Calcium Oxalate Deposition in Renal Cell Carcinoma Associated With Acquired Cystic Kidney Disease

TFE3/TFEB altered renal cell carcinomas in end-stage renal disease setting: A single institution clinicopathological study of 4 cases

INTRODUCTION

Translocation renal cell carcinoma (tRCC) are morphologically distinct tumors having an underlying disease defining molecular alterations (commonly TFE3/TFEB gene alterations). Their occurrence in the setting of end stage renal disease (ESRD) has been rarely reported. This study was undertaken to assess the occurrence of TFE3/TFEB altered RCCs in ESRD setting at our institution.

DESIGN

By retrospective review, we searched our pathology database for tRCC in ESRD setting over a 14-year period. We analyzed and documented the clinical, histopathological, immunohistochemical, and molecular findings in these tumors.

RESULTS

Out of 223 patients of ESRD associated with RCCs, we found 4 cases of molecularly confirmed TFE3/TFEB-altered RCCs. Three of four patients were on pharmacologic immunosuppression (2 for underlying SLE and 1 for prior liver transplant). The ages ranged from 36 to 74 years (median 48 years) with an equal sex ratio. Tumors were solitary and ranged in size from 1.3 to 4.7 cm (median 2 cm). All four cases were confined to the kidney (pT1) and did not exhibit any necrosis, small vessel invasion, or sarcomatoid/rhabdoid features. The tumors exhibited characteristic morphology (solid, nested and papillary architectures with clear and eosinophilic cytoplasm in TFE3-rearranged RCCs, and biphasic morphology with basement membrane-like material in TFEB-altered RCCs). On immunohistochemistry, tumors consistently expressed cathepsin-K (3/3) & Melan-A (3/3). On molecular studies one case was confirmed via FISH study (TFEB gene rearrangement) and three cases were confirmed via RNA fusionplex (PRCC::TFE3, MED15::TFE3 and MALAT1::TFEB fusion transcripts). The median follow-up was 13 months (range 10-95 months), none of the 4 patients had any local or metastatic recurrences. One patient died of other comorbidities. Background kidney in all 4 patients exhibited variable features of ESRD.

CONCLUSION

TFE3/TFEB-altered RCCs are rarely encountered in ESRD. Morphological and immunohistochemical findings of tRCC in ESRD replicate those found in sporadic settings. To the best of our knowledge, our study is the first to identify TFEB-rearranged RCCs in an ESRD setting.

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.

Renal Cell Carcinoma in End-Stage Renal Disease: A Retrospective Study in Patients from Hungary

INTRODUCTION

End-stage renal disease (ESRD) and acquired cystic kidney disease (ACKD) are known risk factors for renal cell carcinoma (RCC). Hereby, the clinicopathological features of RCCs developed in ESRD were investigated.

METHODS

A database consisting of 34 tumors from 31 patients with ESRD among 2,566 nephrectomy samples of RCC was built. The demographic, clinical, and follow-up data along with pathological parameters were analyzed. The RCCs were diagnosed according to the current WHO Classification of Urinary and Male Genital Tumors.

RESULTS

Twenty-two tumors developed in men and 12 in women, with a median age of 56 years (range: 27-75 years). The causes of ESRD were glomerulonephritis (n = 7), hypertensive kidney disease (n = 6), autosomal dominant polycystic kidney disease (n = 6), chronic pyelonephritis (n = 4), diabetic nephropathy (n = 3), chemotherapy-induced nephropathy (n = 1), and undetermined (n = 4). ACKD complicated ESRD in 12 patients. The following histological subtypes were identified: clear cell RCC (n = 19), papillary RCC (n = 5), clear cell papillary tumor (n = 5), ACKD RCC (n = 3), and eosinophilic solid and cystic RCC (n = 2). The median tumor size was 31 mm (range: 10-80 mm), and 32 tumors were confined to the kidney (pT1-pT2). There was no tumor-specific death during the period of this study. Progression was registered in 1 patient.

CONCLUSION

In our cohort, the most common RCC subtype was clear cell RCC (55%), with a frequency that exceeded international data appreciably (14-25%). The incidence of clear cell papillary tumor and ACKD RCC (14.7% and 8.5%) was lower than data reported in the literature (30% and 40%). Our results indicate a favorable prognosis of RCC in ESRD.

Contemporary Clinical Definitions, Differential Diagnosis, and Novel Predictive Tools for Renal Cell Carcinoma

Despite significant progress regarding clinical detection/imaging evaluation modalities and genetic/molecular characterization of pathogenesis, advanced renal cell carcinoma (RCC) remains an incurable disease and overall RCC mortality has been steadily rising for decades. Concomitantly, clinical definitions have been greatly nuanced and refined. RCCs are currently viewed as a heterogeneous series of cancers, with the same anatomical origin, but fundamentally different metabolisms and clinical behaviors. Thus, RCC pathological diagnosis/subtyping guidelines have become increasingly intricate and cumbersome, routinely requiring ancillary studies, mainly immunohistochemistry. Meanwhile, RCC-associated-antigen targeted systemic therapy has been greatly diversified and emerging, novel clinical applications for RCC immunotherapy have already reported significant survival benefits, at least in the adjuvant setting. Even so, systemically disseminated RCCs still associate very poor clinical outcomes, with currently available therapeutic modalities only being able to prolong survival. In lack of a definitive cure for advanced RCCs, integration of the amounting scientific knowledge regarding RCC pathogenesis into RCC clinical management has been paramount for improving patient outcomes. The current review aims to offer an integrative perspective regarding contemporary RCC clinical definitions, proper RCC clinical work-up at initial diagnosis (semiology and multimodal imaging), RCC pathological evaluation, differential diagnosis/subtyping protocols, and novel clinical tools for RCC screening, risk stratification and therapeutic response prediction.

