[Corneal epithelial diseases related to limbal stem cell deficiency]. / Pathologies épithéliales cornéennes et insuffisance en cellules souches limbiques.

Treatment of corneal epithelial diseases induced by limbal stem cell deficiency is an important challenge in ocular surface reconstruction. Since the 1990s, corneal stem cells have been localized in the limbus. This new concept completely changed the way we consider ocular surface reconstruction, with new diseases now found to be isolated in the ocular surface. Limbus insufficiency syndromes are specific depending on their origin (congenital or acquired), their expression (unilateral or bilateral, partial or total), their progression (acute or chronic), and the mechanism involved (burn, infection, chronic inflammation, etc.). Some of these diseases are local diseases and others are systemic diseases. Clinically, limbus insufficiency is a switch of the normal corneal epithelial phenotype (expression of a specific keratin, avascularity, and transparency of the corneal matrix) in an opaque and fibrovascularized cornea. In terms of cellular biology, a phenotype is a terminal expression of a cell differentiation process. This process is the outcome of the interaction between the genome of a cell or a group of cells with their microenvironment. In limbus insufficiency, epithelial cells and corneal matrix are destroyed, and it is the destruction of these two components that leads to limbus insufficiency syndrome.

Prostate saturation biopsy in the reevaluation of microfocal prostate cancer.

PURPOSE: We evaluated the ability of an extended, 32-core repeat transrectal ultrasound prostate biopsy protocol to improve the characterization of low volume, well differentiated disease in men with a diagnosis of potentially insignificant microfocal prostate cancer, as defined by 1 single focus positive core of 10 with less than 5 mm of Gleason score 6 or less tumor on primary biopsy. MATERIALS AND METHODS: A total of 35 consecutive patients, who were 62 to 75 years old, had a median serum prostate specific antigen of 8 ng/ml (range 0.5 to 14) and a diagnosis of minimal prostate cancer, and were willing to consider observation with delayed treatment at progression, were offered repeat saturation prostate biopsy with a median of 32 cores (range 18 to 36) under local anesthesia. This biopsy was to determine whether more extensive prostate sampling would confirm or disprove the initial diagnosis of microfocal, well differentiated prostate cancer. RESULTS: The procedure was aborted in 1 patient because of massive rectal hemorrhage. Another patient had acute prostatitis with gram-negative sepsis. Of 34 evaluable biopsy sets 11 (32%) were negative for cancer, suggesting that tumor detected at the primary biopsy was probably of low volume and amenable to observation with delayed treatment. Of the biopsies 23 (68%) were positive, 17 were at multiple sites and 7 were upgraded to Gleason score 7 or greater. These patients were then considered to have significant tumors and were offered active treatment. CONCLUSIONS: This study is to our knowledge the first to describe the clinical use of prostate saturation biopsies for re-evaluating potentially insignificant prostate cancer. Of patients with minimal disease on standard 10-core biopsy, results show that this technique may be helpful for distinguishing the 30% who probably have minimal disease based on negative repeat saturation biopsy from the 70% who almost certainly have a significant tumor, as characterized by multiple positive cores, with or without an increased Gleason score. The latter patients should be offered active therapy.

Micro-focal prostate cancer: a comparison of biopsy and radical prostatectomy specimen features.

OBJECTIVES: To study the pathologic features of radical prostatectomy (RP) specimens of patients operated on the basis of a potentially "Insignificant" prostate cancer (Ca P) characterized by one single focus (less than 3mm) of moderately differentiated adenocarcinoma - Gleason score < or =6, out of 6-10 biopsies and to determine which characteristics, if any, are predictive of the presence of a "non significant" prostate cancer in the specimen characterized by a low volume (<0.5 ml) moderately differentiated organ confined, cancer (Gleason score less than 6). PATIENTS AND METHODS: PSA, biopsy features, and surgical specimens of a series of 56 patients submitted to RP for "insignificant Ca P" on TRUS prostate biopsies between 1988 and 2004 were compared regarding the number of tumor foci, Gleason grade and score, tumor volume determined by the cylinder method, as well as extraprostatic extension (EPE) and positive surgical margins (P.SM.). RESULTS: 70% of the patients had multifocal microfocal cancer apart from the index tumor. The presence of grade 4 was ignored by the biopsy in 50% of the cases, however the primary grade was correctly evaluated in more than 70% of the biopsy sets. 42% of the patients had a cancer volume less than 0.5 ml and 29% met the definition of insignificant/unimportant cancer characterized by a moderately differentiated (Gleason score < or =6) of low volume (less than 0.5 ml) however no feature accurately predictive of insignificant cancer could be individualized. In this whole series, only 8% of the patients had EPE. When the pre-operative PSA was <10 ng/ml, 98% of the patients had an organ confined tumor. CONCLUSION: Patients diagnosed with prostate cancer on the basis of one single focus less than 3 mm of moderately differentiated (Gleason < or =6) prostate cancer have 30% of chances of harboring an insignificant tumor in their prostate and are therefore, at risk of being overtreated, however there is at this time no specific feature able to identify these patients pre operatively.

