CD10 is expressed in a subset of chromophobe renal cell carcinomas

Clear Cell Carcinomas of Müllerian Type and Rete Testis Origin Presenting as Scrotal Masses: A Study of Seven Cases

Ovarian-type epithelial tumors involving the testis and paratestis are rare, with clear cell carcinomas (CCC) one of the least frequent. We report our experience with 4 müllerian-type (MT) CCCs presenting as testicular/scrotal masses and arising in the paratestis (n=2) and seminal vesicle (n=2; well supported in 1 case and likely in the other). In addition, we document 3 cases of papillary CCC exclusively within the rete testis (RTCCC) and seminiferous tubules and differing from the MT tumors. The patients with MTCCC were 24 to 85 years old (median, 42 y), and 2 had metastases at presentation. The 2 originating in the paratestis were associated with other MT tumors, an endometrioid borderline tumor and a papillary serous borderline tumor. The other 2 MTCCCs likely involved the testis via extension from seminal vesicle primaries through the vasa deferentia. All MTCCCs showed typical features, including tubules, simple papillae with hyalinized cores, and solid nests of polygonal clear cells with occasional hobnail features. Both paratesticular primaries showed sarcomatoid foci with tumor-associated neutrophilic infiltrates. The 3 RTCCCs presented in 54-, 57-, and 60-year-old men as testicular masses; they showed intrarete arborizing papillary growth with nonhyalinized fibrous cores and piled-up, solid foci, lacked hobnail cells, and expressed carbonic anhydrase IX (2/2) and CD10 (2/2) but not CA125, unlike the MTCCCs. On follow-up, 2 patients with MTCCC died of metastatic tumor (4 and 13.5 mo), a third developed ileal and retroperitoneal metastases at 13 months; and the fourth died at 13.5 months of unspecified cause. Follow-up of 2 patients with RTCCCs showed 1 disease free at 8 months and another alive with unknown disease status at 13 years. We conclude that CCCs involving the testis may either be of MT with often aggressive courses or show some features of renal tumors, with confinement to the rete testis and indolent behavior.

Therapeutic Response to PRRNT in a Rare Case of Metastatic Renal Neuroendocrine Carcinoma

Neuroendocrine tumors (NETs) are a rare spectrum of neoplasms that are characterized by neuroendocrine and neural differentiation. The treatment can be challenging in view of the heterogeneity in differentiation and behavior. Primary renal origin NETs are rare and only a few cases have been reported in the literature. There is limited knowledge on their presentation and response to various lines of treatment. We report a case of a patient with a metastatic renal NET from a rare histological subtype of large cell neuroendocrine carcinoma, known to cause aggressive disease with poor prognosis. A multimodality treatment approach was followed. In spite of surgical management and second-line chemotherapy, the disease progressed. The patient subsequently received peptide receptor radionuclide therapy (PRRNT) using lutetium-177 DOTATATE, following which the patient demonstrated a remarkable clinical and radiological response and is stable to date. In a rare tumor with poor prognosis, the relevance of theranostics and the efficacy of targeted therapies like PRRNT are noteworthy.

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.

WHO 2022 landscape of papillary and chromophobe renal cell carcinoma

The 5th edition of the WHO Classification of Tumours of the Urinary and Male Genital Systems contains relevant revisions and introduces a group of molecularly defined renal tumour subtypes. Herein we present the World Health Organization (WHO) 2022 perspectives on papillary and chromophobe renal cell carcinoma with emphasis on their evolving classification, differential diagnosis, and emerging entities. The WHO 2022 classification eliminated the type 1/2 papillary renal cell carcinoma (pRCC) subcategorization, given the recognition of frequent mixed tumour phenotypes and the existence of entities with a different molecular background within the type 2 pRCC category. Additionally, emerging entities such as biphasic squamoid alveolar RCC, biphasic hyalinising psammomatous RCC, papillary renal neoplasm with reverse polarity, and Warthin-like pRCC are included as part of the pRCC spectrum, while additional morphological and molecular data are being gathered. In addition to oncocytomas and chromophobe renal cell carcinoma (chRCC), a category of 'other oncocytic tumours' with oncocytoma/chRCC-like features has been introduced, including emerging entities, most with TSC/mTOR pathway alterations (eosinophilic vacuolated tumour and so-called 'low-grade' oncocytic tumour), deserving additional research. Eosinophilic solid and cystic RCC was accepted as a new and independent tumour entity. Finally, a highly reproducible and clinically relevant universal grading system for chRCC is still missing and is another niche of ongoing investigation. This review discusses these developments and highlights emerging morphological and molecular data relevant for the classification of renal cell carcinoma.

Immunohistochemistry for the diagnosis of renal epithelial neoplasms

Despite the increasing number of newly identified renal neoplasms, the diagnosis of renal cell carcinoma (RCC) can usually be reached with careful histologic examination and a limited immunohistochemical (IHC) panel. Clear cell, papillary, chromophobe RCC and oncocytoma account for more than 90% of renal neoplasia in adults, and sophisticated ancillary tools are usually unnecessary. Renal tumors with entity-defining genetic alterations may ultimately require molecular confirmation via cytogenetics or sequencing technologies, such as RCC with TFE3, TFEB, or ALK gene rearrangements, or TFEB amplified RCC. In fumarate hydratase-deficient and succinate dehydrogenase-deficient RCC, highly specific IHC markers can strongly suggest the diagnosis. In the metastatic setting, PAX8 and carbonic anhydrase 9 are among the most helpful markers for confirming RCC and clear cell type, respectively; however, caution should be exercised in the absence of a current or historical renal mass. In diagnostically challenging cases, such as renal eosinophilic tumors with low-grade nuclear features, or infiltrative high-grade tumors, careful examination coupled with a judicious panel of IHC markers usually resolves the diagnosis. This review offers concise algorithms for diagnosis of kidney neoplasia with the latest recognized, provisional, and emerging entities to daily pathology practice.

Parvalbumin immunohistochemical expression in the spectrum of perivascular epithelioid cell (PEC) lesions of the kidney

Parvalbumin is a cytosolic calcium-binding protein expressed in the distal convoluted tubule of the renal nephron. Among epithelial renal tumors, the reactivity for parvalbumin is observed in chromophobe renal cell carcinomas and frequently in oncocytomas. On the other hand, there are no data available on parvalbumin expression in the mesenchymal tumors of the kidney. Therefore, the purpose of this study was to evaluate the expression of parvalbumin in the spectrum of PEC (perivascular epithelioid cells) lesions of the kidney. Sixty-six PEC lesions (37 classic angiomyolipomas, 10 microscopic angiomyolipomas, 7 epithelioid angiomyolipomas/pure epithelioid PEComas, 5 leiomyoma-like angiomyolipomas, 3 lipoma-like angiomyolipomas, 2 intraglomerular lesions, 1 angiomyolipoma with epithelial cysts (AMLEC), and 1 sclerosing angiomyolipoma) were immunohistochemically stained with parvalbumin. Overall, parvalbumin immunostain was found in fifty-six PEC lesions (85%) and absent in the remaining ten cases (15%). Classic angiomyolipomas were positive in almost all cases (97%). Intraglomerular lesions and AMLEC showed parvalbumin immunolabeling as well. None of the 7 epithelioid angiomyolipomas/pure epithelioid PEComas or the only sclerosing angiomyolipoma expressed parvalbumin. In conclusion, we demonstrated the immunolabeling of parvalbumin in almost all PEC lesions of the kidney, but not in the epithelioid angiomyolipoma/pure epithelioid PEComa. This finding could shed light on some biological characteristics observed in the PEC lesions such as the plasticity of their cellular component. Moreover, parvalbumin may be another useful tool in the differential diagnosis among epithelioid angiomyolipoma/pure epithelioid PEComa with other renal eosinophilic tumors, such as oncocytoma and chromophobe renal cell carcinoma.