Calcium oxalate crystals trigger epithelial-mesenchymal transition and carcinogenic features in renal cells: a crossroad between kidney stone disease and renal cancer

Increasing evidence of association between kidney stone disease (KSD) and renal cell carcinoma (RCC) has been reported. Nevertheless, mechanism underlying such association remained unknown. Herein, we investigated the effects of calcium oxalate monohydrate (COM), a major crystalline component causing KSD, on induction of carcinogenic features in non-cancerous renal cells. COM crystals induced morphological changes from epithelial to fibroblast-like spindle shape. Additionally, COM increased spindle index and mesenchymal markers (fibronectin and vimentin) but declined epithelial markers (E-cadherin and zonula occludens-1). Moreover, COM down-regulated ARID1A, a tumor suppressor gene recently reported to be reversely associated with RCC, at both mRNA and protein levels. COM also down-regulated other RCC-related tumor suppressor genes, PTEN and VHL, but up-regulated oncogene TPX2. Finally, COM enhanced invading capability, cell-aggregate formation, chemoresistance to cisplatin, and secretion of an angiogenic factor (VEGF). These data indicate that COM crystals trigger epithelial-mesenchymal transition (EMT) and several carcinogenic features in the non-cancerous renal cells. These mechanisms may explain and strengthen the association between KSD and RCC.

Acquired cystic disease subtype renal cell carcinoma (ACD-RCC): prevalence and imaging features at a single institution

PURPOSE

Acquired cystic kidney disease (ACKD) is commonly seen in patients with end-stage renal disease (ESRD), and patients with ACKD have an increased risk of renal cell carcinoma (RCC). Acquired cystic disease-associated RCC (ACD-RCC) was incorporated into the 2016 World Health Organization Classification. This study aims to describe the imaging features of ACD-RCC, which are not well reported previously.

METHODS

Retrospective review of patients with ACKD who underwent total nephrectomy for concern of a renal mass between 2016 and 2021 yielded 122 nephrectomies in 107 patients. Pathology reports were searched for type and subtype of mass. In ACD-RCC subtypes, imaging studies were evaluated for modality and contrast enhancement (CE). Imaging findings assessed included cystic/solid nature, unenhanced CT (NECT) attenuation, enhancement characteristics [non-enhancing (< 10 HU difference), equivocal (10-20 HU), enhancing (> 20 HU)], subjective MRI enhancement, T1 and T2 signal intensity, restricted diffusion, ultrasound (US) echogenicity, and subjective CEUS enhancement.

RESULTS

148 masses were identified, 122 (82%) of which were malignant and 26 (18%) benign. The three most common tumors were clear cell RCC (n = 47), papillary RCC (n = 35), and ACD-RCC (n = 21). Of the 21 cases of ACD-RCC, 16 had preoperative imaging: CT (15: 6 NECT only, 2 CECT only, 7 combined NECT and CECT), MRI (4), CEUS (5). Ten of these tumors were solid/mostly solid and 6 mixed cystic/solid. On NECT, the average attenuation was 35 HU (range 13-52). Of those with multiphasic CTs, 1 was non-enhancing, 3 were equivocal, and 3 enhanced. All 3 masses imaged with CE-MRI showed enhancement. All 4 tumors evaluated by MRI demonstrated T2 hypointensity and restricted diffusion. All five masses enhanced on CEUS.

CONCLUSION

ACD-RCC subtype was the third most common renal neoplasm in ACKD patients. Our findings found that no single imaging feature is pathognomonic for ACD-RCC. However, ACD-RCCs are typically solid masses with most demonstrating equivocal or mild enhancement on CT. T2 hypointensity and restricted diffusion were the most common MRI features.

Renal Cell Carcinoma in End-Stage Renal Disease: A Review and Update

Renal cell carcinoma (RCC) occurring in the setting of end-stage renal disease (ESRD) shows unique clinicopathological characteristics. The two most frequent types of ESRD-associated RCC are acquired cystic kidney disease-associated renal cell carcinoma (ACKD-RCC) and clear-cell papillary renal cell carcinoma (ccpRCC). Other types of RCC also occur in ESRD, albeit with different frequencies from the non-ESRD general population. The histological features of RCC do not vary in the setting of ESRD vs. non-ESRD, yet other findings, such as multifocality and multiple tumor types, are more frequent in ESRD. Studies have generated novel and important knowledge of the etiology, epidemiology, diagnosis, treatment, immunophenotype, and molecular characteristics of ESRD-associated RCC. Knowledge of these data is important for both pathologists and other physicians who may encounter ESRD patients with RCC. This review presents a comprehensive summary and update of the literature on RCC in ESRD, with a focus on the two most frequent types, ACKD-RCC and ccpRCC.

Papillary Renal Cell Carcinoma With Microcystic Architecture Is Strongly Associated With Extrarenal Invasion and Metastatic Disease

