRD have been proposed, their genomic profiles resemble those of sporadic PRCC, suggesting that the molecular pathogenesis of non-CCRCC-ESRD may be related to that of sporadic PRCC.

Renal cell carcinoma (RCC) in patients with end-stage renal disease exhibits many favourable clinical, pathologic, and outcome features compared with RCC in the general population

BACKGROUND

Patients with end-stage renal disease (ESRD) are at risk of developing renal tumours.

OBJECTIVE

Compare clinical, pathologic, and outcome features of renal cell carcinomas (RCCs) in ESRD patients and in patients from the general population.

DESIGN, SETTING, AND PARTICIPANTS

Twenty-four French university departments of urology participated in this retrospective study.

INTERVENTION

All patients were treated according to current European Association of Urology guidelines.

MEASUREMENTS

Age, sex, symptoms, tumour staging and grading, histologic subtype, and outcome were recorded in a unique database. Categoric and continuous variables were compared by using chi-square and student statistical analyses. Cancer-specific survival (CSS) was assessed by Kaplan-Meier and Cox methods.

RESULTS AND LIMITATIONS

The study included 1250 RCC patients: 303 with ESRD and 947 from the general population. In the ESRD patients, age at diagnosis was younger (55 ± 12 yr vs 62 ± 12 yr); mean tumour size was smaller (3.7 ± 2.6 cm vs 7.3 ± 3.8 cm); asymptomatic (87% vs 44%), low-grade (68% vs 42%), and papillary tumours were more frequent (37% vs 7%); and poor performance status (PS; 24% vs 37%) and advanced T categories (≥ 3) were more rare (10% vs 42%). Consistently, nodal invasion (3% vs 12%) and distant metastases (2% vs 15%) occurred less frequently in ESRD patients. After a median follow-up of 33 mo (range: 1-299 mo), 13 ESRD patients (4.3%), and 261 general population patients (27.6%) had died from cancer. In univariate analysis, histologic subtype, symptoms at diagnosis, poor PS, advanced TNM stage, high Fuhrman grade, large tumour size, and non-ESRD diagnosis context were adverse predictors for survival. However, only PS, TNM stage, and Fuhrman grade remained independent CSS predictors in multivariate analysis. The limitation of this study is related to the retrospective design.

CONCLUSIONS

RCC arising in native kidneys of ESRD patients seems to exhibit many favourable clinical, pathologic, and outcome features compared with those diagnosed in patients from the general population.

Native renal cysts and dialysis duration are risk factors for renal cell carcinoma in renal transplant recipients

Urinary tract cancers are the third most common cancers in renal transplant recipients (RTX). This study examined the impact of dialysis duration and native renal cyst(s) (NRC) on renal cell carcinoma (RCC) occurrence among 1036 RTX followed-up from 1995 to July 2007. Abdominal ultrasonography was planned within 1-month of transplant, then every 5 years, or 2 years if renal cysts developed. Based on presence and time of development of NRC, RTX were grouped into those with no (No-NRC), new (New-NRC), preexisting (Pre-NRC) and time-indeterminate NRC (TI-NRC). Ten asymptomatic RTX were diagnosed with RCC at a median of 5.8 years posttransplant and had 5-year graft and patient survivals of 90% and 100%, respectively, following appropriate therapy. RCC occurred only in Pre-NRC and TI-NRC who had significantly longer dialysis duration than No- or New-NRC (6.7 ± 3.9 and 3.3 ± 3.2 vs. 2.7 ± 3.1 and 2.6 ± 2.4 years, respectively). These results suggest that NRC and increased dialysis duration are risk factors for RCC posttransplant. Since early treatment of RCC gives excellent outcomes, regular ultrasonography performed within a month of transplantation, then every 5 years for those without cysts and every 2 years for those with cysts for early detection of RCC is recommended.

The non-neoplastic kidney in tumor nephrectomy specimens: what can it show and what is important?

Surgical nephrectomy is a procedure that has been performed for nearly 100 years. In the presence of a normal contralateral kidney, such as in a renal transplant donor or child with Wilms tumor, it is a benign procedure without deleterious consequences on the remaining kidney. However, many adults and some children postnephrectomy will develop chronic kidney disease. The non-neoplastic kidney in tumor resections may harbor a large number of developmental and acquired diseases predictive of this outcome or that convey other medically significant information. Examination of the non-neoplastic kidney is a fertile opportunity to identify these unsuspected conditions that may ultimately dictate the subsequent clinical course and influence the medical care provided. This review discusses the consequences of unilateral and partial nephrectomy, and illustrates many conditions that may be encountered in the non-neoplastic cortex with a discussion of their clinical implications.