Chromophobe renal cell carcinoma: current and controversial issues

It has been 35 years since Professor Thoenes and his colleagues discovered chromophobe renal cell carcinoma (RCC). Since then, our knowledge about this tumour entity has changed and novel tumour entities have been discovered. The aim of this review is to discuss recent molecular findings and open questions in diagnosing chromophobe-like/oncocytic neoplasms. The broader differential diagnosis of chromophobe-like and oncocytoma-like neoplasms includes SDH-deficient renal cell carcinoma, fumarate hydratase (FH) deficient RCC, epitheloid angiomyolipoma ('oncocytoma like'), MiT family translocation RCC and the emerging entity of eosinophilic solid and cystic renal cell carcinoma. After separation of these tumours from chromophobe RCC, it becomes evident that chromophobe RCC are low malignant tumours with a 5-6% risk of metastasis. Recent next generation sequencing (NGS) and DNA methylation profiling studies have confirmed Thoenes' theory of a distal tubule derived origin of chromophobe RCC and renal oncocytomas. Comprehensive genomic analyses of chromophobe RCC have demonstrated a low somatic mutation rate and identified TP53 and PTEN as the most frequently mutated genes, whereas 'unclassified' RCC with oncocytic or chromophobe-like features can show somatic inactivating mutations of TSC2 or activating mutations of MTOR as the primary molecular alterations. For the future, it would be desirable to create a category of 'oncocytic/chromophobe RCC, NOS' with the potential of further molecular studies for identification of TSC1/2 mutations in these rare tumours.

HNF-1β as an immunohistochemical marker for distinguishing chromophobe renal cell carcinoma and hybrid oncocytic tumors from renal oncocytoma

The histologic features of renal oncocytoma (RO) are similar to those for the more aggressive chromophobe renal cell carcinoma (ChRCC). To assess immunohistochemical markers of the two, the sensitivity and specificity of cytokeratin 7 (CK7) and C-kit, as well as hepatocyte nuclear factor-1β (HNF-1β), were analyzed. Typical cases of ChRCC and RO at Severance Hospital between July 2014 and July 2018 were selected retrospectively. Among 44 cases, 17 were unanimously compatible with ChRCC, 16 were RO, and 11 cases were indeterminate. Samples from all selected cases were used for immunostaining with antibodies against CK7, C-kit, HNF-1β, and CD10. Immunostaining demonstrated complete loss of HNF-1β expression in 11 out of 17 (64.7%) ChRCC cases and a partial, but significant loss in > 50% of tumor cells in the remaining 6 cases (35.3%). In contrast, HNF-1β expression was preserved in tumor cells of RO cases. Fourteen of 17 ChRCC cases (82.4%) were diffusely positive for CK7, whereas cases of RO were focal positive or negative. C-kit staining did not show a significant difference between ChRCC and RO. Two of five ChRCC cases showing diffuse immunoreactivity for CD10 had poor prognoses of local invasion, distant metastasis, or death. Loss of HNF-1β expression is a useful marker with which to diagnose ChRCC, especially in cases with confusing histologic findings or equivocal CK7 staining. Additionally, CD10 staining in high-grade ChRCC aids in diagnosis and prediction of the clinical prognosis.

Proximal CD13 Versus Distal GATA-3 Expression in Renal Neoplasia According to WHO 2016 Classification

Little is known about the aminopeptidase CD13 in renal neoplasia according to the new 2016 World Health Organization renal tumor classification. We selected 175 cases, including 79 clear cell, 31 papillary, 24 chromophobe, 8 clear cell papillary renal cell carcinomas (RCCs), 21 oncoytomas, and 12 microphthalmia transcription factor family translocation RCCs: 4 t(6;11)/transcription factor EB (TFEB), 7 t(Xp11) with 2 cystic variants and 1 t(X;17). GATA binding protein 3 (GATA-3) was inserted as control. Expression of proximal antigen CD13 was observed in 63/79 (80%) clear cell, 25/31 (81%) papillary, 3/8 (37%) clear cell papillary, 1/4 (25%) t(6;11)/TFEB, 2/7 (28%) cystic t(Xp11), and in 1/1 t(X;17) RCCs. All chromophobe RCC (0/24) and all oncocytomas (0/21) resulted negative. CD10 was seen in 76/79 (96%) clear cell, 15/31 (48%) papillary, 10/24 (42%) chromophobe, 1/8 (12%) clear cell papillary RCCs, 4/21 (19%) oncocytomas, 1/4 (25%) t(6;11)/TFEB, 2/7 (29%) cystic t(Xp11), and in 1/1 t(X;17) RCCs. GATA-3 was positive in 3/7 (42%) clear cell papillary RCCs and negative in all remaining RCCs, except a single chromophobe RCC and a single oncocytoma. We concluded that: (1) CD13 and GATA-3 immunostains may serve as a diagnostic aid in differentiating subtypes of RCC; (2) CD13 is always absent in chromophobe RCC and oncocytomas, whereas CD10 can be immunoexpressed in both; (3) CD13 should be included in a panel of antibodies to distinguish "proximal renal tumors" from "distal renal tumors" and between clear cell RCC versus microphthalmia transcription factor family translocations RCCs; and (4) when present, GATA-3 is specific for clear cell papillary RCC.

A Phage Display-Identified Peptide Selectively Binds to Kidney Injury Molecule-1 (KIM-1) and Detects KIM-1-Overexpressing Tumors in vivo

PURPOSE

This study was carried out to identify a peptide that selectively binds to kidney injury molecule-1 (KIM-1) by screening a phage-displayed peptide library and to use the peptide for the detection of KIM-1overexpressing tumors in vivo.

MATERIALS AND METHODS

Biopanning of a phage-displayed peptide library was performed on KIM-1-coated plates. The binding of phage clones, peptides, and a peptide multimer to the KIM-1 protein and KIM-1-overexpressing and KIM-1-low expressing cells was examined by enzyme-linked immunosorbent assay, fluorometry, and flow cytometry. A biotin-peptide multimer was generated using NeutrAvidin. In vivo homing of the peptide to KIM-1-overexpressing and KIM1-low expressing tumors in mice was examined by whole-body fluorescence imaging.

RESULTS

A phage clone displaying the CNWMINKEC peptide showed higher binding affinity to KIM-1 and KIM-1-overexpressing 769-P renal tumor cells compared to other phage clones selected after biopanning. The CNWMINKEC peptide and a NeutrAvidin/biotin-CNWMINKEC multimer selectively bound to KIM-1 over albumin and to KIM-1-overexpressing 769-P cells and A549 lung tumor cells compared to KIM-1-low expressing HEK293 normal cells. Co-localization and competition assays using an anti-KIM-1 antibody demonstrated that the binding of the CNWMINKEC peptide to 769-P cells was specifically mediated by KIM-1. The CNWMINKEC peptide was not cytotoxic to cells and was stable for up to 24 hours in the presence of serum. Whole-body fluorescence imaging demonstrated selective homing of the CNWM-INKEC peptide to KIM-1-overexpressing A498 renal tumor compared to KIM1-low expressing HepG2 liver tumor in mice.