Papillary renal cell carcinoma (PRCC) is well-recognized as a morphologically and molecularly heterogenous group of kidney tumors with variable clinical behavior. Our goal was to analyze a unique histologic pattern of PRCC we have observed in routine practice to evaluate for potential clinical significance or distinct molecular signature. We identified 42 cases of PRCC showing a morphologically distinct architecture characterized by numerous epithelial-lined cysts containing the papillary tumor (herein called "microcysts"), which are typically separated by fibrous stroma. Of the initial 42 case test set with microcystic features, 23 (55%) were stage pT3a or higher. Most tumors had strong and diffuse cytoplasmic immunoreactivity for CK7 (93%, 37/40) and AMACR (100%, 40/40). Fumarate hydratase staining was retained in all cases tested (39/39). We performed next-generation sequencing on 15 of these cases with available tissue and identified chromosomal alterations commonly reported in historically "type 1" PRCC, notably multiple chromosomal gains, particularly of chromosomes 7 and 17, and MET alterations. However, alterations in pathways associated with more aggressive behavior (including SETD2, CDKN2A, and members of the NRF pathway) were also identified in 6 of 15 cases tested (40%). Given this molecular and immunophenotypic data, we subsequently reviewed an additional group of 60 consecutive pT2b-pT3 PRCCs to allow for comparisons between cases with and without microcysts, to assess for potential associations with other recently described histologic patterns (ie, "unfavorable architecture": micropapillary, solid, and hobnail), and to assess interobserver reproducibility for diagnosing architectural patterns and grade. Of the total combined 102 PRCCs, 67 (66%) had microcystic architecture within the intrarenal component but were commonly admixed with other patterns (39% had micropapillary, 31% solid, and 31% hobnail). Twenty-seven cases (26%) had metastatic disease, and 24 of these 27 (89%) had microcystic architecture in the intrarenal tumor. Within the pT3 subset, 21 of 22 cases with metastases (95%) had extrarenal invasion as either individual microcysts in renal sinus fat or aggregates of microcysts bulging beyond the confines of the capsule. Backward elimination and stepwise regression methods to detect features significantly associated with adverse outcome identified solid architecture (hazard ratio [HR]: 6.3; confidence interval [CI]: 2.1-18.8; P=0.001), hobnail architecture (HR: 5.3; CI: 1.7-16.7; P=0.004), and microcystic architecture at the tumor-stromal interface (HR: 4.2; CI: 1.1-16.7; P=0.036) as strongest. Of architectural patterns and grade, the microcystic pattern had a substantial interobserver agreement (κ score=0.795) that was highest among the 6 observers. In summary, PRCCs with microcystic architecture represents a subset of historically "type 1" PRCC with a predilection for morphologically distinctive extrarenal involvement and metastatic disease. Microcysts co-vary with other "unfavorable" architectural patterns also associated with higher risk for aggressive disease (ie, micropapillary, hobnail, and solid), but microcysts were more common and have superior interobserver reproducibility. These findings suggest that microcystic PRCC should be recognized as a potentially aggressive histologic pattern of growth in PRCC.

CT features of acquired cystic kidney disease-associated renal cell carcinoma

PURPOSE

Acquired cystic kidney disease-associated renal cell carcinoma (ACKD-RCC) is a relatively recently described entity with scarce literature describing its imaging appearance (1, 2). The purpose of this study was to determine typical and potentially unique features of ACKD-RCC on CT scan that could aid lesion identification.

MATERIALS AND METHODS

A retrospective review of the CT scans of 24 patients with 29 histologically proven ACKD-RCC lesions was performed. Imaging features were recorded based on consensus readings of two radiologists.

RESULTS

Tumors ranged in size from 1.2 to 5 cm. Nineteen lesions were right-sided and 10 left-sided. Nineteen lesions were exophytic. One patient had bilateral lesions and three patients had multiple lesions in the same kidney. All lesions had well-defined margins with 21 round, 7 lobulated and 1 crescentic in shape. On non-enhanced exam 4 lesions were hypodense, 16 iso-dense and 9 hyperdense; 5 had gross calcifications. Twenty two patients had contrast-enhanced CT exams, with 13 lesions demonstrating homogeneous enhancement (solid pattern) and 14 having inhomogeneous enhancement (cystic or mixed solid and cystic pattern). Only 1 patient had metastatic disease. Eight patients had a history of renal transplants.

CONCLUSION

ACKD-RCCs are well-defined lesions of variable size that are almost always rounded and most often exophytic. They occasionally have calcifications and are not uncommonly hyperdense on non-enhanced exam. They are most often iso-dense on non-enhanced exam and can be solid, cystic or mixed in attenuation on enhanced exam.

Acquired cystic disease-associated renal cell carcinoma: A clinicopathologic study of eight tumors with clinical follow-up

Acquired cystic disease-associated renal cell carcinoma (ACD-RCC) is the major RCC subtype in patients with end-stage renal disease, specifically those with ACD on dialysis. Three patients with a total of eight tumors have been selected. The aim of this study was to analyze clinicopathologic, immunohistochemical, and prognostic features of eight ACD-RCCs. Three patients with end-stage renal disease (ESRD) were in the age range of 34-45 years and being treated with hemodialysis. All eight tumors were resected by radical nephrectomy. Two patients had a single ACD-RCC, while one patient had bilateral and multifocal ACD-RCCs. Microscopically, combinations of architectural patterns were identified in all tumors. Intracytoplasmic and intraluminal vacuoles, eosinophilic granular cytoplasm, and prominent nucleoli were universal characteristics of these tumors. Atypical cysts were present in three out of four resected kidneys. Immunohistochemistry (IHC) staining revealed all tumors were strongly and diffusely positive for pan-cytokeratin and α-methylacyl-CoA racemase and variably positive for CK7, CD10, PAX8, EMA, vimentin, cytokeratin, high molecular weight cytokeratin (CK HMW). All cases were negative for Napsin A, CK20, CD117, and CD57. After an average follow-up of 27.5 months (range 3-54 months), all our patients are alive without neoplastic (metastatic or recurrent) disease. Our study supports the finding that ACD-RCC has specific morphologic features and a broad spectrum of architectural patterns. We have found that the immunoprofile of ACD-RCC is distinct from that in other RCCs; however, nonspecific and interpretation of microscopic features in the context of the clinical history can aid the diagnosis. We confirm also the favorable prognosis in ACD-RCC.

Comparable survival outcome between acquired cystic disease associated renal cell carcinoma and clear cell carcinoma in patients with end-stage renal disease: a multi-institutional central pathology study

Acquired cystic disease (ACD) associated renal cell carcinoma (RCC) is designated as a new subtype unique to patients with end-stage renal disease (ESRD) according to the 2016 World Health Organization (WHO) classification. However, the oncological outcomes of the prognostic factors for patients with this subtype are not fully understood. In the present study, we compared the survival of ACD associated RCC patients who underwent nephrectomy with that of patients with other histological subtypes who developed ESRD. Over 378 patients who underwent nephrectomy at three Japanese institutes between 1987 and 2016 were included in this study. A central pathologist reviewed the sections from all patients according to the 2016 WHO classification. The central pathological review showed a clear cell subtype in 165 patients (43.6%), ACD associated RCC in 112 (29.6%), papillary in 61 (16.1%), and others in 40 (10.7%). The proportion of patients with pathological stage 1 was extremely high in both clear cell and ACD associated RCC cohorts (86.6%, 85.7%). The cancer specific survival (CSS) and recurrence free survival rates of patients with ACD associated RCC were comparable with those with clear cell carcinoma and significantly better than those with the papillary subtype. The factors predictive of unfavourable outcomes were long dialysis duration, tumour size, pathological stage, grade 4 tumour, and the presence of lymphovascular invasion or a sarcomatoid component. Patients with a pre-operative dialysis duration of 20 years or longer showed a significantly worse CSS than other patients, probably owing to sarcomatoid differentiation and stage migration during the advanced stages. In conclusion, this study included the largest number of patients with ACD associated RCC, showing a survival similar to that of clear cell histology patients with ESRD, except for the rarity of late recurrence. ACD associated RCC was not as indolent as initially recognised when patients were on long term dialysis.

