Liver-related Mortality is Increased in Lean Subjects with Non- alcoholic Fatty Liver Disease Compared to Overweight and Obese Subjects.

BACKGROUND AND AIMS: Although non-alcoholic fatty liver disease (NAFLD) is linked to obesity, a proportion of lean subjects also have NAFLD with potentially distinct clinical features. We studied the outcome of lean NAFLD subjects. METHODS: 299 consecutive patients (215 male, 84 female, 49.5 ± 13.5years) with biopsy-proven NAFLD and a follow-up of 8.4 years (±4.1; range: 0.9-18.0) were stratified by body mass index (BMI) at the time of liver biopsy: lean (BMI ≤25.0 kg/m, n=38), overweight (BMI 25.0-29.9 kg/m2, n=165), obese (BMI ≥30.0 kg/m2, n=93). A control group of 1,013 subjects (547 male, 52.4 ± 5.8) was used for comparison. The time to the event was recorded. Multivariable Cox regression analyses were performed to assess associations with 10-year-mortality. Hazard ratios (HR) and adjusted hazard ratios (aHR) with 95% confidence intervals (CI) were calculated. RESULTS: Age and gender were similar, while components of the metabolic syndrome were less frequent in lean subjects. The proportion of subjects with significant fibrosis and the number of subjects with cirrhosis was increased in lean subjects while the proportion of non-alcoholic steatohepatitis was not different. Mortality in the NAFLD groups was significantly higher than in the control group. Multivariable analysis adjusting for age, gender, and glucose confirmed lower mortality in overweight (aHR 0.21; 95% CI 0.07-0.62, p=0.005) and in obese (aHR 0.22; 95% CI 0.06-0.76, p=0.02) compared to lean subjects. Further adjustment for fibrosis weakened the difference between lean and obese (p=0.12) while the difference to overweight subjects remained intact (p=0.01). CONCLUSION: Lean subjects with NAFLD have a high risk of liver-related death. Our data support that lean NAFLD subjects deserve particular attention with regard to clinical follow-up.

Mesenchymal iron deposition is associated with adverse long-term outcome in non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Approximately one-third of patients with non-alcoholic fatty liver disease (NAFLD) show signs of mild-to-moderate iron overload. The impact of histological iron deposition on the clinical course of patients with NAFLD has not been established. METHODS & RESULTS: For this retrospective study, 299 consecutive patients with biopsy-proven NAFLD and a mean follow-up of 8.4 (±4.1; range: 0.3-18.0) years were allocated to one of four groups according to presence of hepatic iron in the reticuloendothelial system (RES) and/or hepatocytes (HC): 156 subjects (52%) showed no stainable iron (NONE), 58 (19%) exclusively reticuloendothelial (xRES), 19 (6%) exclusively hepatocellular (xHC) and 66 (22%) showed a mixed (HC/RES) pattern of iron deposition. A long-term analysis for overall survival, hepatic, cardiovascular or extrahepatic-malignant events was conducted. Based on multivariate Cox proportional hazards models any reticuloendothelial iron was associated with fatal and non-fatal hepatic events. Specifically, xRES showed a cause-specific hazard ratio (csHR) of 2.4 (95%-CI, 1.0-5.8; P = .048) for hepatic as well as cardiovascular fatal and non-fatal events combined (csHR 3.2; 95%-CI, 1.2-8.2; P = .015). Furthermore, the mixed HC/RES iron pattern showed a higher rate of combined hepatic fatal and non-fatal events (csHR 3.6; 95%-CI, 1.4-9.5; P = .010), while xHC iron deposition was not associated with any defined events. CONCLUSIONS: The presence of reticuloendothelial-accentuated hepatic iron distribution patterns is associated with detrimental long-term outcomes reflected in a higher rate of both liver-related and cardiovascular fatal and non-fatal events.

Lean Patients with Non-Alcoholic Fatty Liver Disease Have a Severe Histological Phenotype Similar to Obese Patients.

