Clear cell clusters in the kidney: a rare finding that should not be misdiagnosed as renal cell carcinoma.

Clear cytoplasm is a major characteristic feature of most malignant renal neoplasms. Benign clear cells in the renal parenchyma, usually histiocytes, can occasionally be found, but they are infrequently of an epithelial nature. We report histological, immunohistochemical, ultrastructural, and cytogenomic features of clear epithelial cell clusters incidentally found in four kidney specimens. Multiple microscopic clear cell clusters were present in the cortex, often in subcapsular location. They were composed of large epithelial cells with strikingly clear cytoplasm, without nuclear atypia, arranged in solid nests, and some tubules with narrow lumina. Immunohistochemically, they were positive for AE1AE3, PAX 8, EMA, kidney-specific cadherin, cytokeratin 7, E cadherin, and CD117, with focal immunoreactivity for CD10. Carbonic anhydrase IX, vimentin, and markers related to apoptosis and proliferation were negative. Ultrastructurally, the cytoplasms were enlarged and poor in organelles, showing ballooning degeneration. Array comparative genomic hybridization showed no chromosomal gains or losses. Clear cell clusters constitute a rare finding in the kidney and must be differentiated from benign lesions (ectopic adrenal tissue, osmotic tubulopathy, histiocytic clusters, renal adenomas) and renal cell carcinomas. Clear cell clusters appear to be generated from "endocrine-type" atrophic tubules whose cells are enlarged due to intracellular oedema. Immunohistochemistry shows a distal nephron phenotype with a limited expression of a proximal marker, CD10. Coexisting chronic renal disease or ischemic conditions seem to be related to the development of clear cell clusters. Pathological, ultrastructural, and cytogenomic features do not support a preneoplastic nature of this lesion, at least in the cases studied here.

Extracellular vesicle isolation from human renal cancer tissue.

Renal cell carcinoma is a lethal disease that is often discovered incidentally. New non-invasive biomarkers are needed to aid diagnosis and treatment. Extracellular vesicles (EVs), membranous vesicles secreted by all cells, are a promising potential source for cancer biomarkers, but new methods are required that are both sensitive and specific for cancer identification. We have developed an EV isolation protocol optimized for kidney tumor and normal kidney tissue that yields a high vesicle concentration, confirmed by nanoparticle tracking analysis (NanoSight) and by nanoscale flow cytometry (NanoFCM). Using Western blot, we confirmed presence of EV markers CD81, CD63, flotillin-1, and absence of cellular debris, calnexin. Transmission electron microscopy images demonstrate intact membranous EVs. This new method improves existing protocols with additional steps to reduce contaminants in the EV product. Characterization of our isolation product confirms successful isolation of EVs with minimal contamination. The particle yields of our protocol are consistent and high as assessed by both standard and novel methods. This optimized protocol will contribute to biomarker discovery and biological studies of EVs in renal cancer.

[Tubulocystic renal cell carcinoma. A rare entity in neoplastic renal pathology]. / Carcinoma tubuloquístico. Una entidad infrecuente en la patología tumoral renal.

Tubulocystic renal carcinoma is an uncommon neoplasm. We present a case of a patient presenting with multiple renal colic. A nodular cystic lesion was an incidental sonographic finding which increased in size during subsequent follow-ups. The patient underwent radical nephrectomy and tubular renal carcinoma was diagnosed histopathologically and immunohistochemically.

Renal-type clear cell carcinoma of prostate: A case report and review of literature.

We analyzed the clinicopathological features of renal-type clear cell carcinoma (RTCCC) in the prostate and its diagnosis according to the example in our hospital and review of the literature. Clinicopathological features of RTCCC in the prostate were observed in a patient from our hospital combining with a review of the literature. Microscopically, the tumor was composed of cells with abundant and translucent cytoplasm, arranged in the form of the vesicular nest or glandular structure. Therefore, it was necessary to distinguish between metastatic clear cell renal cell carcinoma and primary RTCCC in the prostate. Immunohistochemistry (IHC) of this case showed tumor cells were positive expression for cytokeratin (CKpan), low-molecular weight cytokeratin, epithelial membrane antigen, and prostate-specific antigen (PSA), P504S, prostate-specific membrane antigen and partial positive expression for vimentin and CD10. The tumor cells displayed negative expression of high molecular weight cytokeratin, cytokeratin 7 (CK7), CK34, PAX8, and renal cell carcinoma. The morphological and immunohistochemical features of this tumor were in correspondence with RTCCC of the prostate. This tumor is a rare variant of the prostate carcinomas. To the best of our knowledge, this type of extrarenal tumor has only been reported in six previous studies. Combination of histology, IHC, imaging, and serum PSA is needed to perform a suitable diagnosis.