Comprehensive Clinicopathologic Analyses of Acquired Cystic Disease-associated Renal Cell Carcinoma With Focus on Adverse Prognostic Factors and Metastatic Lesions

Acquired cystic disease of kidney-associated renal cell carcinoma (ACD-RCC) is a distinct subtype of renal cell carcinoma with unique morphologic and clinicopathologic features. Generally, ACD-RCC is regarded as an indolent tumor; however, prognostic and outcomes data have been conflicted by the limited and relatively low number of cases with patient follow-up or adverse events. In this study, we focused on the histology of metastatic lesions and identifying prognostic factors associated with metastatic progression. From 32 cases in the cohort, 9 patients had metastasis [ACD-RCC (M+)] and 23 patients were without metastasis [ACD-RCC (M-)]. The median age of patients was 52 years; right side, n=10; left side, n=18; bilateral, n=4; median tumor size=2.6 cm; median hemodialysis duration=17 y; and the median duration of follow-up was 50 mo. Immunohistochemistry showed ACD-RCC to be racemase positive and CK7 negative to focally positive within tumor cells, with consistent positivity for renal histogenesis-associated markers (PAX8 and RCC antigen); S100A1 was a less reliable marker at metastatic sites. All metastatic ACD-RCC except 2 cases involved lymph nodes (para-aortic, renal hilar, subclavicular). Overall, 6/9 (67%) had visceral metastasis to sites including lung (n=3), liver (n=3), bone (n=5), stomach (n=1), and brain (n=1). In total, 5/9 (56%) metastatic tumors had distinctive cystic growth pattern at the metastatic site; intriguingly metastatic tumors had intrametastatic oxalate crystal deposition, a pathognomonic feature associated with primary tumors. Four of nine (44%) patients with ACD-RCC (M+) had fatal outcomes due to metastatic disease. Clinically significant adverse prognostic features associated with metastasis [median follow-up 47 mo, ACD-RCC (M+) vs. ACD-RCC (M-), 50 mo] included: duration of hemodialysis (≥20 vs. <20 y, P=0.0085) and tumor necrosis (P=0.049). Because of sufficient overlap between these parameters, the study was not able to identify parameters that would be reliable in further management strategies, in clinical settings. Our data indicate that ACD-RCC is a tumor which has distinct metastatic potential with nodal and visceral tropism and proclivity for cystic morphology at metastatic sites; this is the first report of the presence of oxalate crystals in metastatic tumors. Our data suggest that ACD-RCC patients with prolonged hemodialysis and tumoral coagulative necrosis require additional surveillance in view of the association of these parameters with metastatic progression.

Cytomorphologic analysis of clear cell papillary renal cell carcinoma: Distinguishing diagnostic features

BACKGROUND

Clear cell papillary renal cell carcinoma (CCPRCC) shares histomorphologic and immunophenotypic features with clear cell RCC (CCRCC) and papillary RCC (PRCC).

METHODS

We compared the cytomorphology, immunoprofile, and clinical management of CCPRCC (n = 18), CCRCC (n = 20), and PRCC (n = 18).

RESULTS

Useful cytomorphologic features for comparing CCPRCC with CCRCC include 3-dimensional clusters (72% vs 0%), papillae (50% vs 0%) and sheets (22% vs 70%), vasculature (papillary vs traversing), naked nuclei (17% vs 100%), prominent nucleoli (0% vs 65%), and amount of cytoplasm (small vs large). Useful cytomorphologic features for comparing CCPRCC with PRCC include sheets (22% vs 61%), naked nuclei (17% vs 67%), nuclear grooves (5% vs 67%) and inclusions (17% vs 67%), and pigmented cytoplasm (17% vs 83%). At on-site evaluation, 16 of 18 (86%) CCPRCC specimens were deemed adequate, with suspicion for CCPRCC in 5 of 16 (31%) cases. Core histology of CCPRCC showed low-grade malignant cells in nests (67%), tubules (100%), and papillae (72%), frequently in myxohyaline stroma (67%). Immunostains demonstrated expression of cytokeratin 7 (CK7; 100%), carbonic anhydrase IX (CA IX; 100%, cup-like), CD10 (53%, reverse cup-like), and α-methylacyl-CoA racemase (AMACR; 35%). Among 18 CCPRCC patients, 9 (50%) underwent nephrectomy, 5 (28%) underwent cryo-ablation, and 4 (22%) were under surveillance with serial imaging.

CONCLUSION

Certain morphologic features represent diagnostic criteria of CCPRCC in cytology specimens and help distinguish CCPRCC from CCRCC and PRCC. Immunostaining patterns with CK7, CA IX, CD10, and AMACR can confirm the diagnosis. Delineating CCPRCC from more biologically aggressive RCC types in cytology specimens enhances presurgical and clinical management of patients given CCPRCC's low-grade, indolent behavior.