[Innervation of Denonvilliers' recto-vesical septum. Anatomic study]. / Innervation du septum recto-vésical de Denonvilliers. Etude anatomique.

OBJECTIVE: The retro vesical septum (DENONVILLIERS) can be dissected and separated of the prostate and the bladder. The neurovascular bundles bound laterally this septum and it must be removed during radial prostatectomy. The aim of this study was to know if this septum is crossed by nerves. MATERIAL AND METHODS: Dissection of cadaver--histological study of recto-vesical fascia. RESULTS: Nerves are present coming from the neurovascular bundle to the septum and end in the prostate. CONCLUSION: These anatomical observations conduct to recommend to remove systematically the recto-vesical septum during radical prostatectomy for cancer.

Renal carcinoma: diagnosis of venous invasion with Gd-enhanced MR venography.

The aim of this study was to evaluate the usefulness of gadolinium-enhanced time-of-flight magnetic resonance venography (MRV) in the diagnosis of bland thrombosis/tumoral invasion in the preoperative assessment of renal cell carcinoma. Preoperative precontrast and enhanced GRE fast lowangle shot (FLASH) images of 36 patients with renal adenocarcinoma were reviewed and compared with pre- and post-contrast T1-weighted images. All patients underwent surgery, and MR findings were blindly and prospectively compared with surgical and pathologic data, considered the standard. Renal vein and vena cava were involved in 17 and 9 patients, respectively; right atrial extension was present in one patient. Precontrast spin-echo (SE) and FLASH images were 88% sensitive and 100% specific in the detection of venous involvement, respectively, and enhanced FLASH images 100% sensitive and 96% specific. The nature of thrombus (neoplastic or bland) was more accurately assessed (McNemar's, p < 0.05) with FLASH-enhanced MR images (sensitivity 89%; specificity 96%) than with SE and precontrast FLASH images (sensitivity 79%; specificity 94%). Our data suggest that use of Gd-enhanced MRV might improve preoperative assessment of vascular involvement in renal carcinoma.

Extensive biopsy protocol improves the detection rate of prostate cancer.

PURPOSE: We evaluated improvement in the rate of prostate cancer detection when using an extensive biopsy protocol involving peripheral cores. MATERIALS AND METHODS: We prospectively evaluated 303 consecutive men who underwent transrectal ultrasound guided biopsy due to elevated prostate specific antigen (PSA) and/or abnormal digital rectal examination. Ten biopsies were performed, including at least 5 at the base and middle of each lobe. In addition to standard biopsy at a 45-degree angle, a more peripheral 30-degree angle biopsy was obtained. At the apex only 1 standard biopsy was done. However, when prostate volume was greater than 50 cm.3, an additional peripheral biopsy was obtained at the apex. RESULTS: The complication rate in this biopsy protocol was 1% (3 patients). Prostate cancer was detected in 118 of the 303 men (38. 9%). Overall this extensive protocol resulted in 6.6% improvement in the detection rate. Improvement was 6.5% in men with PSA 10 ng./ml. or less and 7% in those with PSA greater than 10 (not significant). CONCLUSIONS: Increasing the number of biopsy cores and improving prostate peripheral zone sampling resulted in a significant improvement in the detection of prostate cancer.

[Features of prostatic cancer in French individuals of African-Caribbean origin]. / Caractéristiques des cancers prostatiques chez les français d'origine afro-antillaise.