A small proportion of lean patients develop non-alcoholic fatty liver disease (NAFLD). We aimed to report the histological picture of lean NAFLD in comparison to overweight and obese NAFLD patients. Biopsy and clinical data from 466 patients diagnosed with NAFLD were stratified to groups according to body mass index (BMI): lean (BMI ≤ 25.0 kg/m², n confirmed to be appropriate = 74), overweight (BMI > 25.0 ≤ 30.0 kg/m², n = 242) and obese (BMI > 30.0 kg/m², n = 150). Lean NAFLD patients had a higher rate of lobular inflammation compared to overweight patients (12/74; 16.2% vs. 19/242; 7.9%; p = 0.011) but were similar to obese patients (25/150; 16.7%). Ballooning was observed in fewer overweight patients (38/242; 15.7%) compared to lean (19/74; 25.7%; p = 0.014) and obese patients (38/150; 25.3%; p = 0.006). Overweight patients had a lower rate of portal and periportal fibrosis (32/242; 13.2%) than lean (19/74; 25.7%; p = 0.019) and obese patients (37/150; 24.7%; p = 0.016). The rate of cirrhosis was higher in lean patients (6/74; 8.1%) compared to overweight (4/242; 1.7%; p = 0.010) and obese patients (3/150; 2.0% p = 0.027). In total, 60/466; 12.9% patients were diagnosed with non-alcoholic steatohepatitis (NASH). The rate of NASH was higher in lean (14/74; 18.9% p = 0.01) and obese (26/150; 17.3%; p = 0.007) compared to overweight patients (20/242; 8.3%)). Among lean patients, fasting glucose, INR and use of thyroid hormone replacement therapy were independent predictors of NASH in a multivariate model. Lean NAFLD patients were characterized by a severe histological picture similar to obese patients but are more progressed compared to overweight patients. Fasting glucose, international normalized ratio (INR) and the use of thyroid hormone replacement may serve as indicators for NASH in lean patients.

Natural course of subjects with elevated liver tests and normal liver histology.

BACKGROUND & AIMS: Liver biopsy (LB) is performed if non-invasive work-up of liver disease is inconclusive. The examination of liver tissue occasionally reveals normal histology. Long-term follow-up of such patients has not been performed. METHODS: We identified a total 70 subjects from our LB database with elevated liver tests and normal liver histology after a mean of 90.5 ± 52.3 (range 15-216) months and conducted reassessment of medical history, physical examination, laboratory testing, ultrasound, transient elastography and LB if indicated. RESULTS: At follow-up examination, 15 (7 females (f)/8 males (m); 21.4%) subjects had normal liver tests and no further evidence of liver disease. A subset of 37 (29 f/8 m; 52.9%) subjects had persistently elevated liver tests without evidence indicating progressive liver disease but the cause thereof remained unexplained also at the follow-up visit. Three (0 f/3 m; 4.3%) subjects had consumed excessive alcohol with indicators of alcoholic liver disease. Eleven subjects (4 f/7 m; 15.7%) had developed steatosis on ultrasound examination along with weight gain and/or biochemical features of the metabolic syndrome. In addition, three (2 f/1 m) patients developed autoimmune hepatitis, one female presented with primary biliary cirrhosis. One male was diagnosed with cholangiocellular carcinoma 3 months after the initial evaluation. CONCLUSION: The clinical course of most patients was benign, but in approximately 20% of the subjects a liver disease developed. Particular attention should be given to autoimmune liver diseases in subjects with positive autoantibodies. In addition, lifestyle factors such as weight gain and alcohol consumption were associated with the manifestation of liver diseases.

pS6 Expression in normal renal parenchyma, primary renal cell carcinomas and their metastases.

In cancer therapy novel concepts focus on phosphoinositide-3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) inhibitors. In this context, phosphorylated S6 protein of the 40S ribosomal subunit (pS6) overexpression was previously shown to be associated with sensitivity to inhibitors of mTOR. The present study therefore evaluated pS6 expression in normal renal parenchyma (NRP), primary renal cell carcinomas (PRCC) and their metastases. pS6 and pmTOR expression was immunohistochemically analyzed in a tissue microarray (TMA) from localized primary renal cell carcinoma (lPRCC) (n = 35), metastasized primary renal cell carcinoma (mPRCC) (n = 45), their metastases (n = 45), and NRP (n = 45). pS6 expression was stronger in mPRCCs and metastases than in NRP and lPRCCs (p < 0.05). In mPRCCs high-grade and high-stage tumors showed higher pS6 levels. pS6 overexpression was more frequently found in metastases (40/45; 88.9%) than in mPRCC (24/45; 53.3%) (p < 0.05). Overexpression of pS6 in metastases without concomitant overexpression in their primary tumors was found in 16/45 (35.56%) cases. Patients with pS6 overexpression in mPRCCs but also in metastases showed a tendency to shorter overall survival. pS6 score and pmTOR score correlated positively in NRP and in tumorous tissue (mPRCC and metastases). In conclusion, the present study showed stronger pS6 expression and more frequent overexpression in metastases than in corresponding PRCCs. In approximately one-third of the cases pS6 overexpression was found exclusively in metastases, which is interesting with regard to the association between high pS6 expression and sensitivity to mTOR inhibitor therapy.