[Kidney Cysts and Cystic Nephropathies in Children - A Consensus Guideline by 10 German Medical Societies]

This consensus-based guideline was developed by all relevant German pediatric medical societies. Ultrasound is the standard imaging modality for pre- and postnatal kidney cysts and should also exclude extrarenal manifestations in the abdomen and internal genital organs. MRI has selected indications. Suspicion of a cystic kidney disease should prompt consultation of a pediatric nephrologist. Prenatal management must be tailored to very different degrees of disease severity. After renal oligohydramnios, we recommend delivery in a perinatal center. Neonates should not be denied renal replacement therapy solely because of their age. Children with unilateral multicystic dysplastic kidney do not require routine further imaging or nephrectomy, but long-term nephrology follow-up (as do children with uni- or bilateral kidney hypo-/dysplasia with cysts). ARPKD (autosomal recessive polycystic kidney disease), nephronophthisis, Bardet-Biedl syndrome and HNF1B mutations cause relevant extrarenal disease and genetic testing is advisable. Children with tuberous sclerosis complex, tumor predisposition (e. g. von Hippel Lindau syndrome) or high risk of acquired kidney cysts should have regular ultrasounds. Even asymptomatic children of parents with ADPKD (autosomal dominant PKD) should be monitored for hypertension and proteinuria. Presymptomatic diagnostic ultrasound or genetic examination for ADPKD in minors should only be done after thorough counselling. Simple cysts are very rare in children and ADPKD in a parent should be excluded. Complex renal cysts require further investigation.

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.

Bilateral and Multifocal Acquired Cystic Disease-Associated Renal Cell Carcinomas in Patient With End-Stage Renal Disease Caused by Systemic Lupus Erythematosus

The disease entity of acquired cystic disease-associated renal cell carcinoma (ACD-RCC) has been recently incorporated into the international renal tumor classification. We performed a clinicopathologic study of a patient with bilateral and multifocal ACD-RCCs. The patient received long-term hemodialysis in the end-stage renal disease caused by systemic lupus erythematous. First left-sided nephrectomy and after 6 months right-sided nephrectomy was performed. None of the preoperative radiologic examinations revealed lesions suspected of malignancy. All of the 6 tumors were incidentally found on grossing radical nephrectomy specimens. Histologically, tumors consisted of a variety of growth patterns (including papillary and cribriform) of neoplastic cells with granular eosinophilic cytoplasm and intratumoral oxalate crystals. Neoplastic cells were positive for AMACR, CK AE1/AE3, and CD10; focally positive for CK7; and negative for PAX8. Seven months after the first nephrectomy, the patient still receives dialysis. There was no evidence of lymph node or distant metastases.

Pathologic characterization of renal epithelial neoplasms arising in nonfunctioning kidneys

Nonfunctioning kidneys secondary to various etiologies display different histopathological features. Studies focused on incidence and types of renal neoplasms using the new World Health Organization and International Society of Urological Pathology classification system in various types of nonfunctioning kidneys are very limited. We identified 311 nephrectomies of nonfunctioning kidneys and categorized them into 5 categories: acquired cystic kidney disease (ACKD, n = 61); end-stage renal disease, nonspecific (ESRD, n = 63); adult polycystic kidney disease (APKD, n = 49); failed transplant kidney (FTK, n = 96); and those caused by obstructive conditions in the kidney (OCK, n = 42). ACKD (70%) and ESRD (43%) had higher cancer incidences than the other 3 groups (APKD = 2%, FTK = 0%, and OCK = 5%). Besides clear cell renal cell carcinoma (RCC) and papillary RCC, clear cell papillary RCC had a much higher incidence within ACKD patients (13/61) compared to other groups. ACKD-associated RCC was only identified in ACKD patients. ACKD patients had significantly longer dialysis duration compared to ESRD, APKD, and FTK. Although they had similar risk for clear cell RCC and papillary RCC, ACKD patients had a much higher risk for ACKD-associated RCC and clear cell papillary RCC than ESRD patients. Although most RCCs arising in these nonfunctioning kidneys were early pT1 stage, 6 ACKD patients and 3 ESRD patients had higher-stage diseases, which can be fatal if not treated appropriately. Therefore, precise clinicopathological classification of these nonfunctioning kidneys is important for predicting kidney cancer risk. These results indicate the need for active monitoring of the patients with high-risk nonfunctioning kidney diseases and appropriate surgical treatment when necessary.

Five decades of urologic pathology: the accelerating expansion of knowledge in renal cell neoplasia

Those who are knowledgeable in cosmology inform us that the expansion of the universe is such that the velocity at which a distant galaxy is receding from the observer is continually increasing with time. We humbly paraphrase that as "The bigger the universe gets, the faster it gets bigger." This is an interesting analogy for the expansion of knowledge in the field of renal tumor pathology over the past 30 to 50 years. It is clear that a multitude of dedicated investigators have devoted incalculable amounts of time and effort to the pursuit of knowledge about renal epithelial neoplasms. As a consequence of the contributions of numerous investigators over many decades, the most recent World Health Organization classification of renal neoplasms includes about 50 well defined and distinctive renal tumors, as well as various miscellaneous and metastatic tumors. In addition, a number of emerging or provisional new entities are under active investigation and may be included in future classifications. In this review, we will focus on a number of these tumors, tracing as accurately as we can the origins of their discovery, relating relevant additions to the overall knowledge base surrounding them, and in some instances addressing changes in nomenclature.

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.

New entities, new technologies, new findings: A review of the cytologic features of recently established subtypes of renal cell carcinoma

Several new renal tumor types with distinctive pathologic, epidemiologic, and genetic signatures have recently been adopted in the fourth edition of the World Health Organization classification. In succeeding years, the cytologic features of most of these new types have been described, adding to the trend of increasing diagnostic accuracy for most common renal cell carcinoma subtypes and the important diagnostic role of cytologic sampling in the management and personalization of therapy. The current article reviews the cytologic findings from these recently established renal cell carcinoma subtypes. Emphasis is placed on cytologic diagnostic clues, confirmatory ancillary testing, salient differential diagnoses, and challenges that can be encountered in an attempt to render accurate interpretations in small samples.