OBJECTIVES: To evaluate the clinical, laboratory and histological characteristics of prostate cancer at the time of diagnosis and after radical treatment in various ethnically different patient groups. PATIENTS AND METHODS: Prostatic biopsies were performed in 466 consecutive patients because of an abnormal digital rectal examination and/or isolated elevation of PSA (greater than 3 ng/ml). In this series, 40 patients were Black and 426 were Caucasian. The other aspect of the study concerns 320 patients undergoing radical prostatectomy for stage T1 T2 prostatic tumour (25 Black, 295 Caucasian). In the biopsied group, we analysed mean age, mean PSA, mean cancer length on biopsies and mean Gleason score. In the operated group, we studied preoperative characteristics, histological stage, resection margin status, laboratory progression (PSA greater than 0.05 ng/ml) and time to progression. RESULTS: At the time of diagnosis, the mean age was 61.4 years (48-73) for Blacks and 65.2 years (42-87) for Caucasians (p < 0.05). The median Gleason score was 7 in the two groups. The PSA was 13.4 (1.7-105) ng/ml versus 14.4 (0.4-600) ng/ml, respectively. The mean percentage of invaded tissue on biopsies was 24% versus 18.8% and the mean percentage of positive biopsies was 53% versus 39%, respectively. In the operated group, capsular effraction rates were 39% in Blacks and 48.1% in Caucasians. Positive resection margin rates were 21.7% versus 36.6%, respectively. The laboratory progression rate with a mean follow-up of 33 months (6-126) was identical in the 2 groups (42.1% versus 41.1%), but the time to progression was shorter for Blacks (9 months versus 12.3 months). CONCLUSIONS: In this patient series, Black patients had the same laboratory profile as Caucasian patients at the time of diagnosis. However, they were younger at the time of discovery of the disease, had more positive biopsies and more tumour-invaded tissue on biopsies, and Black patients undergoing radical prostatectomy developed laboratory recurrence more rapidly.

Percentage of cancer on biopsy cores accurately predicts extracapsular extension and biochemical relapse after radical prostatectomy for T1-T2 prostate cancer.

PURPOSE: To perform a multivariate analysis to investigate the usefulness of eight preoperative variables as predictors of final pathological stage (pT), positive surgical margins (PSM) and biological progression after radical prostatectomy (RP). MATERIALS AND METHODS: In 143 patients undergoing RP for T1-T2 prostate cancer, the respective values of age, clinical stage, preoperative prostate-specific antigen (PSA), prostate-specific antigen density (PSAD), number of positive biopsies (NPB), Gleason score, length of tissue core invaded by cancer (LTI) and topography (uni/bilaterality) of positive biopsies for predicting extracapsular extension, PSM and biochemical failure (PSA> or =0.05 ng/ml) were evaluated retrospectively. Univariate and multivariate analyses were applied to define the statistical significance of each variable. Actuarial survival without biological progression was calculated using the Kaplan-Meier method (log-rank test). RESULTS: In this series, 44.8% of patients had extracapsular extension with 41.3% PSM. The mean PSA was 12.4 ng/ml. In univariate analysis, LTI (p<0.0001), NPB (p = 0.0023), PSA (p = 0.0039) and Gleason score (p = 0.0136) were the most powerful variables to predict pT stage; however, in logistic regression analysis, LTI was the most predictive feature. For prediction of PSM, some variables (LTI, NPB and PSA) were found to be of statistical value in univariate analysis, and LTI in combination with NPB and PSA in multivariate analysis. For biological progression, statistical analysis (log rank test) showed PSAD and LTI to be significant predictors. CONCLUSION: The pathological report regarding the biopsy contains crucial information influencing the prediction of pT stage, PSM and biological progression after RP. LTI, NPB and PSA are the most useful parameters for this purpose.

[Innervation of Denonvilliers' recto-vesical fascia. Anatomical study]. / Innervation du fascia recto-vésical de Denonvilliers. Etude anatomique.

OBJECTIVE: Dissection of Denonvilliers' rectovesical fascia allows easy cleavage of the prostatorectal and prostatovesical spaces. Its lateral limit in the "neurovascular pedicles" justifies its resection during radical prostatectomy. The objective of this study was to define the course and to observe the structure of nerves crossing the rectovesical fascia, as the sheaths of these nerves may be invaded by prostatic adenocarcinoma tumour cells. MATERIAL AND METHODS: After dissection of a fresh cadavre to define the relations of this fascia with the pedicles, rectovesical fascia biopsies were taken during radical prostatectomies. Transverse sections were performed and examined histologically. RESULTS: Certain nerves, derived from the neurovascular pedicle of the inferior hypogastric plexus, cross the rectovesical fascia to innervate the prostate. CONCLUSION: This confirms the importance of complete resection of the rectovesical fascia during radical prostatectomy for cancer, not only for surgical reasons, but also to ensure oncologically satisfactory surgery, i.e. with healthy resection margins.