CONCLUSION

The CNWMINKEC peptide is a promising probe for in vivo imaging and detection of KIM-1‒overexpressing tumors.

[The morphological and molecular genetic characteristics of sarcomatoid chromophobe renal cell carcinoma]

The paper describes a case of chromophobe renal cell carcinoma growing into the muscular layer of the descending colon and with metastases in 4 lymph nodes of paranephral tissue in a 66-year-old woman. The tumor had a zonal structure with an alternation of epithelioid and sarcomatoid structural sites and with the signs of grades I, II and III according to the grading system by Paner and et al. (2010). The sarcomatoid renal component occupied about 70.0% of the tumor. There was a pronounced immunohistochemical reaction with VEGF-A (5 scores), a high Ki-67 proliferation index (70%), and a large number of tumor cells with nuclear p53 expression (85%) in the areas with minimal differentiation and sarcomatoid elements (Grade III). These signs can serve as criteria for the aggressive behavior of the tumor. A large volume of the sarcomatoid carcinoma component and a strong reaction with VEGF-A are indications for targeted therapy with anti-VEGF drugs.

Expression Analysis of Wnt-5a in Renal Epithelial Neoplasms: Distinguishing Renal Oncocytoma from a Wide Spectrum of Renal Cell Carcinomas

Objective

To study the expression of a novel marker, Wnt-5a, in renal epithelial neoplasms and determine its clinicopathological significance.

Methods

Immunohistochemical analysis of Wnt-5a was carried out in normal human kidney samples as well as in 123 primary renal epithelial neoplasms including 37 clear cell renal cell carcinomas (RCCs), 24 papillary RCCs (15 type 1 and 9 type 2), 25 chromophobe RCCs, 11 Xp11 translocation carcinomas, 6 mucinous tubular and spindle cell carcinomas, and 20 oncocytomas.

Results

Wnt-5a was expressed in 18.9% (7/37) of clear cell RCCs, 12.5% (3/24) of papillary RCCs, 16% (4/25) of chromophobe RCCs, 18.2% (2/11) of Xp11 translocation carcinomas, 0% (0/6) of mucinous tubular and spindle cell carcinomas, and 100% (20/20) of oncocytomas. There was a significant difference in Wnt-5a immunohistochemistry between renal oncocytoma and the other subtypes of RCC (P <0.01).

Conclusions

Our results indicate that Wnt-5a is a potentially useful immunohistochemical marker for the complex differential diagnosis between oncocytoma and other subtypes of RCC and also suggest that Wnt-5a may be a tumor suppressor gene in RCC.

Epididymis-like Tubules in Adult Renal Hypodysplasia: Immunohistochemical Features Indicate a Mesonephric Origin

We report the presence of epididymis-like tubules in unilateral renal hypodysplasia in 3 adult men. Microscopy showed dilated tubules lined by ciliated columnar epithelium and smaller basal cells, morphologically resembling epididymal tubules. Small tubules lined by cuboidal epithelium were also present in all cases, with glomeruli in 2 cases. The epididymis-like tubules expressed CD10, CK7, PAX8, and AR in the luminal epithelium, while the basal cells were positive for p63, CK7, and focally for CD10. The smooth muscle bundles around the epididymis-like tubules were focally AR and WT1 (cytoplasmic) positive. The epididymis-like tubules were negative for ER, PR, and WT1. CK7 and PAX8 stained all the collecting ducts, with AR staining some. Bowman's capsule, parietal and visceral epithelial cells expressed CD10; WT1 stained the visceral and parietal epithelial cells. Glomerular parietal cells expressed PAX8 and focally, CK7. Proximal tubules were positive for CD10 (luminal membranous and weak cytoplasmic). Distal tubules expressed CK7, PAX8 and AR. An occasional small tubule was ER positive. Scattered stromal cells expressed ER, PR, and AR. The urothelium of the renal pelvis/upper ureter expressed CK7 in all layers, CD10 in the superficial layers, PAX8 in the basal layers and p63 in all layers except the umbrella layer. The epididymis-like tubules replicate the pattern of the mesonephros-derived normal epididymis in expressing CK7, PAX8, CD10, and AR. This supports a mesonephric rather than metanephric origin for these tubules. The aberrant expression of some markers may be a manifestation of the dysplastic nature of the kidneys.

Renal cell carcinoma metastatic to the ovary or fallopian tube: a clinicopathological study of 9 cases

Renal cell carcinoma (RCC), the most common type of kidney cancer in adult, rarely metastasizes to the ovary or fallopian tube, and most cases published in the literature were case reports. Herein, we describe the clinicopathological features of 9 cases of RCC metastatic to the ovary (n = 8) or the fallopian tube (n = 1). The patients' age at the onset of primary renal tumor was available in 8 patients, ranging from 37 to 73 years (mean, 51 years; median, 50 years). Ovarian metastasis was detected prior to or concurrently with the primary renal tumors in 3 patients, and after the diagnosis of renal tumors in 6 patients. The histotypes of the RCCs were clear cell (n = 7), chromophobe (n = 1), and unclassified (n = 1). Immunohistochemical stainings were performed on the sections containing metastatic tumors in 4 cases. Interestingly, pagetoid intraepithelial spread in the tubal mucosa was observed in the case of RCC metastatic to the fallopian tube. Among the 8 patients with follow-up data, 5 died of disease and 3 were alive with disease, with a follow-up period ranging from 3.7 months to 17 years (mean, 77 months; median, 53 months) after the diagnosis of primary kidney tumors. Diagnostically, metastatic RCC may mimic primary ovarian tumors clinically, morphologically, or immunophenotypically. Pathologists should also keep in mind that both ovarian and kidney tumors express PAX8 and PAX2, the markers commonly used to diagnose metastatic RCC. In addition, chromophobe RCC only rarely metastasizes, but it can be a diagnostic challenge when it metastasizes to the ovary.

Immunohistochemistry in dermatopathology

CONTEXT

Immunohistochemistry is not a diagnostic test but a highly valuable tool that requires interpretation within a context.

OBJECTIVE

To review the current status and limitations of immunohistochemistry in dermatopathology.

DATA SOURCES

English-language literature published between 1980 and 2014.

CONCLUSIONS

Although immunohistochemistry is rarely completely specific or sensitive, it is an important adjunctive technique in dermatopathology and can be helpful in a series of diagnostic dilemmas.

Renal function in angiotensinogen gene-mutated renal tubular dysgenesis with glomerular cysts

BACKGROUND

Inherited renal tubular dysgenesis (RTD) is caused by mutations in the genes encoding the components of the renin-angiotensin system (RAS). RTD is characterized by oligohydramnios, renal failure, neonatal hypocalvaria, and severe hypotension. The histological characteristics, underlying mechanism, and long-term prognosis remain poorly known.