Comparison of Renal Anastomosing Hemangiomas in End-Stage and Non–End-Stage Kidneys: A Meta-Analysis With a Report of 2 Cases

Background. Renal anastomosing hemangioma (RAH) is a very rare distinct entity composed of anastomosing sinusoidal (spleen-like) capillary-sized vessels lined by flat or hobnail endothelial cells. Most of the published cases of RAH occurred in the setting of end-stage renal disease (ESRD). Methods. We present 2 cases of RAH in ESRD along with a literature review. We compared clinicopathologic features of RAHs in end-stage and non–end-stage kidneys. A meta-analysis was conducted with PubMed and a manual search through references of relevant publications. Individual patient data gathered from the literature were used in the analysis. Results. Our systematic review revealed 49 RAHs, including our 2 cases. Thirty-two (65.3%) cases were in ESRD, only 17 (34.7%) were in patients with non-ESRD. RAHs in ESRD were in younger patients, smaller in size, multifocal, and seen more with renal epithelial neoplasms when compared with RAHs in non-ESRD ( P < .05). Extramedullary hematopoiesis was seen mostly in RAHs in ESRD kidneys (85% vs 41.7%) ( P = .018). Follow-up data were available for 25 cases with a mean follow-up of 24.58 ± 38.54 months. Recurrence, metastasis, or death have never been described related to RAH in any patients. Conclusions. In conclusion, RAHs are rare and mostly arise in kidneys with end-stage damage. RAHs in ESRD and non-ESRD differ in terms of clinicopathologic features.

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.

Renal cell carcinoma in kidney allografts: histologic types, including biphasic papillary carcinoma

Kidney transplant recipients are at increased risk for malignancy, with about 5% incidence of cancer in native end-stage kidneys. Carcinoma in the renal allograft is far less common. Prior studies have demonstrated a propensity for renal cell carcinomas (RCCs) of papillary subtypes in end-stage kidneys, and perhaps in allograft kidneys, but most allograft studies lack detailed pathologic review and predate the current classification system. We reviewed our experience with renal carcinoma in kidney allografts at 2 academic centers applying the International Society of Urological Pathology classification, informed by immunohistochemistry. The incidence of renal allograft carcinoma was about 0.26% in our population. Of 12 allograft carcinomas, 6 were papillary (50%), 4 were clear cell (33%), 1 was clear cell (tubulo)papillary, and 1 chromophobe. Two of the papillary carcinomas had distinctive biphasic glomeruloid architecture matching the newly named "biphasic squamoid alveolar" pattern and were difficult to classify on core biopsies. The 2 cell types had different immunophenotypes in our hands (eosinophilic cells: RCC-/CK34betaE12+ weight keratin +/cyclin D1+; clear cells: RCC+/cytokeratin high molecular weight negative to weak/cyclin D1-). None of the patients experienced cancer recurrences or metastasis. Our study confirms the predilection for papillary RCCs in kidney allografts and highlights the occurrence of rare morphologic variants. Larger studies are needed with careful pathologic review, which has been lacking in the literature.

Molecular genetics and immunohistochemistry characterization of uncommon and recently described renal cell carcinomas

Renal cell carcinoma (RCC) compromises multiple types and has been emerging dramatically over the recent several decades. Advances and consensus have been achieved targeting common RCCs, such as clear cell carcinoma, papillary RCC and chromophobe RCC. Nevertheless, little is known on the characteristics of several newly-identified RCCs, including clear cell (tubulo) papillary RCC, Xp11 translocation RCC, t(6;11) RCC, succinate dehydrogenase (SDH)-deficient RCC, acquired cystic disease-associated RCC, hereditary leiomyomatosis RCC syndrome-associated RCC, ALK translocation RCC, thyroid-like follicular RCC, tubulocystic RCC and hybrid oncocytic/chromophobe tumors (HOCT). In current review, we will collect available literature of these newly-described RCCs, analyze their clinical pathologic characteristics, discuss their morphologic and immunohistologic features, and finally summarize their molecular and genetic evidences. We expect this review would be beneficial for the understanding of RCCs, and eventually promote clinical management strategies.

Emerging Entities in Renal Neoplasia

This article reviews emerging entities in renal epithelial neoplasia, including tubulocystic carcinoma, clear-cell-papillary renal cell carcinoma (RCC), thyroid-like follicular RCC, ALK-related RCC, translocation RCC, acquired cystic disease-related RCC, succinate dehydrogenase-deficient RCC, and hereditary leiomyomatosis-RCC syndrome-associated RCC. Many of these rarer subtypes of RCC were recently studied in more depth and are included in the upcoming version of the World Health Organization classification of tumors. Emphasis is placed on common gross and morphologic features, differential diagnoses, use of ancillary studies for making accurate diagnoses, molecular alterations, and predicted biologic behavior based on previous studies.

Acquired cystic disease-associated renal cell carcinoma with a focal sarcomatoid component: Report of a case showing more pronounced polysomy of chromosomes 3 and 16 in the sarcomatoid component

Acquired cystic disease (ACD)-associated renal cell carcinoma (RCC) has recently been established. Herein we report the sixth case of ACD-associated RCC with a sarcomatoid change. The patient was a 77-year-old man who regularly underwent hemodialysis for 14 years due to chronic renal failure resulting from IgA nephropathy. On computed tomography, a large right RCC was observed with contrast enhancement in the arterial phase. A nodular protrusion into the perirenal fat was detected. Right nephrectomy was performed under laparoscopy. Surgically resected specimens revealed a tan-to-yellow tumor (95 × 75 × 55 mm) with a whitish nodule (20 × 15 × 15 mm) invading into the perirenal fat. Histopathologically, the large carcinoma component of the tumor displayed a cribriform or microcystic growth pattern with deposition of oxalate crystals. The whitish nodule corresponded to the sarcomatoid component, and the spindled and pleomorphic tumor cells showed diffuse positivity of p53 on immunohistochemistry. Fluorescence in situ hybridization revealed trisomy of chromosomes 3 and 16 in the carcinoma component, as was expected from the literature. In addition, increased polysomy of these chromosomes was also observed in the sarcomatoid component. This finding may be related to the development of the sarcomatoid component along with the TP53 mutation.

