Role of immunohistochemistry in diagnosing renal neoplasms: when is it really useful?

Atypical Presentation of Rapidly Progressive Cutaneous Metastases of Clear Cell Renal Carcinoma: A Case Report

Cutaneous metastases from clear cell renal carcinoma (ccRC) are uncommon and often indicate a poor prognosis. These metastases typically occur on the scalp, face, and trunk, and they can be difficult to diagnose due to their resemblance to benign dermatological tumors. We report the case of a 56-year-old patient with a history of ccRC (TNM stage 4) who was referred to our dermatology department with two rapidly enlarging, painful lesions on the left jawline and scalp, which had developed one month and one week earlier, respectively. On examination, the lesions appeared as well-defined, round to oval plaques with a central ulceration and a peripheral red rim, suggestive of an inflammatory appearance. Dermoscopic examination revealed a structureless pink to orange pattern, atypical central vessels, and irregular linear vessels in a corona-like arrangement. Despite the patient's stable oncological treatment for six months, pain management had recently included paracetamol, tramadol, and NSAIDs. The primary presumptive diagnosis was of cutaneous metastasis, considering the patient's history of metastatic ccRC. However, given the recent initiation of new pharmacological agents, the rapid progression of the cutaneous lesions, and their clinical presentation, alternative differential diagnoses were considered, including drug-induced reactions such as erythema multiforme or fixed drug eruption. A biopsy of the facial lesion revealed immunohistochemical positivity for CD10, CAIX, and PAX8, confirming the diagnosis of metastatic ccRC with sarcomatoid differentiation. Unfortunately, despite continued targeted therapies and palliative care, the patient's condition deteriorated rapidly, leading to death two months later. This case highlights the potential for extremely rapidly evolving cutaneous metastases from ccRC and their capacity to occasionally mimic atypical drug eruptions. Additionally, it reaffirms the poor prognosis of such metastases, as evidenced by the patient's death within two months.

Diagnostic Biomarkers in Renal Cell Tumors According to the Latest WHO Classification: A Focus on Selected New Entities

The fifth edition of the World Health Organization (WHO) classification for urogenital tumors, released in 2022, introduces some novelties in the chapter on renal epithelial tumors compared to the previous 2016 classification. Significant changes include the recognition of new disease entities and adjustments in the nomenclature for certain pathologies. Notably, each tumor entity now includes minimum essential and desirable criteria for reliable diagnosis. This classification highlights the importance of biological and molecular characterization alongside traditional cytological and architectural features. In this view, immunophenotyping through immunohistochemistry (IHC) plays a crucial role in bridging morphology and genetics. This article aims to present and discuss the role of key immunohistochemical markers that support the diagnosis of new entities recognized in the WHO classification, focusing on critical topics associated with single markers, in the context of specific tumors, such as the clear cell capillary renal cell tumor (CCPRCT), eosinophilic solid and cystic renal cell carcinoma (ESC-RCC), and so-called "other oncocytic tumors", namely the eosinophilic vacuolated tumor (EVT) and low-grade oncocytic tumor (LOT). Their distinctive characteristics and immunophenotypic profiles, along with insights regarding diagnostic challenges and the differential diagnosis of these tumors, are provided. This state-of-the-art review offers valuable insights in biomarkers associated with novel renal tumors, as well as a tool to implement diagnostic strategies in routine practice.

Renal cell carcinoma metastasis without a primary: A case report

In Australia, approximately 3 % of all cancers diagnosed each year are renal cancers. Renal Cell Carcinoma (RCC) represents 90 % of all primary renal malignancies. RCC are slow growing and often asymptomatic, thus are often found incidentally. Here we present the case of a 76-year-old male who was found to have a metastatic RCC in a para-aortic lymph node with no primary lesion. He underwent a retroperitoneal lymphadenectomy and 15 months after the surgery, has had no signs of primary tumours or metastasis. This case reports on a rare instance of metastatic RCC without an identified primary renal malignancy.

Biomolecular condensates in kidney physiology and disease

The regulation and preservation of distinct intracellular and extracellular solute microenvironments is crucial for the maintenance of cellular homeostasis. In mammals, the kidneys control bodily salt and water homeostasis. Specifically, the urine-concentrating mechanism within the renal medulla causes fluctuations in extracellular osmolarity, which enables cells of the kidney to either conserve or eliminate water and electrolytes, depending on the balance between intake and loss. However, relatively little is known about the subcellular and molecular changes caused by such osmotic stresses. Advances have shown that many cells, including those of the kidney, rapidly (within seconds) and reversibly (within minutes) assemble membraneless, nano-to-microscale subcellular assemblies termed biomolecular condensates via the biophysical process of hyperosmotic phase separation (HOPS). Mechanistically, osmotic cell compression mediates changes in intracellular hydration, concentration and molecular crowding, rendering HOPS one of many related phase-separation phenomena. Osmotic stress causes numerous homo-multimeric proteins to condense, thereby affecting gene expression and cell survival. HOPS rapidly regulates specific cellular biochemical processes before appropriate protective or corrective action by broader stress response mechanisms can be initiated. Here, we broadly survey emerging evidence for, and the impact of, biomolecular condensates in nephrology, where initial concentration buffering by HOPS and its subsequent cellular escalation mechanisms are expected to have important implications for kidney physiology and disease.