PTEN, pAKT, and pmTOR expression and subcellular distribution in primary renal cell carcinomas and their metastases.

The present study evaluated pAKT, pmTOR, and PTEN expression in a tissue microarray of primary renal cell carcinomas (PRCCs), their metastases, and normal renal parenchyma (NRP) (N = 45) by means of immunohistochemistry. Metastases in most subcellular compartments showed comparable and stronger expression for pAKT, pmTOR, and PTEN than PRCC and NRP, which was even more pronounced in patients with high-risk Memorial Sloan-Kettering Cancer Center (MSKCC) score. Furthermore, most subcellular compartments showed no differences between lymphogenous, haematogenous, synchronous, and metachronous metastases, which is interesting with regard to sensitivity to mTOR inhibitor therapy in metastasized RCCs with alterations in the PI3K/AKT pathway.

Surgical vein occlusion--comparison of four different methods in a rat model.

BACKGROUND: Among many aspects, wound healing depends on early restoration of venous blood flow across wound margins. The type of surgical occlusion of vein stumps during operations was assumed to have an influence on the early postoperative reunion of vein stumps and thereby on wound healing. Currently, there are different methods of vein stump occlusion available: ligation (e.g., Vicryl), closure using metal clips (e.g., LigaClip), coagulation using manually controlled bipolar forceps, and the use of a computer-controlled bipolar system (e.g., BiClamp). The aim of this study was to surgically and histologically compare the healing process, including new vessel formation after vein occlusion using one of the methods listed. METHODS: In a rat model (n = 50), both jugular and femoral veins were prepared, occluded twice with one of the methods mentioned above (i.e., 400 occlusions), and finally cut in-between. Groups of 10 animals were reoperated and evaluated surgically and histologically after 5 days, 10 days, 15 days, 30 days, and 90 days. RESULTS: Occlusion methods using Vicryl, LigaClip, or bipolar forceps allow highly reliable vessel occlusion. Surgical evaluation showed higher occurrence of vessels in between the vein stumps after usage of Vicryl and LigaClip when compared with electrothermic occlusion methods (p = 0.017). Histologic examination showed different courses of the inflammatory reaction and varying capillary counts. Bipolar occlusion methods do cause less vessel occurrence, less inflammatory reaction, and less histologic capillary formation. CONCLUSION: If a reconnection of the venous flow is desirable, the use of Vicryl and LigaClip might be superior to using electrothermic occlusion methods. In contrast, electrothermic methods cause less new vessel formation as well as less inflammatory reaction.

p-AKT overexpression in primary renal cell carcinomas and their metastases.

In cancer therapy novel concepts focus on phosphoinositide 3-kinase (PI3K)/activated protein kinase B (p-AKT)/mammalian target of rapamycin (mTOR) inhibitors. In this context, p-AKT overexpression was previously shown to be associated with sensitivity to inhibitors of mTOR. The present study evaluated p-AKT expression in a tissue microarray of primary renal cell carcinomas (PRCCs) (n = 45), their metastases (primary onset n = 45, secondary onset n = 5), and normal renal parenchyma (n = 45) by means of immunohistochemistry. Total p-AKT overexpression was found in 24/45 (53.3%) PRCCs, in 32/45 (71.1%) primary and in 3/5 (60%) secondary onset metastases. Membranous p-AKT overexpression was seen more frequently in PRCCs, namely 11/45 (24.4%), than in primary onset metastases 1/45 (2.2%). Overexpression of total p-AKT solely in metastases without overexpression in PRCC was exclusively demonstrated in primary onset metastases, namely in 28.9%. Patients with total p-AKT overexpression in primary carcinomas showed a trend to longer, and those with total p-AKT overexpression in metastases a tendency to shorter survival. In conclusion, the present study shows total p-AKT overexpression to be more frequent in metastases than in PRCCs. Total p-AKT overexpression in metastases without concomitant overexpression in their primary tumors was found in approximately one-third of primary onset metastases, which is interesting with regard to the association between high p-AKT expression and sensitivity to mTOR inhibitor therapy.