Absence of microsatellite instability in transitional cell carcinoma of the bladder.

OBJECTIVES: To investigate the prevalence of the microsatellite instability related to mismatch repair (MMR) gene defects using a panel of six microsatellite markers, as recommended by a recent workshop on microsatellite instability in colon cancer, because it is still unclear whether abnormalities in DNA MMR genes are involved in transitional cell carcinoma (TCC) of the bladder. METHODS: Three mononucleotide repeats (BAT26, TGFbetaRII, and BAX) were studied in 33 TCC samples and in four bladder cancer cell lines. Three dinucleotide repeats (D2S123, D5S346, and D17S250) were studied in 21 of these 33 TCC samples. RESULTS: No alteration was detected either in the 33 TCC samples analyzed or in the four bladder cancer cell lines (T24, J82, 647V, and 1207) studied. A difference between normal and tumor DNA was observed in only 1 of 21 tumor samples for D17S250. CONCLUSIONS: These data indicate that microsatellite instability is very uncommon in TCC of the bladder.

Diagnostic value of ten systematic TRUS-guided prostate biopsies.

OBJECTIVE: To evaluate the improvement in the rate of detection of prostate cancer using an extensive protocol involving ten transrectal biopsies. METHODS: A total of 162 patients submitted to transrectal ultrasound-guided biopsy for elevated prostate-specific antigen (PSA) and/or abnormality on digital rectal examination were studied consecutively and prospectively. Five biopsies were performed in each lobe: between the three standard biopsies on each side, two additional biopsy specimens were taken in the same plane and at the same 45 degrees angle. RESULTS: The complication rate with the ten-biopsy protocol was 1.85%. Prostate cancer was detected in 40.1% of the patients. In the overall series, the percentage of diagnostic improvement brought about by this ten-biopsy protocol was +3.1%. The percentage improvement was greatest (+4.9%) in patients with PSA

Immunoelectron microscopic study of the conjunctiva in cicatricial pemphigoid.

BACKGROUND: Immune deposits can be found on the conjunctival basement membrane zone of patients affected by cicatricial pemphigoid using immunofluorescence technique. The purpose of this study was to perform direct immunoelectron microscopy on the conjunctiva of patients with scarring conjunctivitis associated with cicatricial pemphigoid. METHODS: Conjunctival and skin biopsies were performed in six patients who presented with presumed autoimmune cicatrizing conjunctivitis associated with cicatricial pemphigoid. Specimens were processed for direct immunofluorescence and direct immunoelectron microscopy. RESULTS: Direct immunofluorescence was positive in all skin samples and in three of six conjunctival samples. Direct immunoelectron microscopy showed immune deposits in the lamina lucida and the lamina densa of all skin and conjunctival samples. CONCLUSIONS: Direct immunoelectron microscopy can be performed on the conjunctiva. It shows the precise localization of cicatricial pemphigoid target antigens within the conjunctival basement membrane zone.

[Recommendations for reforming prostatic specimens. Les Membres du Sous-Comité Prostate du Comité de Cancerologie de l'Association Française d'Urologie]. / Recommandations pratiques pour les prélèvements prostatiques. Les Membres du Sous-Comité Prostate du Comité de Cancerologie de l'Association Française d'Urologie.

The purpose of these recommendations proposed by the members of the <>, is to provide an informative report for the clinician and the pathologist, in the management of patients with prostate cancer. These recommendations are common to the ADSAP and UICC recommendations on prostate cancer. Standardized forms are recommended to be included in every report.

[Florid glandular cystitis: study of 3 cases and review of the literature]. / La cystite glandulaire floride: étude de trois cas et revue de la littérature.

The authors report three cases of florid, recurrent cystitis glandularis in white men, inducing dilatation of the upper urinary tract due to invasion of the ureteric meatus. Treatment consisted of cystectomy, with preservation of the prostatic capsule, allowing preservation of continence and sexual potency. Cystitis glandularis is a rare, generally asymptomatic, benign metaplasia; it is favoured by chronic irritation and is sometimes associated with pelvic lipomatosis. Its transformation into adenocarcinoma is exceptional and occurs in the case of persistence of the predisposing factor. However, annual surveillance by cystoscopy with bladder biopsies is necessary. The florid form is much rarer and more disabling and usually requires wide resection of the lesions.