CASE-DIAGNOSIS/TREATMENT

We describe here a 4-year-old female with RTD. Endocrinologic analysis showed a discrepancy between low plasma renin activity and high active renin concentration, suggesting a loss of the renin substrate, angiotensinogen (AGT). Direct sequencing revealed a frameshift deletion at nucleotide 1,355 in exon 5 in the AGT gene. Although a histological hallmark is regarded to be the absence or poor development of the proximal tubule, the patient does have minimally impaired function of the proximal tubule. Glomerular cysts without glomerular tufts were noted in approximately half of the glomeruli. The urinary concentrating ability and sodium reabsorption and potassium excretion in the distal nephron were severely affected.

CONCLUSIONS

The patient has an impaired function of the distal nephron despite minimally affected function of the proximal tubule, probably attributed to renal tubular dysgenesis and fetal hypoperfusion. The renal tubular maturity and the severity of ischemic injury may be key determinants of the clinical symptoms and pathological findings in RTD, in which the RAS plays an important role.

Renal cell carcinoma with smooth muscle stroma lacks chromosome 3p and VHL alterations

Renal cell carcinoma with prominent smooth muscle stroma is a rare neoplasm composed of an admixture of epithelial cell with clear cytoplasm arranged in small nest and tubular structures and a stroma composed of smooth muscle. In the epithelial component, loss of chromosome 3p detected by fluorescence in situ hybridization (FISH) has been reported and on this basis these neoplasms have been viewed as variants of clear cell renal cell carcinoma. To test the validity of this classification, we have evaluated the chromosome 3 and VHL status of three of these tumors using FISH, array comparative genomic hybridization, gene sequencing, and methylation-specific multiplex ligation-dependent probe amplification analysis. None of the tumors showed deletion of chromosome 3p, VHL mutation, a significant VHL methylation, or changes in VHL copy number and all three tumors demonstrated a flat profile in the comparative genomic hybridization analysis. We conclude that renal cell carcinoma with smooth muscle stroma should be considered as an entity distinct from clear cell renal cell carcinoma.

Renal tumors: diagnostic and prognostic biomarkers

The International Society of Urological Pathology convened a consensus conference on renal cancer, preceded by an online survey, to address issues relating to the diagnosis and reporting of renal neoplasia. In this report, the role of biomarkers in the diagnosis and assessment of prognosis of renal tumors is addressed. In particular we focused upon the use of immunohistochemical markers and the approach to specific differential diagnostic scenarios. We enquired whether cytogenetic and molecular tools were applied in practice and asked for views on the perceived prognostic role of biomarkers. Both the survey and conference voting results demonstrated a high degree of consensus in participants' responses regarding prognostic/predictive markers and molecular techniques, whereas it was apparent that biomarkers for these purposes remained outside the diagnostic realm pending clinical validation. Although no individual antibody or panel of antibodies reached consensus for classifying renal tumors, or for confirming renal metastatic disease, it was noted from the online survey that 87% of respondents used immunohistochemistry to subtype renal tumors sometimes or occasionally, and a majority (87%) used immunohistochemical markers (Pax 2 or Pax 8, renal cell carcinoma [RCC] marker, panel of pan-CK, CK7, vimentin, and CD10) in confirming the diagnosis of metastatic RCC. There was consensus that immunohistochemistry should be used for histologic subtyping and applied before reaching a diagnosis of unclassified RCC. At the conference, there was consensus that TFE3 and TFEB analysis ought to be requested when RCC was diagnosed in a young patient or when histologic appearances were suggestive of the translocation subtype; whereas Pax 2 and/or Pax 8 were considered to be the most useful markers in the diagnosis of a renal primary.

Chromophobe renal cell carcinoma: a morphologic and immunohistochemical study of 45 cases

The aim of this study was to evaluate the morphological spectrum of chromophobe renal cell carcinoma (CRCC) and diagnostic utility of a panel of three immunohistochemical stains. All cases of CRCC reported between 2002 and 2012 in the Section of Histopathology, Aga Khan University Hospital, were retrieved. A total of 45 cases were identified. Slides were reviewed and immunohistochemical stains (CK7, CD117, and vimentin) were performed. Ages ranged from 18 to 90 years (mean, 48.5 years). Male-to-female ratio was 0.8:1. The tumor was located in the left kidney in 24 patients and the right kidney in 20 patients. The tumor size ranged from 3.5 to 22 cm (mean 10 cm). Histologically, 4 were classic, 22 were eosinophilic, 16 were mixed, and 3 were sarcomatoid type. Morphologic patterns included broad alveolar, solid, nested, tubular, tubulocystic, trabecular, papillary, and microglandular. Binucleation and perinuclear halos were seen in all cases. Nuclear grooves and pseudoinclusions were seen in 17 and 6 cases, respectively. Multinucleated cells were seen in 19 cases. Mitoses ranged from 1 to 11/10 HPFs (mean 3/10 HPFs). Hyalinized stroma was seen in 38 cases and calcification in 26 cases. Necrosis was seen in 18 cases. Palisading of smaller cells around the broad alveolar pattern was noted in 5 cases. The Furhman's nuclear grade was I (11), II (26), III (5), and IV (3). Hale's colloidal iron was positive in all cases. Immunohistochemical stain CK7 and CD117 were positive in 100% and 95.5% of cases respectively. Vimentin was negative in all cases, except in the sarcomatoid areas of 3 cases. In conclusion, chromophobe renal cell carcinoma has certain unique morphological features and immunohistochemical profile which help to distinguish it from conventional renal cell carcinoma and oncocytoma. We identified nuclear pseudoinclusions, microglandular pattern and palisading of smaller cells, which have not been reported earlier.

Value of PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4 immunostaining in distinguishing pleural epithelioid mesothelioma from metastatic renal cell carcinoma

Both mesotheliomas and renal cell carcinomas can present a wide variety of cytomorphologic features and histologic patterns. Because of this, renal cell carcinomas metastatic to the pleura and lung can be confused with mesotheliomas. Recently, a variety of positive carcinoma markers, including kidney-associated markers, have become available. The aim of this study is to investigate the value of some of these markers, specifically PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4, for assisting in distinguishing pleural epithelioid mesotheliomas from metastatic renal cell carcinomas. To do so, a total of 40 pleural epithelioid mesotheliomas and 55 renal cell carcinomas (33 clear cell, 10 papillary, and 12 chromophobe) were investigated. In all, 91% of the renal cell carcinomas expressed claudin-4, 89% PAX8, 60% PAX2, 71% carbonic anhydrase IX, and 29% napsin A. All of the mesotheliomas were positive for carbonic anhydrase IX and were negative for all of the other markers. On the basis of these results, it is concluded that claudin-4 and PAX8 have a higher sensitivity and specificity for assisting in discriminating between pleural epithelioid mesotheliomas and renal cell carcinomas when compared with all of the other positive carcinoma markers that are, at present, recommended to be included in the immunohistochemical panels used in this differential diagnosis. Even though PAX2 and napsin A are highly specific, because of their low sensitivity, they have only a limited value. Carbonic anhydrase IX is not useful.