A role for low hepatic copper concentrations in nonalcoholic Fatty liver disease.

OBJECTIVES: Copper has a role in antioxidant defense, lipid peroxidation, and mitochondrial function, and copper deficiency has been linked to atherogenic dyslipidemia. We aimed to investigate the potential role of copper availability in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). METHODS: Patients with NAFLD (n=124) were compared to patients with chronic hepatitis C (n=50), hemochromatosis (n=35), alcoholic liver disease (n=13), autoimmune hepatitis (n=11), and control subjects (n=27). We determined liver and serum copper concentrations with correlation to clinical, histological, and biochemical parameters in humans. The effect of dietary copper restriction on liver histology and intermediary metabolism in rats was investigated. RESULTS: Hepatic copper concentrations in patients with NAFLD were lower than in control subjects (17.9+/-8.4 vs. 31.4+/-8.2 microg/g; P<0.001) and in patients with other liver diseases (P<0.05 for all liver diseases). In patients with NAFLD, lower liver copper was correlated with more pronounced hepatic steatosis (R=-0.248; P=0.010), fasting glucose (R=-0.245; P=0.008), and components of the metabolic syndrome (MetS; R=0.363; P<0.001). Patients with nonalcoholic steatohepatitis (NASH; n=31) had lower hepatic copper concentrations than those with simple steatosis (n=93; P=0.038). Restriction of dietary copper in rats induced hepatic steatosis and insulin resistance (IR). CONCLUSIONS: Reduced hepatic copper concentrations are found in human NAFLD and are associated with more pronounced hepatic steatosis, NASH, and components of the MetS. The development of hepatic steatosis and IR in response to dietary copper restriction in rats suggests that copper availability may be involved in the development of NAFLD.

Chromosomal imbalances, 11q21 rearrangement and MECT1-MAML2 fusion transcript in mucoepidermoid carcinomas of the salivary gland.

The aim of this study was to determine genetic alterations in mucoepidermoid carcinomas of the salivary gland in association with clinical and histopathological parameters. Nineteen formalin-fixed, paraffin-embedded tumors were analysed by using comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH) on interphase nuclei and reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of MECT1-MAML2 fusion transcript. The CGH analysis showed an overrepresentation of chromosome X and losses of entire chromosomes or regions on chromosome 1, 2, and 15 as the most frequent copy number changes. In 37% of the analysed tumors a MAML2-rearrangement by interphase FISH was detected, whereas 58% of the samples showed expression of MECT1-MAML2 fusion transcript. We conclude that the presence of MAML2-rearrangement as well as of MECT1-MAML2 fusion transcript may reflect a more favourable prognosis and may be a useful marker for clinical prediction of the biological behavior of these tumors as previously reported.

Increased activated Akt expression in renal cell carcinomas and prognosis.

Renal carcinogenesis is promoted by overexpression of the activated serine/ threonine kinase Akt (p-Akt) and supposedly a concomitant reduction in phosphatase and tensin homologue deleted on chromosome 10 tumour suppressor gene (PTEN), which normally inhibits the activation of Akt. Because promising anti-cancer therapies increasingly focus on pathways involving p-Akt and PTEN, the present study evaluated the expression of p-Akt in renal cell carcinomas and compared it with prognosis. P-Akt and PTEN expression were analysed in a tissue microarray (TMA) from renal cell carcinoma (n = 386) and adjacent uninvolved renal tissue (n = 32) specimens. Increased p-Akt was found more often in the nucleus than in the cytoplasm, and PTEN was concomitantly reduced in about 50% of cases. Neither tumour grade nor stage influenced p-Akt expression, whereas the clear cell and papillary subtypes showed increased p-Akt more often than did the chromophobe or sarcomatoid types. Increased cytoplasmic and nuclear p-Akt levels were independent prognostic factors for diminishing patient survival. The present study found significantly increased nuclear but also cytoplasmic p-Akt expression in renal cell carcinoma subtypes. Increased nuclear and cytoplasmic p-Akt was an independent prognostic factor for diminishing patient survival. The considerable number of high-grade and high-stage RCC showing increased p-Akt and reduced PTEN would justify further evaluation of therapeutic concepts based on inhibitors of the PI3K/p-Akt/mTOR pathway.