Radical prostatectomy for prostate cancer: the perineal approach increases the risk of surgically induced positive margins and capsular incisions.

PURPOSE: We compare the incidence of positive surgical margins in patients who underwent perineal or retropubic radical prostatectomy for clinically localized (stage T1, T2) prostate cancer. MATERIALS AND METHODS: In this retrospective, nonrandomized study we reexamined the specimens of 94 consecutive patients who underwent radical perineal (48) or retropubic (46) prostatectomy for clinically localized prostate cancer (stage T1, T2) and with pathological stage pT2 (intracapsular), pT3A (established extracapsular extension without positive margins) or pT3B (extracapsular extension with positive margins) without lymph node involvement (N0). We assessed the presence or absence of extracapsular cancer with or without positive margins, incisions of the prostatic capsule exposing cancer (surgically induced positive margins) or benign glandular tissue. Patients were followed for 3 to 66 months (mean 25) using an ultrasensitive prostate specific antigen assay with a lower detection limit of less than 0.05 ng./ml. RESULTS: The overall incidence of positive margins in cancer tissue was 56% in the perineal and 61% in the retropubic group, and biochemical failure-free survival was 67% each. However, surgically induced positive margins in patients with organ confined disease were more frequent in the perineal than retropubic group (43 versus 29%, p < 0.05) and associated with a 37% risk of biochemical failure (prostate specific antigen greater than 0.1 ng./ml.) at mean followup. In addition, capsular incisions exposing benign tissue were more frequent in the perineal than retropubic group (90 versus 37%, p < 0.05) irrespective of pathological stage. CONCLUSIONS: Although overall positive margins and biochemical failure rates are similar or identical for the perineal and retropubic approaches for organ confined prostate cancer, the perineal approach is associated with a significantly higher risk of capsular incisions and surgically induced positive margins and, thus, a higher risk of biochemical failure.

[Complete perineal prostatectomy carries an increased risk of capsular incision in healthy and cancerous tissue]. / La prostatectomie totale périnéale expose à un risque accru d'incision capsulaire en tissu sain et tumoral.

OBJECTIVES: To compare positive resection margin rates in tumour tissue and healthy tissue according to whether total prostatectomy for cancer is performed via a retropubic or transperineal approach. PATIENTS AND METHODS: This retrospective, non-randomized study was based on 94 patients suffering from clinically localized cancer (T1-T2) of the prostate operated either via a retropubic (46: group 1) or perineal (48: group II) approach. All slides were reviewed by two pathologists not informed about the clinical course. The frequency of tumour margins associated with extracapsular invasion, capsular incision, without extracapsular extension of the tumour, and finally the incidence of capsular incisions exposing tumour tissue, were determined. RESULTS: While the number of positive resection margins was equivalent in the two groups (61% for group I versus 56% for group II), it was higher in the perineal group (43% versus 29%, p < 0.05) when the tumour was confined to the gland (pT2). A higher incidence of resection margins in healthy tissue was also observed in group II (90% versus 37%). CONCLUSION: Transperitoneal prostatectomy is associated with a higher incidence of resection margins in tumour tissue in patients with prostate-confined cancer. Analysis of the resection margins in healthy tissue suggests that the surgical incision is a predisposing factor to their creation.

[Diagnostic value of 10 systematized and ultrasound-guided transrectal prostatic biopsies]. / Valeur diagnostique de dix biopsies prostatiques systématisées et échoguidées par voie transrectale.

OBJECTIVE: To study the improvement of prostatic cancer detection provided by ten strictly systematized transrectal prostatic biopsies. MATERIAL AND METHODS: This prospective study was conducted in 162 patients submitted to a series of 10 ultrasound-guided transrectal prostatic biopsies due to the presence of elevated PSA and/or an abnormality on digital rectal examination. Five biopsies were taken from different sites in each lobe: 2 biopsies were inserted between the 3 biopsies usually performed in the standard protocol, while maintaining the angle of entry of the needle recommended in this protocol. RESULTS: The complication rate was 1.85% with the 10-biopsy technique. Prostatic cancer was detected in 40.1% of the 162 patients. The percentage diagnostic improvement provided by the 10-biopsy protocol in the overall patient population was +3.1% compared to the standard protocol. The highest percentage diagnostic improvement was observed in the group of patients with PSA < or = 10 ng/ml (+4.9%) and in the group of patients with an ultrasound prostatic volume < or = 40 cc (+4%). CONCLUSION: The most marked diagnostic improvement appears to be related more to sampling of prostatic zones presenting a statistically increased risk of cancer (peripheral zone) than to the increased number of prostatic biopsies performed.