Diagnostic approach to eosinophilic renal neoplasms

CONTEXT

Eosinophilic renal neoplasms include a spectrum of solid and papillary tumors ranging from indolent benign oncocytoma to highly aggressive malignancies. Recognition of the correct nature of the tumor, especially in biopsy specimens, is paramount for patient management.

OBJECTIVE

To review the diagnostic approach to eosinophilic renal neoplasms with light microscopy and ancillary techniques.

DATA SOURCES

Review of the published literature and personal experience.

CONCLUSIONS

The following tumors are in the differential diagnosis of oncocytic renal cell neoplasm: oncocytoma, chromophobe renal cell carcinoma (RCC), hybrid tumor, tubulocystic carcinoma, papillary RCC, clear cell RCC with predominant eosinophilic cell morphology, follicular thyroid-like RCC, hereditary leiomyomatosis-associated RCC, acquired cystic disease-associated RCC, rhabdoid RCC, microphthalmia transcription factor translocation RCC, epithelioid angiomyolipoma, and unclassified RCC. In low-grade nonpapillary eosinophilic neoplasms, distinction between oncocytoma and low-grade RCC mostly rests on histomorphology; however, cytokeratin 7 immunostain may be helpful. In high-grade nonpapillary lesions, there is more of a role for ancillary techniques, including immunohistochemistry for cytokeratin 7, CA9, CD10, racemase, HMB45, and Melan-A. In papillary eosinophilic neoplasms, it is important to distinguish sporadic type 2 papillary RCC from microphthalmia transcription factor translocation and hereditary leiomyomatosis-associated RCC. Histologic and cytologic features along with immunohistochemistry and fluorescence in situ hybridization tests for TFE3 (Xp11.2) and TFEB [t(6;11)] are reliable confirmatory tests. Eosinophilic epithelial neoplasms with architecture, cytology, and/or immunoprofile not qualifying for either of the established types of RCC should be classified as unclassified eosinophilic RCC and arbitrarily assigned a grade (low or high).

Recent classification of renal epithelial tumors

The recent classification of renal tumors is based on genetic evidence as well as on histologic features. Malignant tumor includes clear cell renal carcinoma (RCC), multilocular cystic RCC, papillary RCC, chromophobe RCC, carcinoma of the collecting duct of Bellini, renal carcinoma associated with Xp11.2 translocations/TFE3 gene fusions and mucinous tubular and spindle cell carcinoma. Benign tumor is subdivided into papillary adenoma, renal oncocytoma and metanephric adenoma. Recently, new disease entities such as acquired cystic disease-associated RCC, clear cell papillary RCC and renal carcinoma with t(6;11)(p21:q12) have been discovered. In this article, we briefly review and introduce the clinical, morphological and genetic features of these tumor entities.

Acquired cystic disease-associated renal cell carcinoma: further characterization of the morphologic and immunopathologic features

Acquired cystic disease-associated renal cell carcinoma (ACD-RCC) is a subtype of renal cell carcinoma (RCC) with unique morphologic features found exclusively in the background of end-stage renal disease. We analyzed the clinicopathologic features and immumoreactive profiles of 12 cases of ACD-RCC to further characterize this recently recognized entity. Review of histologic slides was performed in conjunction with immunohistochemical staining directed to the contemporary diagnostic antibodies and the putative target therapy-related markers. Histologically, the tumors showed characteristic inter-or intracellular microlumens and eosinophilic tumor cells. Intratumoral hemosiderin deposition and degenerating foamy tumor cells were consistent findings which were not previously described. Immunohistochemically, all the tumors were positive for alpha-methylacyl-CoA-racemase, CD10, pan-cytokeratin, PTEN (phosphatase and tensin homolog deleted on chromosome 10) and c-met, while negative for carbonic anhydrase-9, CD57, CD68, c-kit, pax-2, platelet-derived growth factor receptor (PDGFR)-α or vascular endothelial growth factor receptor (VEGFR)-2. Heterogenous staining was found for CK7 and kidney-specific cadherin. Positive reaction to c-met suggests its utility as a plausible therapeutic target in ACD-RCC. Thus, we present the unique morphologic and immunopathologic features of ACD-RCC, which may be helpful in both diagnostic and therapeutic aspects.

Malignant tumors in patients with end stage renal failure undergoing renal replacement therapy

In 1975 Matas and co-workers were the first in the world literature to show an increased risk of malignant tumor occurrence in the group of hemodialyzed patients and kidney transplant recipients. The report is an analysis of world literature from the last 35 years in reference to epidemiology as well as the profile of screening tests and diagnostic methods related to malignant tumors in the population with end stage renal disease, especially hemodialyzed patients.

Spectrum of preneoplastic and neoplastic cystic lesions of the kidney

CONTEXT

Cystic lesions of the kidney may be accompanied by a range of neoplasms with distinct prognoses and future risks of developing additional tumors. In addition, some renal tumors, with or without accompanying renal cysts, may show a prominent cystic component. In the adult population, neoplasms occurring in a background of renal cystic diseases and cystic renal neoplasms often pose diagnostic challenges because of their many overlapping features.

OBJECTIVE

To review the clinicopathologic characteristics of common entities in the spectrum of neoplastic and potential preneoplastic cystic lesions encountered in adults, with an emphasis on renal cystic diseases associated with tumor development and on renal neoplasms with predominantly cystic morphology.

DATA SOURCES

The relevant English-language literature was reviewed, accompanied by the authors' experience at their practicing institution.

CONCLUSIONS

The presence of multiple renal cysts, both acquired and syndromic, can be associated with a variety of renal tumors. The morphology of the cysts and associated tumor types can help predict the genetic or acquired basis of the lesions, and particularly in specimens with no accompanying pertinent clinical history, such potential associations should be suggested in surgical pathology reports.