Birt-Hogg-Dubé syndrome: awareness is important!

Birt-Hogg-Dubé (BHD) is a rare syndrome of inherited renal cell carcinomas, characterised by cutaneous lesions and pulmonary cysts and pneumothorax in a vast majority of the patients. Awareness of this syndrome is important in order to refer patients for genetic counselling and personalised follow-up as soon as possible. We describe a case of a 30-year-old female referred to our institution due to incidental discovery of solid bilateral renal masses. Renal biopsies were consistent with chromophobe tumour, and bilateral nephrectomy was performed. Gross examination revealed deformed kidneys with 28 brown and solid lesions, size variable between 0.1 and 6 cm, histologically corresponding to renal cell carcinomas, chromophobe type. Genetic test was required that showed a c.573delGAinsT frameshift mutation in heterozigosity at the folliculin gene, consistent with BHD diagnosis.

Leukocyte telomere length and renal cell carcinoma survival in two studies.

BACKGROUND: Leukocyte telomere length (LTL) is a potential biomarker of cancer prognosis; however, evidence for renal cell carcinoma (RCC) is inconsistent. METHODS: We investigated LTL and RCC-specific survival among 684 cases from the US kidney cancer study (USKC) and 241 cases from the prostate, lung, colorectal, and ovarian cancer screening trial (PLCO). Leukocyte telomere length was measured by quantitative polymerase chain reaction, and hazard ratios (HRs) and 95% confidence intervals (CIs) computed using multivariable Cox models. RESULTS: Short LTL was associated with poorer disease-specific survival in both USKC (lowest vs highest quartile: HR: 2.3, 95% CI: 1.2-4.4; P for trend=0.02) and PLCO (HR: 2.4, 95% CI: 1.0-5.4; P=0.04). Among USKC cases, the association was strongest for stage-I RCC (HR: 5.5, 95% CI: 1.6-19.0; P=0.006). CONCLUSIONS: Our findings suggest that shorter LTL is an independent marker of poor RCC prognosis, particularly for stage-I disease.

Xp11 Translocation Renal Cell Carcinomas (RCCs) With RBM10-TFE3 Gene Fusion Demonstrating Melanotic Features and Overlapping Morphology With t(6;11) RCC: Interest and Diagnostic Pitfall in Detecting a Paracentric Inversion of TFE3.

Xp11 translocation renal cell carcinomas (RCC) are characterized by several different translocations involving the TFE3 gene. Tumors with different specific gene fusions may have different clinicopathologic manifestations. Only 3 RBM10-TFE3 RCCs have been reported to date. Here, we added 4 cases of this rare type of tumors with clinicopathologic, immunohistochemical, molecular, and ultrastructural analyses. Most tumors had similar patterns with mixed architectures as follows: acinar, tubular and papillary patterns of epithelioid cells combined with sheets of small cells with "pseudorosette-like" architectures, mimicking the typical morphology of t(6;11) RCC. Cytoplasmic vacuolization, nuclear groove, and psammoma bodies were observed in most cases. Immunohistochemically, all 4 cases demonstrated moderate to strong immunoreactivity for TFE3, Cathepsin K, CD10, Ksp-cadherin, E-cadherin, P504S, RCC marker, PAX8 and vimentin, whereas negativity for TFEB, HMB45, and CK7. CKpan and Melan-A were at least focally expressed. The antibody to Ki-67 showed labeling of 3% to 8% (mean, 5%) of tumor cell nuclei. ;Of interest, several immunostainings demonstrated expression discrepancy in different histology patterns. RBM10-TFE3 fusion transcripts were identified in all cases by reverse transcription-polymerase chain reaction. By fluorescence in situ hybridization, all 4 cases showed unusual split signals with a distance <1 signal diameter (co-localized or subtle split signals) and usually had false-negative results. We also observed ultrastructures, including melanin pigment, nuclear groove, numerous glycogens, mitochondrion with areas of high electron density material, basement membrane material, and cell junctions with poor development. All 4 patients were alive with no evidence of recurrent disease. Our report adds to the known data regarding RBM10-TFE3 RCC.

Age-Related Renal Microvascular Changes: Evaluation by Three-Dimensional Digital Imaging of the Human Renal Microcirculation Using Virtual Microscopy.