Association between atherosclerosis and urothelial tumors of the renal pelvis.

OBJECTIVES: An association between the prevalence of general and local atherosclerosis and various types of cancer has previously been reported. The present study therefore aimed to morphometrically compare atherosclerotic changes in kidneys with urothelial carcinomas of the renal pelvis and tumor-negative renal tissue. MATERIALS AND METHODS: The intima-to-media ratio (IMR), which is the most sensitive marker for the degree of atherosclerosis, was evaluated in arteries (n = 492) of non-invasive papillary urothelial carcinoma (n = 128), invasive urothelial carcinoma (n = 168) and tumor-negative renal specimens (n = 196). RESULTS: IMR was significantly higher and more often exceeded 1 in invasive and non-invasive urothelial carcinomas than in tumor-negative specimens. Furthermore, in invasive urothelial carcinomas IMR was significantly higher in immediately peritumorous arteries than in more distant arteries. Moreover, IMR correlated weakly with age and renal parenchymal inflammation but not with peritumorous inflammation, coronary heart disease (CHD) or gender. CONCLUSION: Local atherosclerosis was more pronounced in tumor-positive than in tumor-negative renal specimens. IMR > 1 was significantly associated with urothelial tumors and the overall odds of having a urothelial tumor were significantly greater for patients with an IMR > 1 than for patients with an IMR < or = 1, supporting the view that patients with local atherosclerotic lesions are at elevated risk for urothelial carcinoma of the renal pelvis.

Pathways underlying iron accumulation in human nonalcoholic fatty liver disease.

BACKGROUND: Mild iron overload is frequently observed in nonalcoholic fatty liver disease (NAFLD). OBJECTIVE: We aimed to study putative pathways underlying iron accumulation in NAFLD. DESIGN: Hepatic and duodenal expression of critical iron molecules in NAFLD patients with (n = 32) and without (n = 29) iron overload, hereditary hemochromatosis (n = 10), and controls (n = 20) were investigated. Phlebotomy treatment was performed in 14 NAFLD patients. RESULTS: The hepatic expressions of the iron-export protein ferroportin-1 (FP-1) and of the iron-sensing molecule hemojuvelin (HJV) were significantly lower in NAFLD patients. The mRNA expression of the iron-regulatory peptide hepcidin was increased in NAFLD patients with iron overload, which was paralleled by low duodenal FP-1 expression. Hepatic mRNA and serum protein concentrations of tumor necrosis factor-alpha (TNF-alpha) were increased in NAFLD patients and were inversely correlated with both liver FP-1 and HJV mRNA and positively associated with body mass index and hepatic hepcidin mRNA. Accordingly, TNF-alpha inhibited the FP-1 and HJV mRNA formation in HepG2 cells. Phlebotomy treatment of NALFD patients reduced serum ferritin, transferrin saturation, and TNF-alpha concentrations and improved liver function tests. CONCLUSIONS: Iron accumulation in NAFLD may result from an impaired iron export due to down-regulation of FP1 and ineffective hepatic iron sensing, as indicated by low HJV expression. TNF-alpha appears to play a role in exerting these regulatory changes. Increased hepcidin formation in iron-overloaded NAFLD patients, however, results in decreased duodenal FP-1 expression, whereas a reduction in liver FP-1 may perpetuate hepatic iron retention. Phlebotomy offers a safe and efficient therapy for these metabolic disturbances.

Copper availability contributes to iron perturbations in human nonalcoholic fatty liver disease.