Immunohistochemical and molecular genetic profiling of acquired cystic disease-associated renal cell carcinoma

AIMS

Acquired cystic disease-associated renal cell carcinoma (ACD-associated RCC) is a unique neoplasm that specifically develops in the background of acquired cystic disease of the kidney. The aim was to analyse nine ACD-associated RCCs from three patients to determine their immunohistochemical and molecular characteristics using immunohistochemistry, comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH).

METHODS AND RESULTS

ACD-associated RCC preferentially expressed proximal nephron phenotype (CD10+ /RCC marker+/alpha-methylacyl-CoA racemase+ /glutathione S-transferase-alpha+ /BerEP4+ /cytokeratin 7- /E-cadherin- /high-molecular-weight cytokeratin- /MOC31-). CGH combined with FISH demonstrated non-random chromosomal gains clustering on chromosomes 3 (8/9), 7 (6/9), 16 (7/9), 17 (4/9) and Y (5/9). Chromosomal losses were uncommon. The chromosomal aberrations in all multifocal tumours were not identical for the same kidney or for the same patient, indicating a 'field effect' that induces multiple independent clones.

CONCLUSIONS

Although the genetic profiles of ACD-associated RCC showed some similarity to those of papillary RCC, ACD-associated RCC distinctly revealed frequent gains on chromosomes 3 and Y. ACD-associated RCC is characterized not only by its particular clinical setting and histology, but also by its unique immunohistochemical and molecular genetic profiles.

Uncommon and recently described renal carcinomas

Major consensus conferences held over a decade ago laid the foundations for the current (2004) WHO classification of renal carcinoma. Clear cell, papillary and chromophobe carcinomas account for 85-90% carcinomas seen in routine practice. The remaining 10-15% of carcinomas consist of rare sporadic and hereditary tumors, some of which had been long recognized, but many of which only emerged as distinct entities in the decade leading up to the WHO publication. Collecting-duct carcinoma is a rare, often lethal form of carcinoma. Medullary carcinoma associated with sickle cell trait, has emerged as a distinctive tumor showing some overlapping features with upper tract urothelial carcinoma. Mucinous tubular and spindle-cell carcinoma and tubulocystic carcinoma were earlier considered as patterns of low-grade collecting-duct carcinoma, but are now recognized as separate tumor entities. Carcinomas associated with somatic translocations of TFE3 and TFEB comprise a significant proportion of pediatric renal carcinomas. Oncocytoid renal carcinomas in neuroblastoma survivors was recognized as a unique tumor category in the WHO classification. Renal carcinoma associated with end-stage renal disease is now recognized as having distinct morphological patterns and behavior. In addition there is a group of rare recently described carcinomas, including clear cell papillary carcinoma, oncocytic papillary renal cell carcinoma, follicular renal carcinoma and leiomyomatous renal cell carcinoma. It behooves the surgical pathologist to not only be capable of diagnosing the common forms of renal cancer, but also to be aware of the rare types of renal carcinoma, many of which have emerged in recent years.

Renal Cell Carcinoma in Transplant Recipients with Acquired Cystic Kidney Disease

BACKGROUND

Acquired cystic kidney disease (ACKD) is a widely known renal cell carcinoma risk factor.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

An ultrasound screening of the native kidneys in all renal transplant patients of a renal outpatient clinic who received a transplant between 1970 and 1998 and presented between 1997 and 2003 (n = 916) was initiated prospectively. A total of 561 patients were screened.

RESULTS

A total of 129 (23%) patients had ACKD; 46 (8.2%) patients had complex renal cysts (Bosniak classification, category IIF to III); and eight (1.5%) patients had newly diagnosed renal cell carcinoma, seven of which were associated with ACKD (category IV). One patient had renal cell carcinoma in the transplanted kidney. Together with 19 patients of the cohort with formerly diagnosed renal cell carcinoma (18 of them associated with ACKD), the prevalence of renal cell carcinoma among all patients was 4.8%; among the patients with ACKD, it was 19.4% (without ACKD 0.5%; P = 0.0001); and among the patients with complex renal cysts (category IIF to III), it was 54.4%. The patients with ACKD were older (54 +/- 13 versus 51 +/- 14 yr; P = 0.048), more often male (65 versus 54%; P = 0.03), more often had heart disease (44 versus 29%; P = 0.001), had larger kidneys (6.9 and 6.8 cm versus 6.0 and 5.9 cm; P < 0.001), and had more calcifications (29 versus 15%; P = 0.002). Renal cell carcinoma was bilateral in 26% of cases. Tumor histology was clear cell carcinoma in 58% and papillary carcinoma in 42% of cases; one patient had both. Only one patient had a lung metastasis, and no patient died.