The renal microvasculature is targeted during aging, sometimes producing chronic kidney disease (CKD). Overdiagnosis of CKD in older persons is concerning. To prevent it, a new concept of "healthy aging" is arising from a healthy renal donor study. We investigated the renal microcirculatory changes of three older persons and compared them with that of one patient with nephrosclerosis using a three-dimensional (3D) reconstruction technique that we previously developed. This method uses a virtual slide system and paraffin-embedded serial sections of surgical material that was double-immunostained by anti-CD34 and anti-α smooth muscle actin (SMA) antibodies for detecting endothelial cells and medial smooth muscle cells, respectively. In all cases, the 3D images proved that arteriosclerotic changes in large proximal interlobular arteries did not directly induce distal arterial change or glomerulosclerosis. The nephrosclerotic patient showed severe hyalinosis with luminal narrowing of small arteries directly inducing glomerulosclerosis. We also visualized an atubular glomerulus and intraglomerular dilatation of an afferent arteriole during healthy aging on the 3D image and showed that microcirculatory changes were responsible for them. Thus, we successfully visualized healthy aged kidneys on 3D images and confirmed the underlying pathology. This method has the ability to investigate renal microcirculatory damage during healthy aging.

Review of renal cell carcinoma with rhabdoid features with focus on clinical and pathobiological aspects.

Rhabdoid morphology in renal cell carcinoma (RCC) may, like sarcomatoid change, be perceived as a type of dedifferentiation, and is a poor prognostic factor. Histologically, rhabdoid neoplastic cells are round to polygonal cells with globular eosinophilic cytoplasmic inclusions and eccentric vesicular nuclei and enlarged nucleoli. All types of RCC, including clear cell, papillary, chromophobe, collecting duct carcinoma, renal medullary carcinoma, acquired cystic disease-associated RCC, ALK-positive renal cancer and unclassified RCC, may display a variably prominent rhabdoid phenotype. Immunohistochemically, the cytoplasm of rhabdoid cells shows positivity for vimentin and/or cytokeratin. Ultrastructurally, cytoplasmic whorls/aggregates of intermediate filaments correspond to light microscopically observed inclusions. Genetically, a previous report suggests that combined loss of BAP1 and PBRM1 may be associated with rhabdoid morphology. As with sarcomatoid change, pathologists should describe, estimate and state the proportion of tumor cells with a rhabdoid phenotype in the routine pathology report of RCC.

Primary clear cell renal carcinoma cells display minimal mitochondrial respiratory capacity resulting in pronounced sensitivity to glycolytic inhibition by 3-Bromopyruvate.

Changes of cellular metabolism are an integral property of the malignant potential of most cancer cells. Already in the 1930s, Otto Warburg observed that tumor cells preferably utilize glycolysis and lactate fermentation for energy production, rather than the mitochondrial oxidative phosphorylation dominating in normal cells, a phenomenon today known as the Warburg effect. Even though many tumor types display a high degree of aerobic glycolysis, they still retain the activity of other energy-producing metabolic pathways. One exception seems to be the clear cell variant of renal cell carcinoma, ccRCC, where the activity of most other pathways than that of glycolysis has been shown to be reduced. This makes ccRCC a promising candidate for the use of glycolytic inhibitors in treatment of the disease. However, few studies have so far addressed this issue. In this report, we show a strikingly reduced mitochondrial respiratory capacity of primary human ccRCC cells, resulting in enhanced sensitivity to glycolytic inhibition by 3-Bromopyruvate (3BrPA). This effect was largely absent in established ccRCC cell lines, a finding that highlights the importance of using biologically relevant models in the search for new candidate cancer therapies. 3BrPA markedly reduced ATP production in primary ccRCC cells, followed by cell death. Our data suggest that glycolytic inhibitors such as 3BrPA, that has been shown to be well tolerated in vivo, should be further analyzed for the possible development of selective treatment strategies for patients with ccRCC.

[Renal urothelial carcinoma mainly composed of signet-ring cells].

Autopsy study of an 80-year-old man has identified his renal tumor metastasizing to the heart, lung, and liver as urothelial car- cinoma; at the same time some cells in the main tumor and all cells in the metastases had a signet-ring phenotype, but neither mucicarcimine nor alcian blue stained the cell cytoplasm. The paper provides the histological and immunohistochemical pattern of the tumor and emphasizes its exclusive rarity. Attention is drawn to the possibility of signet-ring cell transformation in the cells of different tumors, including nonepithelial ones.

The value of contrast-enhanced ultrasound (CEUS) in detecting minute renal cell carcinoma.