CD10 in the developing human kidney: immunoreactivity and possible role in renal embryogenesis

CD10 was first identified in tumor cells of acute lymphoblastic leukemia. Most studies on CD10 expression have dealt with tumor pathology. Since no data are available for specific role in the fetal kidney, this study aimed at investigating CD10 expression during the different phases of renal embryogenesis. To this end, the expression of CD10 was evaluated in the kidney of two human fetus and in three newborns. In both fetuses, immunostaining for CD10 was compartmentalized and mainly concentrated in the mid-deep cortex. Reactivity for CD10 was stronger in the glomerular epithelium, in proximal tubules and in metanephric mesenchymal cells. At 25 weeks of gestation, CD10 was also detected in the subcapsular regions, including some pretubular aggregates of cap mesenchymal cells and renal vesicles. At 34 weeks of gestation, we observed an increased immunoreactivity for CD10 in visceral and parietal glomerular epithelium. At 39 weeks of gestation, CD10 was also expressed in the collecting tubules and in the Henle loops. Our data show a strong expression of CD10 in all stage of human kidney development, characterized by dynamic changes and support the hypothesis that CD10 plays a relevant role in renal embryogenesis.

Malignant effusion of chromophobe renal-cell carcinoma: cytological and immunohistochemical findings

Malignant effusions because of renal-cell carcinoma (RCC) are an unusual event and occur in patients with papillary and clear cell tumors. We have studied a 65-year-old man who underwent right renal tumorectomy, diagnosed as chromophobe RCC (pT1). After 16 months, the patient presented cough and fever. Positron emission computed tomography demonstrated extensive mediastinal lymphadenopathy. Chest radiograph showed right pleural effusion. The cytological examination of the fluid showed malignant cells. Immunohistochemistry had been performed on primary renal tumor and on cell block of pleural effusion. The renal tumor showed positivity for parvalbumin, cytokeratin (CK) 7, C-kit (CD117), E-cadherin, and RCC marker. The neoplastic cells of pleural effusion showed positive immunohistochemical staining for parvalbumin, RCC marker, pancytokeratin, epithelial membrane antigen, CK7, C-kit (CD117), E-cadherin, and CD10. They were negative for thyroid transcription factor-1, CK20, calretinin, CK5, D2-40 podoplanin, CDX2, and Wilms' tumor suppressor gene. Malignant effusion secondary to RCC is rare. In several studies, RCC had been the cause of 1-2.2% of malignant pleural fluids. Chromophobe RCC tends to be localized into the kidney and to be of nuclear grade 2 at presentation, factors that probably explain its more favorable outlook. In our case, the chromophobe RCC was asymptomatic and was discovered because abdominal pain due to stone in the gallbladder. The tumor had an unusual aggressive clinical behavior. Immunohistochemistry performed on the cell block let to establish the renal origin and the chromophobe histotype of malignant cells found in the pleural fluid.

Chromophobe renal cell carcinoma with prominent lymph node metastasis and polysomy of chromosome 21: poorly differentiated form or "presarcomatoid" form?

Lymph node metastasis of chromophobe renal cell carcinoma (RCC) is extremely rare. It has been recently reported that sarcomatoid chromophobe RCC frequently show polysomy of chromosomes 1, 2, 6, 10, and 17. In this article, we report an unusual case of chromophobe RCC. A 42-year-old Japanese woman presented with hematuria and complained of inguinal pain 2 months after the initial symptoms. Radical nephrectomy and renal hilar lymphadenectomy were performed. The tumor was 8 cm in greatest diameter; its cut surface was beige in color. Large metastasis to the renal hilar lymph node was identified. Histological examination of the right renal tumor met the criteria of chromophobe RCC. In addition to histological findings of typical chromophobe RCC, small cell foci, comedo-like necrosis, trabecular growth pattern, and sclerosing stroma were observed. However, no sarcomatoid foci were identified anywhere, despite extensive tumor sampling including lymph node lesions. Immunohistochemically, neoplastic cells were positive for E-cadherin and CD117 (c-kit). Ultrastructurally, tumorous cells contained abundant mitochondria and cytoplasmic microvesicles. Fluorescence in situ hybridization showed monosomy of chromosomes 2 and 10 and polysomy of chromosome 21. Finally, we suggest that this tumor may show the poorly differentiated or presarcomatoid form of chromophobe RCC.

Chromophobe Renal Cell Carcinoma with Sarcomatoid Transformation in a Dog

A 12-year-old spayed female Siberian husky dog presented with hematuria and weight loss. An abdominal ultrasonographic examination revealed a left renal tumor measuring 8 cm in diameter, and a nephrectomy was performed. The resected kidney contained a cavitated tumor with a white solid region. Histologically, this tumor was composed of large polygonal cells with abundant and cloudy cytoplasm and focal sarcomatoid change. The neoplastic epithelial cells were reactive with colloidal iron staining; Dolichos biflorus agglutinin, peanut agglutinin, and Ulex europaeus agglutinin I lectins; and cluster of differentiation 10 and c-KIT antigens but not for periodic acid-Schiff or vimentin stain. Neoplastic sarcomatoid cells stained positive for vimentin. Because these histopathologic features are identical to those of human chromophobe renal cell carcinoma, the present case was diagnosed as canine chromophobe renal cell carcinoma.

Expression and activity profiles of DPP IV/CD26 and NEP/CD10 glycoproteins in the human renal cancer are tumor-type dependent

Background

Cell-surface glycoproteins play critical roles in cell-to-cell recognition, signal transduction and regulation, thus being crucial in cell proliferation and cancer etiogenesis and development. DPP IV and NEP are ubiquitous glycopeptidases closely linked to tumor pathogenesis and development, and they are used as markers in some cancers. In the present study, the activity and protein and mRNA expression of these glycoproteins were analysed in a subset of clear-cell (CCRCC) and chromophobe (ChRCC) renal cell carcinomas, and in renal oncocytomas (RO).

Methods

Peptidase activities were measured by conventional enzymatic assays with fluorogen-derived substrates. Gene expression was quantitatively determined by qRT-PCR and membrane-bound protein expression and distribution analysis was performed by specific immunostaining.

Results

The activity of both glycoproteins was sharply decreased in the three histological types of renal tumors. Protein and mRNA expression was strongly downregulated in tumors from distal nephron (ChRCC and RO). Moreover, soluble DPP IV activity positively correlated with the aggressiveness of CCRCCs (higher activities in high grade tumors).

Conclusions

These results support the pivotal role for DPP IV and NEP in the malignant transformation pathways and point to these peptidases as potential diagnostic markers.

Diagnostic usefulness of fluorescent cytogenetics in differentiating chromophobe renal cell carcinoma from renal oncocytoma: a validation study combining metaphase and interphase analyses

We investigated the usefulness of interphase fluorescence in situ hybridization (FISH) analysis to differentiate between 11 chromophobe renal carcinomas and 12 renal oncocytomas, showing different clinical outcomes, when compared with conventional metaphase cytogenetics by karyotyping. Karyotypically, 3 chromophobe renal cell carcinomas showed losses of chromosomes, 3 were polyploid, 1 was normal, and 4 failed to grow. Of 12 oncocytomas, 5 showed a normal numeric karyotype and 6 additional structural rearrangements. FISH on chromophobe renal cell carcinomas showed a high percentage of cases (10/11 [91%]) with multiple numeric losses among chromosomes 1, 2, 6, 10, and 17; this interphase pattern was observed irrespective of the 3 different metaphase karyotypes. Of 12 oncocytomas, 11 (92%) revealed a normal numeric chromosomal status showing at least 2 chromosomes without aneusomy by interphase FISH. The study demonstrates that indeed FISH performed on formalin-fixed, paraffin-embedded tissue can provide clinically useful information more reliably than karyotyping of most of these tumors.