Cadherin-16 (CDH16) immunohistochemistry: a useful diagnostic tool for renal cell carcinoma and papillary carcinomas of the thyroid

Cadherin-16 (CDH16) plays a role in the embryonal development in kidney and thyroid. Downregulation of CDH16 RNA was found in papillary carcinomas of the thyroid. To determine the expression of CDH16 in tumors and to assess the diagnostic utility a tissue microarray containing 15,584 samples from 152 different tumor types as well as 608 samples of 76 different normal tissue types was analyzed. A membranous CDH16 immunostaining was predominantly seen in thyroid, kidney, cauda epididymis, and mesonephric remnants. In the thyroid, CDH16 staining was seen in 100% of normal samples, 86% of follicular adenomas, 60% of follicular carcinomas, but only 7% of papillary carcinomas (p < 0.0001). CDH16 positivity was frequent in nephrogenic adenomas (100%), oncocytomas (98%), chromophobe (97%), clear cell (85%), and papillary (76%) renal cell carcinomas (RCCs), various subtypes of carcinoma of the ovary (16-56%), various subtyped of carcinomas of the uterus (18-40%), as well as in various subtypes of neuroendocrine neoplasms (4-26%). Nineteen further tumor entities showed a weak to moderate CDH16 staining in up to 8% of cases. Our data suggest CDH16 as a potential diagnostic marker-as a part of a panel-for the identification of papillary carcinomas of the thyroid, nephrogenic adenomas, and the distinction of renal cell tumors from other neoplasms.

Metastasis of Renal Cell Carcinoma to the Mandible

Renal cell carcinoma (RCC) is the most common tumor of the kidney. Although RCC often metastasizes to other organs, metastasis to the head and neck region is rare, and metastasis to the mandible is very unusual. Given the fact that metastasis of primary neoplasms is not always predictable, it is essential to rule out metastatic carcinoma in jaw lesions. We herein report a rare presentation of metastasis of RCC to the mandible, in which the metastatic lesion in the oral cavity was found first, followed by the primary lesion, in a 22-year-old girl who suffered from pain in the left temporomandibular joint on mouth opening and hypoesthesia of the left chin, left lower lip, and left lower gum.

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.

Isolated late intradural cauda equina metastasis of renal cell carcinoma

Background:

The cauda equina (CE) is the most common site for intradural extramedullary metastasis from systemic malignancies such as lung, breast, and thyroid carcinomas. However, renal cell carcinomas (RCC), with their high metastatic potential, are rarely responsible for CE metastatic lesions. Here, we report an intradural cauda equina mass, as the first and only site of metastasis of a renal cell carcinoma.

Case Description:

A 55-year-old female had undergone a left nephrectomy for renal cell carcinoma 8 years ago. She now presented with a unifocal renal cell metastasis to the CE. As such metastases are rare, establishing the correct pathological diagnosis proved to be a challenge.

Conclusion:

The cauda equina was the first and only site of an 8-year-delayed metastasis attributed to a renal cell carcinoma.

Diagnostic accuracy of core biopsies of renal masses: Experience in a real-life setting from a tertiary center

OBJECTIVE

To document and analyze diagnostic accuracy of renal core biopsy (RCB), its diagnostic correlation with resection specimens, and to question the need for immunohistochemistry (IHC) in the preoperative diagnosis of renal masses.

MATERIAL AND METHOD

RCBs performed at a reference center between 2007 and 2017 were included. Pathological, clinical, and radiological data were obtained from medical records.

RESULTS

Among 302 biopsies included in this study, 274 (90.7%) were diagnostic. Two hundred sixty-six were neoplastic and 179 were of primary renal origin. The most common secondary neoplasms were hematolymphoid (n = 35) and metastatic (n = 17). Sixty-nine tumors were classified as small renal masses (SRMs) (≤4 cm in diameter) and 53 of them were malignant. Nephrectomy was performed in 58 patients. Overall diagnostic accuracy between resections and RCBs was 88.7%. IHC was performed in 160 (53%) cases. In 15 of those, a definite diagnosis could not be rendered. Renal cell origin and subtype were determined by histomorphology alone in 81 and 75 cases, respectively. Sixty primary neoplasms of renal cell origin required IHC for diagnosis.