BACKGROUND & AIMS: Iron perturbations are frequently observed in nonalcoholic fatty liver disease (NAFLD). We aimed to investigate a potential association of copper status with disturbances of iron homeostasis in NAFLD. METHODS: We retrospectively studied 140 NAFLD patients and 25 control subjects. Biochemical and hepatic iron and copper parameters were analyzed. Hepatic expression of iron regulatory molecules was investigated in liver biopsy specimens by reverse-transcription polymerase chain reaction and Western blot analysis. RESULTS: NAFLD patients had lower hepatic copper concentrations than control subjects (21.9 +/- 9.8 vs 29.6 +/- 5.1 microg/g; P = .002). NAFLD patients with low serum and liver copper concentrations presented with higher serum ferritin levels (606.7 +/- 265.8 vs 224.2 +/- 176.0 mg/L; P < .001), increased prevalence of siderosis in liver biopsy specimens (36/46 vs 10/47 patients; P < .001), and with elevated hepatic iron concentrations (1184.4 +/- 842.7 vs 319.9 +/- 451.3 microg/g; P = .020). Lower serum concentrations of the copper-dependent ferroxidase ceruloplasmin (21.7 +/- 4.1 vs 30.4 +/- 6.4 mg/dL; P < .001) and decreased liver ferroportin (FP-1; P = .009) messenger RNA expression were found in these patients compared with NAFLD patients with high liver or serum copper concentrations. Accordingly, in rats, a reduced dietary copper intake was paralleled by a decreased hepatic FP-1 protein expression. CONCLUSIONS: A significant proportion of NAFLD patients should be considered copper deficient. Our results indicate that copper status is linked to iron homeostasis in NAFLD, suggesting that low copper bioavailability causes increased hepatic iron stores via decreased FP-1 expression and ceruloplasmin ferroxidase activity thus blocking liver iron export in copper-deficient subjects.

PTEN expression in renal cell carcinoma and oncocytoma and prognosis.

AIMS: Deletion or inactivation of the tumour suppressor gene PTEN (phosphatase and tensin homologue deleted from chromosome 10) contributes to tumorigenesis in a variety of human carcinomas. The present study evaluated PTEN expression in renal cell carcinomas and oncocytomas. METHODS: A tissue microarray from 493 specimens including renal cell carcinomas (n = 440), oncocytomas (n = 21) and tumour-negative renal tissue (n = 32) from patients (n = 461) was incubated with an anti-PTEN antibody for subsequent analysis of PTEN expression. Furthermore, the effect of PTEN expression on the survival of renal carcinoma patients was evaluated. RESULTS: Renal cell carcinomas, and even more pronouncedly oncocytomas, expressed PTEN predominantly in the cytoplasm. In contrast to oncocytomas, PTEN expression was typically decreased in renal cell carcinoma subtypes. PTEN expression in sarcomatoid renal cell carcinomas was comparable to that in non-sarcomatoid subtypes. The PTEN expression pattern had no significant influence on prognosis. CONCLUSIONS: Renal tumours (renal cell carcinomas and oncocytomas) express PTEN protein predominantly in the cytoplasm. A reduction in PTEN expression appears to be an early step in renal cell carcinogenesis. However, the PTEN expression pattern of renal cell carcinomas apparently is not prognostic for patient survival.

Tissue microarrays from renal cell tumors: exclusion criteria and rate of exclusion.

OBJECTIVES: Exclusion of tissue microarray (TMA) cores can cause the total loss of a tumor case, and this can have a potentially negative effect on the results of TMA-based studies. The main aim of this study was to evaluate the loss of informative cores having cut a given number of slices from a TMA block. A further objective was to investigate the effect in various subtypes of renal cell tumors and the detailed reasons for the loss of informative cores. MATERIAL AND METHODS: A TMA was constructed from renal tumor specimens (n=461). The cause and rate of exclusion were evaluated in the first slice (FS) and last slice (LS) (i.e. the 40th) cut from the TMA blocks. Furthermore, the overall case loss under the assumptions that only one, two or three cores per case were punched was extrapolated. RESULTS: Sarcomatoid and papillary renal cell carcinomas showed the highest overall exclusion rate. Irrespective of the type of tumor, however, the case loss was approximately tripled from FS to LS. Furthermore, extrapolation showed that a reduction in the number of cores punched per case, for example by one, would further double the number of cases lost. Reasons for exclusion were mainly as follows: core loss; <25% tumorous tissue per core; core folding; and core with necrotic area. CONCLUSION: This study shows that punching at least three to four cores per case is advisable when constructing TMAs from oncocytoma and renal cell carcinoma specimens, and that the type of tumor has an effect on the cause and rate of core exclusion.