Molecular diagnosis of renal cell neoplasms: the usefulness of immunohistochemistry and fluorescence in situ hybridization

BACKGROUND

The classification of renal cell neoplasms includes different subtypes of tumors characterized by different outcome. Some overlapping morphological features and the increasing recognition of new entities are making the traditional histologic distinction of renal cell neoplasms difficult and more tools improving the specificity of the correct identification are needed. Among molecular analyses, immunohistochemistry and fluorescence in situ hybridization have become the most helpful procedures, solving many issues in the differential diagnosis of the renal cell neoplasms.

OBJECTIVE

The aim of this review is to merge the large amount of recent knowledge regarding molecular markers of renal cell neoplasms into a helpful diagnostic algorithm.

CONCLUSION

It is proposed that immunoreactions for CD10, Alpha-methylacyl-CoA racemase, cytokeratin 7, parvalbumin and S100A1, and the cytogenetical analysis of chromosomes 3p, 1, 2, 6, 7, 10, 17 and Y can now offer the most specific tools for the classification of renal cell tumors.

[Ancillary studies in the differential diagnosis of epithelial renal cell tumors with granular cells]

INTRODUCTION AND OBJECTIVES

Differential diagnosis of renal neoplasms with granular cells may pose difficulties and implications on ontogeny and prognosis. Our aims are to characterize the pattern of immunostaining and to search for a useful diagnosis panel.

METHODS

We studied with colloidal iron staining (Mowry's modified method) and 22 commonly used immunomarkers 22 conventional carcinomas (CC), 37 chromophobe carcinomas (CPC), 8 oncocytomas (OC), and 7 collecting duct carcinomas (CDC) with granular cells. Cases with not entirely clear diagnosis were excluded.

RESULTS

Colloidal iron staining was diffuse, strong, reticular, and cytoplasmic in 32 CPC cases, the diffuse and strong pattern was not observed in other tumors. The more useful diagnostic panel was cytokeratin 7 (CK7)/CD10/vimentine (vim). The 8 OC were negative for the three antibodies. The most common profile for CC was CK7-/CD10+/vim+, the CPC profile was CK7+/CD10-/vim-, and CDC did not show a particular profile. With these three antibodies specificity was >90% for the differential diagnosis. Adding colloidal iron staining specificity was 100%.

CONCLUSIONS

Morphologic features, colloidal iron staining (modified Mowry's method), and immunostaining with CK7/CD10/vim permit the final diagnosis with high specificity. However, a 100% specific marker does not exist at the present time.

Application of Immunohistochemistry to the Genitourinary System (Prostate, Urinary Bladder, Testis, and Kidney)

Context.—The variety of morphologic patterns of different entities of the genitourinary tract can present a diagnostic dilemma for the pathologist. This is especially true in cases of mimics of cancer, a cancer of unknown primary, or poorly differentiated tumors, in which it is hard to assign histogenesis needed to plan the correct therapy for the patient. Immunohistochemistry offers a better capacity than hematoxylin-eosin staining alone to differentiate human tissue types. Also, in the past decades, several techniques had been developed to differentiate between benign and malignant processes with morphologic overlap. By using immunohistochemistry in selected cases, the rate of false-negative and false-positive diagnoses can be reduced, and some patients are afforded the opportunity to get more specific or effective therapy as a result.

Objective.—For each subgroup of genitourinary system tumors, common diagnostic problems are reviewed, and immunohistochemical markers useful in addressing these problems are discussed, along with expected patterns of immunoreactivity.

Data Sources.—The pertinent literature, with focus on immunohistochemical staining of tumors of the genitourinary tract.

Conclusions.—The addition of immunohistochemistry to the diagnostic armamentarium for genitourinary pathologic diagnosis has increased the sensitivity and specificity of diagnoses and aided in the selection of optional therapeutic regimens in selected cases.

Cystinyl aminopeptidase activity is decreased in renal cell carcinomas

The involvement of peptidases in carcinogenetic processes of several tumor types has been researched in recent years. Although kidney is one of the major tissues known to express cystinyl-aminopeptidase (CAP), little is known about its role in renal neoplasia. This study analyzes fluorimetrically membrane-bound and soluble CAP activity in the three main renal cancers: clear cell (CCRCC), papillary (PRCC), and chromophobe (ChRCC) renal cell carcinomas. Overall, a marked decrease of membrane-bound CAP activity in all the three renal cell carcinomas was detected when compared with their respective surrounding non-tumor tissues. So, the tumor vs. non-tumor CAP ratios (units of peptidase per mg of protein) was as follows: 926+/-111 vs. 3778+/-276 for CCRCCs, 737+/-181 vs. 4351+/-950 for PRCCs, and 592+/-118 vs. 4905+/-935 for ChRCCs. In contrast, the soluble fraction of this enzyme displayed minor and non-significant changes when comparing tumor and non-tumor CAP activities in the whole series. After stratification by stage and grade, CCRCCs displayed significant differences: pT3 category had significantly higher levels of membrane-bound activity than pT1, and high grade cases (G3-4) had higher soluble CAP activity than low grade ones (G1-2). These data may open additional possibilities in the study of renal cell carcinoma with regard to the prognosis of patients.

Profiling and classification tree applied to renal epithelial tumours

AIMS

Selection of the relevant combination from a growing list of candidate immunohistochemical biomarkers constitutes a real challenge. The aim was to establish the minimal subset of antibodies to achieve classification on the basis of 12 antibodies and 309 renal tumours.

METHODS AND RESULTS

Seventy-nine clear cell (CC), 88 papillary (PAP) and 50 chromophobe (CHRO) renal cell carcinomas, and 92 oncocytomas (ONCO) were immunostained for renal cell carcinoma antigen, vimentin, cytokeratin (CK) AE1-AE3, CK7, CD10, epithelial membrane antigen, alpha-methylacyl-CoA racemase (AMACR), c-kit, E-cadherin, Bcl-1, aquaporin 1 and mucin-1 and analysed by tissue microarrays. First, unsupervised hierarchical clustering performed with immunohistochemical profiles identified four main clusters-cluster 1 (CC 67%), 2 (PAP 98%), 3 (CHRO 67%) and 4 (ONCO 100%)-demonstrating the intrinsic classifying potential of immunohistochemistry. A series of classification trees was then automatically generated using Classification And Regression Tree software. The most powerful of these classification trees sequentially used AMACR, CK7 and CD10 (with 86% CC, 87% PAP, 79% CHRO and 78% ONCO correctly classified in a leave-one-out cross-validation test). The classifier was also helpful in 22/30 additional cases with equivocal features.

CONCLUSION

The classification tree method using immunohistochemical profiles can be applied successfully to construct a renal tumour classifier.

Immunohistochemical analysis of chromophobe renal cell carcinoma, renal oncocytoma, and clear cell carcinoma: an optimal and practical panel for differential diagnosis

CONTEXT

The separation of chromophobe renal cell carcinoma, oncocytoma, and clear cell renal cell carcinoma using light microscopy remains problematic in some cases.