UNLABELLED: To investigate the value of contrast-enhanced ultrasound (CEUS) in the detection of minute renal cell carcinoma (MRCC) compared to conventional ultrasound (US) and contrast-enhanced computed tomography (CECT). METHODS: Thirty-eight consecutive patients with 38 histopathologically proven MRCCs (≦15 mm) were enrolled in our study. CEUS and CECT were available in 38 and 24 patients, respectively. The features of CEUS were evaluated and compared to conventional ultrasound (US) and CECT. RESULTS: Ten (26.3%) tumors could not be detected by conventional US, while all tumors were detected by CEUS. The features of tumor border, blood flow, and echogenicity had significant difference between conventional US and CEUS (p=0.000, p=0.003, and p=0.012, respectively). The score of visibility of tumors by CEUS was significant higher than that of conventional US. The sensitivity, specificity, and accuracy of conventional US and CEUS in evaluating tumor necrosis were 42.9%, 50%, and 47.4% vs. 85.7%, 95.8%, and 92.1%, respectively. The enhancement features of MRCC including tumor vascularization, homogeneity, and border had no significant difference between CEUS and CECT (all p>0.05). On CEUS, synchronous-in (89.5%), hypervascular (84.2%), and fast-out (71.1%) were the most commonly observed enhancement characteristics for MRCC. CONCLUSION: CEUS performs better in detecting MRCC than conventional US, and it has the same capabilities in reflecting the enhanced features of MRCC as CECT.

Renal cell carcinoma metastatic to a pituitary FSH/LH adenoma: case report and review of the literature.

Abstract Metastases to the pituitary occur more frequently in patients with widespread cancer and mainly involve the posterior lobe. A few cases of metastatic carcinoma to a pituitary adenoma have been described so far. Here, the authors present an additional case of a clear cell renal cell carcinoma (CCRCC) metastatic to a FSH/LH/α-subunit pituitary adenoma and systematically review the literature. Immunohistochemistry and electron microscopy were performed to characterize both neoplastic components at the morphological level. Moreover, it was hypothesized that expression of VEGF and of the corresponding receptor VEGFR1 could be implicated in the development of the carcinomatous metastasis within the adenoma.

[Clinicopathologic features of clear cell papillary renal cell carcinoma].

OBJECTIVE: To study the clinicopathological features, differential diagnosis and prognosis of clear cell papillary renal cell carcinoma (CCPRCC). METHODS: The histological, immunohistochemical, and molecular features were studied in 11 cases and follow-up data were also analyzed. RESULTS: There were a total of 3 females and 8 males. The age of patients were ranged from 33 to 72 years(mean age 52.5 years). The diameters of tumors varied from 1cm to 4 cm. Histologically, papillary and cystic architecture were present at least focally in all tumors. The papillae were covered by small to medium-sized cuboidal cells with abundant clear cytoplasm and often showed extensive secondary branching, which were often folded and densely packed, resulting in a solid appearance. The nuclei were round and uniform in shape; nucleoli were not prominent (Fuhrman grade 1 or 2). Neither mitotic figures nor necrosis was present. All 11 cases exhibited moderate to strong positivity for CK7, CA9, vimentin, and HIF-1α, coupled with negative reactions for CD10, P504S, and TFE3. Ksp-cadherin was positively expressed in 8 cases.VHL gene mutations were not found in all 11 cases. Losses of chromosomes 3 (monoploid chromosome 3) was detected in 3 cases. CONCLUSIONS: CCPRCC is uncommon and seemed to be an indolent tumor. The differential diagnosis should be included tumors, which harbor clear cell and papillary structure including clear cell renal cell carcinoma, papillary renal cell carcinoma, Xp11 translocation renal cell carcinoma, and CCPRCC. Immunohistochemical and molecular analysis may be help for its diagnosis.

Clear cell papillary renal cell carcinoma: a clinicopathological study emphasizing ultrastructural features and cytogenetic heterogeneity.

Clear cell papillary renal cell carcinoma (CCPRCC) is a recently recognized renal neoplasm, which was initially described in end-stage renal disease (ESRD), but some cases have been reported in otherwise normal kidneys. We report a series of 11 CCPRCC (age range, 33-72 years; male-to-female ratio, 8:3). Follow-up was available for 8 patients. No patients developed local recurrence, distant or lymph-node metastasis, or cancer death. Histologically, all tumors exhibit morphologic features typical of CCPRCC including a mixture of cystic and papillary components, covered by small to medium-sized cuboidal cells with abundant clear cytoplasm. All 11 cases exhibited moderate to strong positivity for CK7, CA9, Vim, and HIF-1α, coupled with negative reactions for CD10, P504S, and RCC. We did not find any VHL gene mutations in all 11 cases. Losses of chromosomes 3 (monoploid chromosome 3) was detected in 3 cases. Ultrastructurally, the tumor cells composed of numerous glycogens with scanty cell organelles, reminiscent of clear cell renal cell carcinoma (CCRCC). In conclusion, the coexpression of CA9 and HIF-1α in the absence of VHL gene abnormalities in CCPRCC suggests activation of the HIF pathway by mechanisms independent of VHL gene mutation. Losses of chromosomes 3 (monosomies chromosome 3) was detected in 3 cases suggesting that at least some of these lesions have demonstrated abnormalities of chromosomes 3. Ultrastructurally, CCPRCC composed of numerous glycogens with scanty cell organelles, reminiscent of CCRCC suggesting the close pathogenesis relationship of CCPRCC with CCRCC.