Adjuvant radiation therapy for recurrent PSA after radical prostatectomy in T1-T2 prostate cancer.

To evaluate retrospectively the efficacy of adjuvant radiation therapy (ART) in patients with T1-T2 prostate cancer (CaP) in whom extracapsular cancer (pT3) was detected after radical prostatectomy (RP), together with biochemical failure characterized by a recurrent level of serum prostate-specific antigen (PSA)>0.1 ng/mL. Twenty-two patients with T1-T2 CaP treated by RP who subsequently were found to have pT3 CaP with (13) or without (9) positive surgical margins and/or seminal vesicle invasion, exhibited biochemical failure characterized by a recurrent level of serum PSA, 2-40 (mean: 25) months after RP and were treated with ART (65 Gy). Bone and CT scans were negative in every patient, 15 of whom were submitted to TRUS biopsy (Bx) of the anastomosis (resection site), which was positive in 8. Patients were followed up for between 6 and 60 (mean: 32.5) months. Transient side effects (urgency, proctitis, diarrhea) were experienced by 9 patients after ART. A decrease in serum PSA was observed in 19 patients; however, only 14 of these achieved an undetectable level (<0.1 ng/mL) on one or more occasions after completion of ART (in 12 cases this was after 3 months). Of the 14 patients, 8 achieved a persistently unmeasurable PSA level at a mean follow-up of 20.4 (range: 9-48) months. There was no difference between patients in whom an undetectable level of serum PSA was attained and those in whom it was not, with regard to specimen pathology, PSA doubling time, timing of ART, and the result of Bx. Patients who achieved an undetectable PSA had a lower mean PSA at the time of ART (1.1 vs 2.9 ng/mL, P<0.05) and a lower preoperative mean PSA. Although ART for biochemical failure after RP may lead to undetectable PSA levels in a significant proportion of patients for a significant period of time, a longer follow-up shows that such unmeasurable levels persist in only 36.4% of such patients.

Renal chromophobe cell carcinoma and oncocytoma. A comparative morphologic, histochemical, and immunohistochemical study of 124 cases.

BACKGROUND: Renal oncocytoma has several features that overlap with other renal neoplasms, including the eosinophilic subtype of chromophobe cell carcinoma. In fact, strict criteria for renal oncocytoma have not been well defined and remain a matter of controversy. Ultrastructural studies or sophisticated methods such as flow cytometry and cytogenetic techniques can be of great use in distinguishing the two tumors, but are difficult to propose as routine methods because of their limited availability. OBJECTIVE: To further characterize the histologic criteria of these tumors, we undertook a retrospective study to define the utility of routinely available histochemical and immunohistochemical techniques. DESIGN AND SETTING: Twenty-one cases of chromophobe cell carcinoma, eosinophilic subtype, and 103 cases of oncocytoma were tested with histochemical (Perls, periodic acid-Schiff, and Hale's colloidal iron) and immunohistochemical (peanut agglutinin antigen and UEA-1 for lectins; cytokeratin KL1, epithelial membrane antigen, vimentin, S100 protein, and lysozyme) staining. RESULTS: The antibodies tested and the histochemical staining using Hale's colloidal iron allowed eosinophilic chromophobe cell carcinoma to be distinguished by its characteristic reaction pattern. Seventy-six percent of the chromophobe cell carcinomas showed a microvacuolated pattern, and 89% of the renal oncocytomas showed an apical positivity with Hale's colloidal iron staining (P < .01). Peripheral cell accentuation reactivity for cytokeratin KL1 was observed in 66% of the chromophobe cell carcinoma cases, and apical cytoplasmic positivity was observed in 37% of the renal oncocytoma cases (P = .01). Significant patterns were observed with anti-epithelial membrane antigen and anti-peanut agglutinin antigen antibodies (P = .05 and P = .01, respectively). Positive reactions for vimentin, S100 protein, lysozyme, and UEA-1 were not significant characteristics. CONCLUSION: Our study demonstrated that a precise morphologic description associated with simple histochemical and immunohistochemical techniques provides sufficient criteria for a high level of discrimination between the eosinophilic subtype of chromophobe cell carcinoma and renal oncocytoma.