OBJECTIVE

To determine a practical immunohistochemical panel for the differential diagnosis of chromophobe carcinoma.

DESIGN

Vimentin, glutathione S-transferase alpha (GST-alpha), CD10, CD117, cytokeratin (CK) 7, and epithelial cell adhesion molecule (EpCAM) were investigated in 22 cases of chromophobe carcinoma, 17 cases of oncocytoma, and 45 cases of clear cell carcinoma.

RESULTS

Vimentin and GST-alpha expression were exclusively observed in clear cell carcinoma. CD10 staining was more frequently detected in clear cell carcinoma (91%) than in chromophobe carcinoma (45%) and oncocytoma (29%). CD117 was strongly expressed in chromophobe carcinoma (82%) and oncocytoma (100%), whereas none of the cases of clear cell carcinomas were immunoreactive. Cytokeratin 7 was positive in 18 (86%) of 22 cases of chromophobe carcinoma, whereas all oncocytomas were negative for CK7. EpCAM protein was expressed in all 22 cases of chromophobe carcinoma in more than 90% of cells, whereas all EpCAM-positive oncocytomas (5/17; 29%) displayed positivity in single cells or small cell clusters.

CONCLUSIONS

Using the combination of 3 markers (vimentin, GST-alpha, and EpCAM), we achieved 100% sensitivity and 100% specificity for the differential diagnosis of chromophobe carcinoma, oncocytoma, and clear cell carcinoma. The pattern of "vimentin(-)/GST-alpha(-)" effectively excluded clear cell carcinoma, and homogeneous EpCAM expression confirmed the diagnosis of chromophobe carcinoma rather than oncocytoma. CD117 and CK7 were also useful markers and could be used as second-line markers for the differential diagnosis, with high specificity (100%) and high sensitivity (90% and 86%, respectively).

Diagnostic utility of S100A1 expression in renal cell neoplasms: an immunohistochemical and quantitative RT-PCR study

S100A1 is a calcium-binding protein, which has been recently found in renal cell neoplasms. We evaluated the diagnostic utility of immunohistochemical detection of S100A1 in 164 renal cell neoplasms. Forty-one clear cell, 32 papillary, and 51 chromophobe renal cell carcinomas, and 40 oncocytomas, 164 samples of normal renal parenchyma adjacent to the tumors and 13 fetal kidneys were analyzed. The levels of S100A1 mRNA detected by quantitative RT-PCR analysis of frozen tissues from seven clear cell, five papillary, and six chromophobe renal cell carcinomas, four oncocytomas, and nine samples of normal renal tissues adjacent to neoplasms were compared with the immunohistochemical detection of protein expression. Clear cell and papillary renal cell carcinomas showed positive reactions for S100A1 in 30 out of 41 tumors (73%) and in 30 out of 32 (94%) tumors, respectively. Thirty-seven renal oncocytomas out of 40 (93%) were positive for S100A1, whereas 48 of 51 (94%) chromophobe renal cell carcinomas were negative. S100A1 protein was detected in all samples of unaffected and fetal kidneys. S100A1 mRNA was detected by RT-PCR in all normal kidneys and renal cell neoplasms, although at very different levels. Statistical analyses comparing the different expression of S100A1 in clear cell and chromophobe renal cell carcinomas observed by immunohistochemical and RT-PCR methods showed significant values (P<0.001), such as when comparing by both techniques the different levels of S100A1 expression in chromophobe renal cell carcinomas and oncocytomas (P<0.001). Our study shows that S100A1 protein is expressed in oncocytomas, clear cell and papillary renal cell carcinomas but not in chromophobe renal cell carcinomas. Its immunodetection is potentially useful for the differential diagnosis between chromophobe renal cell carcinoma and oncocytoma. Further, S100A1 protein expression is constantly detected in the normal parenchyma of the adult and fetal kidney.

Morphologic and neurochemical alterations in the superior colliculus of the genetically epilepsy-prone hamster (GPG/Vall)

The GPG/Vall hamster is an animal model that exhibits seizures in response to sound stimulation. Since the superior colliculus (SC) is implicated in the neuronal network of audiogenic seizures (AGS) in other forms of AGS, this study evaluated seizure-related anatomical or neurochemical abnormalities in the SC of the GPG/Vall hamster. This involved calbindin (CB) and parvalbumin (PV) immunohistochemistry, densitometric analysis and high performance liquid chromatography in the superficial and deep layers of the SC in control and epileptic animals. Compared to control animals, a reduction in SC volume and a hypertrophy of neurons located in the deep layers of the SC were observed in the epileptic hamster. Although, analysis of CB-immunohistochemistry in the superficial layers did not show differences between groups, analysis of PV-immunostaining in the deep SC revealed an increase in the mean gray level within immunostained neurons as well as a decreased immunostained neuropil in the GPG/Vall hamster as compared to control animals. These alterations were accompanied by a decrease in the levels of GABA and increased levels of taurine in the epileptic animal. These data indicate that the deep SC of the GPG/Vall hamster is structurally abnormal; suggesting its involvement in the neuronal network for AGS.

Chromosomal gains in the sarcomatoid transformation of chromophobe renal cell carcinoma

The hallmark of chromophobe renal cell carcinoma is multiple chromosomal losses from among chromosomes 1, 2, 6, 10 and 17. Chromophobe renal cell carcinoma with distant metastases or sarcomatoid transformation are uncommon and little is known about their chromosomal abnormalities. We collected six sarcomatoid chromophobe renal cell carcinomas and three primary chromophobe renal cell carcinomas with distant metastases. A cytogenetic analysis by fluorescent in situ hybridization on paraffin-embedded tissue was performed using centromeric probes for chromosomes 1, 2, 6, 10 and 17. We found more than one signal in four of six (66%) sarcomatoid chromophobe renal cell carcinomas, in both sarcomatoid and adjacent epithelial components. Both primary chromophobe renal cell carcinomas and matched metastases showed single signals for all chromosomes studied in two cases and no abnormalities in the remaining case. We concluded that: (1) both epithelial and sarcomatoid components of sarcomatoid chromophobe renal cell carcinoma show different genetic abnormalities from those characteristic of chromophobe renal cell carcinoma; (2) sarcomatoid chromophobe renal cell carcinomas frequently have multiple gains (polysomy) of chromosomes 1, 2, 6, 10 and 17; (3) distant metastases show the same genetic patterns, usually chromosomal losses (monosomy), found in the primary tumors.

Oncocytic papillary renal cell carcinoma: a clinicopathologic, immunohistochemical, ultrastructural, and interphase cytogenetic study of 12 cases

Papillary renal cell carcinoma (RCC) is subclassified in type 1 displaying cells with scanty pale cytoplasm arranged in a single layer and in type 2 showing pseudostratified cells with eosinophilic cytoplasm. However, the existence of more variants of papillary RCC may be inferred by the recognition of few cases with different morphological features. We report the clinicopathologic, immunohistochemical, ultrastructural, and interphase cytogenetic features of 12 papillary RCC composed by oncocytes. Ten patients were males and their median age was 67 years. The tumors were well demarcated and their median diameter was 7.1 cm. Solid oncocytoma-like areas occurred in 11 cases. The cytoplasm of the neoplastic cells was filled by mitochondria with lamellar cristae. All cases were positive for the antimitochondrial antigen and racemase and showed variable immunoreactivity for cytokeratins (AE1/AE3, CK8-18, CK7, CK19), EMA, CD10, vimentin, and parvalbumin. MIB1 was detected in 0 to 6 cells per 1 high-power field. Fluorescent in situ hybridization analysis on formalin-fixed paraffin-embedded tissue showed three or more signals for chromosome 7 and 17 (for both > or =30% of nuclei in 7 of 12 neoplasms). In males, signals of chromosome Y were absent in more than 80% of the neoplastic nuclei. One patient died of metastases. Interphase cytogenetic analysis by fluorescent in situ hybridization can be a diagnostic tool in cases mimicking an oncocytoma.