CONCLUSION

RCB is a safe and highly accurate method for the diagnosis of both primary and secondary renal neoplasms. IHC is mostly required for the diagnosis of secondary tumors. Histomorphology is still the primary diagnostic tool, highly dependent on the experience of the surgical pathologist.

Renal Crest Proliferative Lesions in Cats with Chronic Kidney Disease

In a histopathological study of the renal crest (RC) of kidneys of cats with chronic kidney disease (CKD), 58/90 (64%) had epithelial proliferation. Of these, 33 cats had hyperplasia of the collecting duct (CD) epithelium (CDH) alone, eight had hyperplasia of the urothelium covering the RC (RCUH), of which one had concurrent abaxial renal pelvic urothelial hyperplasia (UH), and eight had both CDH and RCUH. CDH or RCUH were present in five cats with marked dysplasia of the CD epithelium (CDD) and four cats with invasive carcinomas, which also had epithelial dysplasia. All nine cats with marked dysplasia or neoplasia of the RC also had substantially altered RC contours due to focal haemorrhage, papillary necrosis or fibrosis. Three of the carcinomas had a strong desmoplastic response. In control cats, both urothelial (RC and renal pelvis) and tubular (CD and distal tubular) cells were immunopositive for cytokeratin (CK; AE1/AE3), tubular epithelial cells were positive for vimentin (Vim) and aquaporin 2 (Aq2), while urothelial cells were positive for p63. PAX8 immunolabelling was difficult to validate. CD and UH labelling was similar to control tissue. While urothelial dysplasia had the same immunolabelling pattern as UH and control tissue, CDD was generally immunonegative for Aq2. As immunolabelling of the four carcinomas did not distinguish between tubular and urothelial origin, with three positive for both Vim and p63, all were broadly designated as RC carcinomas. Overall, proliferative epithelial lesions are common in cats with CKD and form a continuum from simple hyperplasia to neoplasia of the urothelium or CD of the RC.

Absolute quantitative proteomics using the total protein approach to identify novel clinical immunohistochemical markers in renal neoplasms

BACKGROUND

Renal neoplasms encompass a variety of malignant and benign tumors, including many with shared characteristics. The diagnosis of these renal neoplasms remains challenging with currently available tools. In this work, we demonstrate the total protein approach (TPA) based on high-resolution mass spectrometry (MS) as a tool to improve the accuracy of renal neoplasm diagnosis.

METHODS

Frozen tissue biopsies of human renal tissues [clear cell renal cell carcinoma (n = 7), papillary renal cell carcinoma (n = 5), chromophobe renal cell carcinoma (n = 5), and renal oncocytoma (n = 5)] were collected for proteome analysis. Normal adjacent renal tissue (NAT, n = 5) was used as a control. Proteins were extracted and digested using trypsin, and the digested proteomes were analyzed by label-free high-resolution MS (nanoLC-ESI-HR-MS/MS). Quantitative analysis was performed by comparison between protein abundances of tumors and NAT specimens, and the label-free and standard-free TPA was used to obtain absolute protein concentrations.

RESULTS

A total of 205 differentially expressed proteins with the potential to distinguish the renal neoplasms were found. Of these proteins, a TPA-based panel of 24, including known and new biomarkers, was selected as the best candidates to differentiate the neoplasms. As proof of concept, the diagnostic potential of PLIN2, TUBB3, LAMP1, and HK1 was validated using semi-quantitative immunohistochemistry with a total of 128 samples assessed on tissue micro-arrays.

CONCLUSIONS

We demonstrate the utility of combining high-resolution MS and the TPA as potential new diagnostic tool in the pathology of renal neoplasms. A similar TPA approach may be implemented in any cancer study with solid biopsies.

Reconnaissance of tumor immune microenvironment spatial heterogeneity in metastatic renal cell carcinoma and correlation with immunotherapy response

A clearer understanding of the tumor immune microenvironment (TIME) in metastatic clear cell renal cell carcinoma (ccRCC) may help to inform precision treatment strategies. We sought to identify clinically meaningful TIME signatures in ccRCC. We studied tumors from 39 patients with metastatic ccRCC using quantitative multiplexed immunofluorescence and relevant immune marker panels. Cell densities were analyzed in three regions of interest (ROIs): tumor core, tumor-stroma interface and stroma. Patients were stratified into low- and high-marker density groups using median values as thresholds. Log-rank and Cox regression analyses while controlling for clinical variables were used to compare survival outcomes to patterns of immune cell distributions. There were significant associations with increased macrophage (CD68⁺ CD163⁺ CD206⁺ ) density and poor outcomes across multiple ROIs in primary and metastatic tumors. In primary tumors, T-bet⁺ T helper type 1 (Th1) cell density was highest at the tumor-stromal interface (P = 0·0021), and increased co-expression of CD3 and T-bet was associated with improved overall survival (P = 0·015) and survival after immunotherapy (P = 0·014). In metastatic tumor samples, decreased forkhead box protein 3 (FoxP3)⁺ T regulatory cell density correlated with improved survival after immunotherapy (P = 0·016). Increased macrophage markers and decreased Th1 T cell markers within the TIME correlated with poor overall survival and treatment outcomes. Immune markers such as FoxP3 showed consistent levels across the TIME, whereas others, such as T-bet, demonstrated significant variance across the distinct ROIs. These findings suggest that TIME profiling outside the tumor core may identify clinically relevant associations for patients with metastatic ccRCC.