CONCLUSIONS

Renal cell carcinoma occurs often after renal transplantation and that especially patients with ACKD should routinely be screened. Because ACKD after renal transplantation seems to be less frequent (23%) than during dialysis treatment (30 to 90%), renal transplantation may inhibit renal cell carcinoma.

Acquired cystic disease-associated renal tumors: an immunohistochemical and fluorescence in situ hybridization study

End-stage renal disease is associated with an increased incidence of renal cell neoplasms. Among these, recent studies have identified tumors with unusual histological patterns that do not fit into the categories recognized in the current classification system. These tumors often occur in kidneys with acquired cystic disease and are composed mainly of large eosinophilic cells arranged in solid, cribriform, acinar, or papillary patterns. They also contain deposits of calcium oxalate crystals. We investigated three eosinophilic epithelial tumors arising in kidneys with acquired cystic disease from three patients. Each of the tumors was composed of large eosinophilic cells arranged in solid, acinar, or tubulocystic architecture. Deposits of calcium oxalate crystals were present in each tumor. Hale's colloidal stain showed a positive cytoplasmic reaction in one of the neoplasms. Immunohistochemistry displayed positive results for CD10 (3/3), AE1/AE3 (3/3), alpha-methylacyl-CoA racemase (2/3), CAM5.2 (2/3), and vimentin (1/3). Reactions for epithelial membrane antigen, cytokeratin 7, and high molecular weight cytokeratin (34betaE12) were negative. Fluorescence in situ hybridization analysis showed no losses or gains of chromosomes 1, 2, 6, 10, or 17 in one tumor. There were gains of chromosomes 1, 2, and 6 in two tumors. One of these tumors also showed gains of chromosome 10. Eosinophilic renal cell tumors associated with acquired cystic disease have immunophenotypes and genetic profiles distinct from the renal cell neoplasms recognized in the current classification of renal cell neoplasia, and should be considered as a distinct clinicopathologic entity in the spectrum of renal cell neoplasia.

Spectrum of epithelial neoplasms in end-stage renal disease: an experience from 66 tumor-bearing kidneys with emphasis on histologic patterns distinct from those in sporadic adult renal neoplasia

Most (up to 71%) of renal cell neoplasms occurring in patients with end-stage renal disease (ESRD), particularly with acquired cystic disease of the kidney (ACDK), have been reported to be papillary renal cell carcinoma (RCC). Our initial experience with tumors in such a setting indicated that many tumors were histologically difficult to classify into the known subtypes of RCC or had features that were different from those in sporadically occurring RCCs. In this study on 66 ESRD kidneys (52 of which showed features of ACDK) removed because tumors were detected in them, we found two major groups of RCC. Overall, there were 261 grossly identified tumors in these kidneys, and many additional tumors were observed on microscopic evaluation in some. Of the two major groups of RCCs, one consisted of tumors similar to those seen in sporadic settings (ie, clear-cell, papillary, and chromophobe RCC), and these formed the dominant mass in 12 (18%), 10 (15%), and 5 (8%) of the 66 kidneys, respectively. The other group consisted of two subtypes of RCC that appear quite unique to ESRD. The more common tumor that we have designated as "acquired cystic disease-associated RCC" was seen as the dominant mass in 24 (36%) of 66 of the kidneys, and it formed the most common tumor type among the smaller nondominant masses, as well. It was characterized by a typical microcystic architecture, eosinophilic cytoplasm with Fuhrman's grade 3 nuclei, and frequent association with intratumoral oxalate crystals. Additionally, these tumors frequently, but usually focally, exhibited papillary architecture, and clear cytoplasm. These tumors occurred only in kidneys with ACDK, and not in noncystic ESRD. The other category was "clear-cell papillary RCC of the end-stage kidneys," present as the dominant mass in 15 (23%) of the 66 kidneys and occurring in both the ACDK and noncystic ESRD. These predominantly cystic tumors showed prominent papillary architecture with purely clear-cell cytology. Immunohistochemical studies in tumors with histology similar to the known subtypes of sporadic RCC showed immunoprofiles similar to that reported in sporadically occurring tumors. The two subtypes of RCC unique to ESRD had distinctive immunoprofiles supporting their separate morphologic subcategorization. Only the acquired cystic disease-associated RCC showed lymph node metastases in 2 cases and sarcomatoid features in 2 more cases. One of the latter 2 died with widespread metastatic disease within 34 months of nephrectomy. Thus, a broad spectrum of renal cell tumors exist in ESRD, only some of which resemble the sporadic RCCs. Acquired cystic disease-associated RCC is the commonest tumor subtype in ESRD, and biologically it appears to be more aggressive than the other tumor subtypes in ESRD.