A prospective study of leukocyte telomere length and risk of renal cell carcinoma.

BACKGROUND: It has been hypothesized that genomic instability related to telomere dysfunction may contribute to carcinogenesis. There is some evidence from case-control studies suggesting that short leukocyte telomere length may be associated with an increased risk of renal cell carcinoma (RCC); however, this association has not been investigated prospectively. METHODS: We conducted a nested case-control study (209 cases, 410 controls) of RCC risk in relation to prediagnostic leukocyte telomere length in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. ORs and 95% confidence intervals (CI) were estimated using conditional logistic regression. RESULTS: Leukocyte telomere length was not significantly associated with future risk of RCC (highest quartile vs. lowest: OR, 0.8; 95% CI, 0.5-1.5; Ptrend = 0.6). Analyses stratified by sex, age, and time from blood collection to RCC diagnosis were similarly null. CONCLUSIONS: The results of this study, to our knowledge the first prospective investigation of its kind, do not support an association between prediagnostic leukocyte telomere length and risk of RCC. IMPACT: In contrast to some earlier reports, our findings add to the evidence that leukocyte telomere length is not a biomarker of risk related to the etiology of RCC.

Evaluation of morphologically unclassified renal cell carcinoma with electron microscopy and novel renal markers: implications for tumor reclassification.

Despite progress in the classification of renal cell carcinomas (RCC), a subset of these carcinomas remains unclassified (RCC-U). Patients with RCC-U usually present at a late stage and have a poor prognosis. Several studies have attempted to extract new classifications of newly recognized renal carcinomas from the group of RCC-U. However, to date, no studies in the literature have attempted to characterize the RCC-U with unrecognizable cell types beyond the morphologic evaluation on H&E-stained sections. The purpose of this study was to evaluate this group of RCC-U using electron microscopy and novel renal markers. Ten cases of such RCC-U were identified for this study. At the ultrastructural level, they did not show typical morphology that resembled any of the well-studied, recognizable subtypes of RCC. However, they did reveal features of renal tubular epithelial differentiation. The histologic, ultrastructural, and immunophenotypic features indicated that these tumors are poorly differentiated renal epithelial tumors, possibly derived from the proximal nephron, with an immunohistochemical profile similar to high-grade clear cell RCC. It is, therefore, proposed that this group of renal carcinomas be renamed "poorly differentiated renal cell carcinoma, not otherwise specified." The current study showed that PAX-8 and carbonic anhydrase IX are reliable markers for this novel group of renal carcinoma, and that electron microscopy is an important adjunct in the evaluation of new and unusual renal entities.

Interobserver reproducibility of a grading system for chromophobe renal cell carcinoma.

OBJECTIVES: To evaluate interobserver reproducibility of a grading system proposed by Paner et al. for chromophobe renal cell carcinoma. MATERIAL AND METHODS: After selecting 23 cases of chromophobe renal cell carcinoma from the Xeral-Cíes Hospital, Meixoeiro Hospital and POVISA Hospital from the last 15 years, an informative meeting on the Paner et al. grading system criteria was held. After, the participating pathologists applied the system to each case, evaluating one slide selected. Kappa index for interobserver reproducibility was calculated, and it was classified according to the Landis and Koch scale. RESULTS: The grading distribution was similar for most of the 6 participating observers, with grade 1 predominance. The remaining 2 observers considered a relatively higher proportion of grade 2. Kappa index values ranged from 0.136 to 0.674, with a discrete-moderate reproducibility index predominance (0.21-0.60). Highest Kappa value (0.674) was obtained between the most novel and the most expert interobservers. The lowest Kappa value was obtained among the most veteran pathologists (0.136). CONCLUSIONS: Interobserver reproducibility for chromophobe renal cell carcinoma is discrete-moderate in our institutions when the novel grade proposed by Paner et al. is used. Labeling of grades 1 and 2 is not homogeneous among 6 participating observers. While awaiting a grading consensus on a new classification by the scientific societies, we consider that the routine use of a grading system for chromophobe renal cell carcinoma should not be used.