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 carcinomas in end-stage kidneys: a clinicopathological study with emphasis on clear-cell papillary renal-cell carcinoma and acquired cystic kidney disease-associated carcinoma

Clear-cell papillary renal-cell carcinoma (CCPC) and acquired cystic kidney disease-associated carcinoma (ACDAC) are neoplasms with distinct morphological characteristics that behave less aggressively than conventional renal-cell carcinomas. End-stage kidney specimens from 61 patients (47 males and 14 females) with 109 renal-cell carcinomas were selected. Papillary renal-cell carcinoma was the most common malignancy (61/109, 56%), followed by CCPC (20/109, 18%). The CCPC showed a papillary or tubular/solid architecture, clear cytoplasm, low nuclear grade, and a distinct immunohistochemical profile (RCC-, vimentin+, CK7+, p504S-). ACDAC displayed a variety of architectural patterns, eosinophilic cytoplasm, high nuclear grade, intratumoral calcium oxalate deposits, and an immunohistochemical profile similar to type 2 papillary renal-cell carcinoma (RCC+, vimentin+, CK7-/+, p504S+). Less than 5% (3/69) of pathologically staged renal-cell carcinomas in end-stage kidneys presented with lymphogenous and/or hematogenous metastases.

Acquired cystic disease-associated renal cell carcinoma with sarcomatoid change and rhabdoid features

Acquired cystic disease (ACD)-associated renal cell carcinoma (RCC) is a recently described entity. To the best of our knowledge, there are no reports of ACD-associated RCC with sarcomatoid and rhabdoid changes. In this article, we present the first case of such a tumor. A 56-year-old Japanese man has received long-term hemodialysis and had a history of right renal cancer. Following the discovery of metastatic cancer in the thoracic wall, detailed imaging studies revealed a mass in the left kidney. The histologic examination of the left renal tumor showed ACD-associated RCC with sarcomatoid change and rhabdoid features. Immunohistochemically, intracytoplasmic globular inclusions in rhabdoid cells were positive for vimentin and cytokeratin CAM5.2. The G-band karyotype showed the following changes: 46, X, +X. -Y[1]/43, idem, add(2)(q31), -6, -9, -14, -15, +16, -22, +mar1[6]/46, XY[2]/abnormal cell[11]. In conclusion, pathologists and urologists should be aware that rhabdoid features may occur in ACD-associated RCC and that the loss of chromosomes 9 and 14 may occur during the process of sarcomatoid change in ACD-associated RCC.

Renal cell carcinomas in haemodialysis patients: does haemodialysis duration influence pathological cell types and prognosis?

BACKGROUND

It is well known that renal cell carcinoma (RCC) is one of the most important complications in haemodialysis (HD) patients. However, the influence of HD duration on the development of RCCs has not yet been described. This study sought to determine whether HD duration is related to pathological RCC types and to prognosis.

METHODS

We examined 69 patients having HD (73 kidneys) who underwent radical nephrectomy for renal tumours between 1991 and 2008. We divided the patients into three groups according to the duration of HD (< 10 years, between 10 and 20 years, and > 20 years). All histological examinations were performed without knowledge of clinical outcomes. In each case, pathological cell types and clinical parameters were recorded.

RESULTS

The patients with HD duration of > 10 years showed distinct pathological characteristics, including acquired cystic disease of kidney-associated RCCs. The disease-free survival (DFS) rates of these groups were statistically different from one another (P < 0.05). RCC with a sarcomatoid component was found in cases having HD durations of > 10 years. The DFS rate of the patients with a sarcomatoid component was 55.9% at 5 years and 37.3% at 10 years.

CONCLUSIONS

HD duration influenced pathological cell types and tumour stages of RCCs in HD patients. Patients receiving > 10 years of HD experienced RCCs with a sarcomatoid component, which resulted in poor outcomes. Hence, patients receiving long-term HD, and especially those with > 10 years of HD, should have frequent and careful medical examinations.

[Cystic renal neoplasms. New entities and molecular findings]

Renal neoplasms with dominant cysts represent a broad spectrum of known as well as novel renal tumor entities. Established renal tumors with dominant cysts include cystic nephroma, mixed epithelial and stromal tumor, synovial sarcoma and multilocular cystic renal cancer (WHO classification 2004). Novel tumor types have recently been reported, which are also characterized by marked cyst formation. Examples are tubulocystic renal cancer and renal cancer in end-stage renal disease. These tumors are very likely to be included in a future WHO classification due to their characteristic phenotype and molecular features. Cysts and clear cell renal cell carcinoma frequently coexist in the kidneys of patients with von Hippel-Lindau disease. Cysts are also a component of many sporadic clear cell renal cell carcinomas. Multilocular cystic renal cell carcinoma is composed almost exclusively of cysts and is regarded as a specific subtype of clear cell renal cancer. Recent molecular findings suggest that clear cell renal cancer may develop via a cyst-dependent mechanism in von Hippel-Lindau syndrome as well as via cyst-independent molecular pathways in sporadic clear cell renal cancer.

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.

Cystic renal tumors: new entities and novel concepts

Cystic renal neoplasms and renal epithelial stromal tumors are diagnostically challenging and represent some novel tumor entities. In this article, clinical and pathologic features of established and novel entities are discussed. Predominantly cystic renal tumors include cystic nephroma/mixed epithelial and stromal tumor, synovial sarcoma, and multilocular cystic renal cell carcinoma. These entities are own tumor entities of the 2004 WHO classification of renal tumors. Tubulocystic carcinoma and acquired cystic disease-associated renal cell carcinoma are neoplasms with an intrinsically cystic growth pattern. Both tumor types should be included in a future WHO classification as novel entities owing to their characteristic features. Cysts and clear cell renal cell carcinoma frequently coexist within the kidneys of patients with von Hippel-Lindau disease. Sporadic clear cell renal cell carcinomas often contain cysts, usually as a minor component. Some clear cell renal cell carcinomas have prominent cysts, and multilocular cystic renal cell carcinoma is composed almost exclusively of cysts. Recent molecular findings suggest that clear cell renal cancer may develop through cyst-dependent and cyst-independent molecular pathways.