Pathological and molecular biological aspects of the renal epithelial neoplasms, up-to-date

Renal neoplasms are not necessarily high in frequency, but they are characteristic in their heterogeneity and occasional association with systemic familial tumor syndromes and phacomatoses (e.g. clear cell renal cell carcinoma and von Hippel-Lindau disease, Wilms tumor and aniridia, genitourinary malformation and mental retardation (so-called, WAGR syndrome), and angiomyolipoma and tuberous sclerosis). Physicians and pathologists should take note of these syndromes and associated renal neoplasms because they have provided important clues to elucidate the mechanism of tumorigenesis concerning cancer-suppressor genes. This review aims to present recent classification of renal parenchymal neoplasms based on their molecular biological characteristics, and future problems yet to be clarified.

Renal cell carcinoma as a cause of end-stage renal disease in the United States: patient characteristics and survival

BACKGROUND

The patient characteristics and mortality associated with renal cell carcinoma (RCC) as a cause of end-stage renal disease (ESRD) have not been characterized for a national population.

METHODS

An historical cohort study of renal cell carcinoma (RCC) was conducted from April 1, 1995, to December 31, 1999. Included were 360,651 patients in the United States Renal Data System (USRDS) who were initiated on ESRD therapy with valid causes of ESRD.

RESULTS

Of the study population, 1646 patients (0.5%) had RCC. The mean age of patients with RCC was 66.8 +/- 14.6 years versus 61.3 +/- 16.4 years for patients with other causes of ESRD (P < 0.01 by Student t test). The unadjusted 3-year survival (censored at the date of renal transplantation) of patients with RCC during the study period was 23% versus 36% in all other patients [adjusted hazard ratio (AHR), 1.10, 95% confidence interval (CI) 1.02-1.19, P = 0.019 by Cox regression]. However, patients with RCC who underwent nephrectomy (bilateral or unilateral) had significantly better survival compared to RCC patients who did not (AHR, 0.73, 95% CI, 0.63-0.85, P < 0.01), and their survival was not significantly different in comparison with nondiabetic ESRD patients. Bilateral nephrectomy (vs. unilateral) was not associated with any difference in adjusted mortality.

CONCLUSION

Among patients with ESRD, the demographics of those with RCC were similar to those of patients with RCC in the general population. Overall, patients with RCC had decreased survival compared to patients with other causes of ESRD; those who underwent nephrectomy had significantly better survival than those who did not, with survival comparable to patients with nondiabetic ESRD.

Renal cystic neoplasms and renal neoplasms associated with cystic renal diseases: pathogenetic and molecular links

Cystic renal neoplasms represent an isolated cystic mass not accompanied by cystic change of the renal parenchyma. Although cystic change may be seen in any type of renal neoplasm, a few (i.e., cystic renal cell carcinoma, cystic nephroma, cystic partially differentiated nephroblastoma, mixed epithelial and stromal tumor) are characterized by constant cystic change that may involve the entire tumor. Cystic kidney disease is characterized by cystic change, which usually involves the kidneys in a bilateral and diffuse pattern, does not create a discreet mass, and is due to hereditary or developmental conditions. Some of the cystic kidney diseases are not known to give rise to renal neoplasm; others such as autosomal polycystic kidney disease or multicystic dysplastic kidney may fortuitously coexist with renal neoplasms. Three conditions (acquired cystic kidney disease, tuberous sclerosis, and von Hippel-Lindau disease) are associated with renal neoplasms with such a high frequency that they are considered preneoplastic. This article reviews the differential diagnoses among cystic neoplasms. It also focuses on the underlying genetic and molecular mechanisms for the relationship between cystic renal diseases and renal neoplasms.