An immunohistochemical approach to the differential diagnosis of renal tumors

Renal neoplasms comprise several distinct clinicopathologic entities with potential prognostic and the rapeutic differences. Although careful morphologic examination using sections stained with hematoxylin and eosin will allow for the correct diagnosis in the majority of cases, there is sufficient overlap between several entities such that ancillary techniques may be necessary to arrive at the correct diagnosis. In routine diagnostic surgical pathology practice of renal tumors, immunohistochemistry is the foremost ancillary technique. Using an approach based on common histologic patterns (tumors with clear cytoplasm, granular cytoplasm, tubulopapillary architecture, spindle cell morphology, small round-cell morphology, and infiltrating poorly differentiated carcinoma), we will discuss the utility of immunohistochemistry in the differential diagnosis of renal neoplasms. In recent years, needle biopsies from renal masses are being increasingly performed. In these small biopsies, the entire range of cytoarchitectural features that are generally necessary to make a diagnosis may not be fully appreciated. Immunohistochemistry may be helpful in this setting to narrow the differential diagnosis or to arrive at a definitive diagnosis. Finally, the use of immunohistochemistry for the confirmation of metastatic renal cell carcinoma presenting at distant sites will be discussed. Panels of immunohistochemical stains are proposed for different settings, including renal cell carcinoma (RCC) marker, CD10, and vimentin to suggest renal origin of a metastatic tumor, and markers to aid in subclassification of RCC, including parvalbumin and c-kit for chromophobe RCC, and cytokeratin 7 and alpha-methyl-acyl-CoA racemase for papillary RCC.

Natural history of the Nihon (Bhd gene mutant) rat, a novel model for human Birt–Hogg–Dubé syndrome

In the Nihon rat, an established model of hereditary renal cell carcinoma (RCC), the propensity for tumor development, is inherited as an autosomal dominant trait due to a single germline nucleotide insertion mutation in the rat Bhd ortholog. The Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant disease characterized by fibrofolliculoma, pulmonary cysts, spontaneous pneumothorax, and renal neoplasm. The renal lesions of the Nihon rat are characterized, and extrarenal lesions are also described in this work. The earliest lesion of the RCC was identified as an altered tubule at as early as 3 weeks of age and rapidly progressed through adenoma to carcinoma with the primary cell type being clear/acidophilic where some similarities were evident to RCCs in BHD syndrome. The Nihon rats demonstrate a heterotopic ossification within RCCs and three extrarenal lesions, clear cell hyperplasia/adenoma of the endometrium, clear cell change of the epithelium of striated portions of salivary glands, and cardiac rhabdomyomatosis. This rat model of hereditary RCC provides a useful tool for analyzing the series of events leading to renal tumorigenesis and for studying BHD gene functions.

Aplicación clínica de las actuales clasificaciones del cáncer renal

The purpose of classifying neoplasias is to recognize groups with similar progress and prognosis and, if possible, receiving the same treatment. This is why those classifications are systematically being submitted to review and improvement through the new technologies. Differentiation of various entities in renal cancer has been comparatively fast, as the new genetic and molecular discoveries have confirmed the morphologic criteria of the different cell types, thus making it possible to open new therapeutic pathways. Using the current WHO classification we recognize subtypes with excellent prognosis (Multilocular cystic renal carcinoma, Type I renal papillary carcinoma, Tubular and fusocellular mucinous carcinoma), other very aggressive ones (Bellini's collecting duct carcinoma, Medullary carcinoma), and also that the sarcomatoid transformation, even in small areas, impacts the prognosis negatively. Childhood-characteristic renal carcinomas associated with chromosome translocations have been recognized (genetic fusion TFE3 or TFEB), as well as the family forms of renal carcinoma. Regarding the UICC (International Union Against Cancer) classification, there are a series of aspects under argument (size, venous invasion, microvascular invasion, invasion of the adipous tissue of the renal sinus) that shall be discussed too, since it is possible that some modifications of the TNM might occur in the near future.

Morphologic and neurochemical abnormalities in the auditory brainstem of the genetically epilepsy-prone hamster (GPG/Vall)

PURPOSE

This study was performed to evaluate whether audiogenic seizures, in a strain of genetically epilepsy-prone hamsters (GPG/Vall), might be associated with morphologic alterations in the cochlea and auditory brainstem. In addition, we used parvalbumin as a marker of neurons with high levels of activity to examine changes within neurons.

METHODS

Cochlear histology as well as parvalbumin immunohistochemistry were performed to assess possible abnormalities in the GPG/Vall hamster. Densitometry also was used to quantify levels of parvalbumin immunostaining within neurons and fibers in auditory nuclei.

RESULTS

In the present study, missing outer hair cells and spiral ganglion cells were observed in the GPG/Vall hamster. In addition, an increase was noted in the size of spiral ganglion cells as well as a decrease in the volume and cell size of the cochlear nucleus (CN), the superior olivary complex nuclei (SOC), and the nuclei of the lateral lemniscus (LL) and the inferior colliculus (IC). These alterations were accompanied by an increase in levels of parvalbumin immunostaining within CN, SOC, and LL neurons, as well as within parvalbumin-immunostained fibers in the CN and IC.

CONCLUSIONS

These data are consistent with a cascade of atrophic changes starting in the cochlea and extending along the auditory brainstem in an animal model of inherited epilepsy. Our data also show an upregulation in parvalbumin immunostaining in the neuropil of the IC that may reflect a protective mechanism to prevent cell death in the afferent sources to this nucleus.

The usefulness of immunohistochemical markers in the differential diagnosis of renal neoplasms

Histologic subtyping of RCC has been shown to be of prognostic value; therefore, it is important to classify malignant epithelial tumors of the kidney correctly and also to differentiate them from benign ones. Overlapping morphologic features of renal tumors sometimes make histologic subtyping difficult. The accurate diagnosis and classification of RCC are based on cytoarchitectural features and require correlation with immunophenotype and cytogenetic characteristics. RCC Ma and CD10, two markers with relative renal specificity, have been used to confirm a diagnosis of suspected RCC and can facilitate the accurate diagnosis of metastatic RCC, in particular, in FNA. Although CCRCC and PRCC share most immunomarkers, CK7 and AMACR expression can be helpful in the differential diagnosis of challenging histologic variants of the two. In addition, E-cadherin aids in the distinction between types 1 and 2 PRCC. Useful markers in the differential diagnosis between ChRCC and CCRCCare CK7, RCC Ma, CD10, VIM, CD117, parvalbumin, and E-cadherin. We propose CK7/CK20/CD15 as a useful primary immunopanel to differentiate ChRCC from ONC reliably.