Accuracy of Subclassification and Grading of Renal Tumors on Fine Needle Aspiration Cytology Alone

BACKGROUND

Fine needle aspiration (FNA) of renal masses can distinguish between benign and malignant neoplasms in 73-94% of cases. Previous studies suggested the correct subclassification of renal cell carcinomas (RCCs) by cytomorphology can be achieved in up to 80% of cases. However, as RCCs become increasingly subclassified by molecular signatures, correct subclassification based on cytology alone is increasingly difficult.

DESIGN

Two FNA passes (2 stained with Diff-Quik® and 2 with the Papanicolaou method) were performed on all fresh nephrectomy specimens for a 1-year period. There were 30 cases in this study, with 29 primary renal tumors and 1 case of metastatic lung adenocarcinoma. Each case was assigned a random number and came with 2 slides (1 from each staining method). Eight cytopathologists were asked to provide a diagnosis and the World Health Organization/International Society of Urological Pathology (WHO/ISUP) grading if applicable. Fleiss' Kappa and Cohen's Kappa equations were used to look at inter-rater variability.

RESULTS

When compared to the surgical pathology diagnosis, the average percent correct diagnosis for all cytopathologist was 35%. Chromophobe RCCs had the best average percent accuracy at 72% followed by clearcell RCC at 48%. Average accuracy for grading RCCs was 40%. Inter-rater variability among the cytopathologists for all RCC diagnoses was fair with a Fleiss' Kappa coefficient of 0.28. For the WHO/ISUP grade, the weighted coefficient for each pathologist ranged from 0.11 to 0.45, ranging from fair to moderate, respectively.

CONCLUSIONS

Renal tumors are difficult to classify on cytopathology alone. Core needle biopsy and ancillary studies are necessary if diagnosis will change management.

Clear-Cell Adenocarcinoma of the Gallbladder with Alpha-Fetoprotein Production: A Case Report and Review of the Literature

Gallbladder tumors are the fifth most common cancers of the gastrointestinal tract with poor prognosis and low survival. The most common type is adenocarcinoma of which the clear cell type is an unusual histologic variant with alpha-fetoprotein (AFP)-producing gallbladder carcinoma, reported extremely rarely, which makes the index case an uncommon entity. AFP secretion by gallbladder carcinomas may occur given the similar embryological origin of liver and gallbladder. Herein we report a case of an incidental carcinoma of the gallbladder in a 60-year-old woman with an elevated serum AFP concentration at presentation, who underwent cholecystectomy for cholelithiasis and was rendered the diagnosis of AFP-producing clear cell carcinoma of the gallbladder through histopathology and immunohistochemistry. Her postoperative laboratory tests showed a decline in AFP levels to normal respectively. The clinical and pathologic importance of AFP production by clear-cell adenocarcinoma of the gallbladder (CCG) has thus far remained completely obscure. However, we must recognize the entity of this tumor because accurate and early diagnosis of CCG is imperative to avoid misdiagnosis as possible secondary metastasis and consequent delay in appropriate surgical intervention. Relevant medical history of a patient, various imaging studies, foci of classical adenocarcinoma within the tumor, and an efficient immunohistochemical panel can be informative and assist in arriving at an accurate diagnosis.

Facial Cutaneous Metastasis in Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a common genitourinary malignancy of increasing incidence and significant mortality rate. Skin metastases of RCC are considered a rare phenomenon of unfavorable outcomes. We present a 75-year-old male patient who developed a rapidly evolving lesion on his left cheek four years after undergoing a right radical nephrectomy for non-metastatic RCC. Immunohistochemistry of the skin lesion was diagnostic for cutaneous metastasis of renal clear cell carcinoma, which eventually led to the detection of internal malignancy recurrence by positron emission tomography. A new facial skin lesion may unmask the underlying recurrence of RCC.

Eosinophilic Renal Cell Tumors With a TSC and MTOR Gene Mutations Are Morphologically and Immunohistochemically Heterogenous: Clinicopathologic and Molecular Study

Eosinophilic renal neoplasms have a wide spectrum of histologic presentations, and several studies have demonstrated a subtype of renal cell carcinomas (RCCs) associated with the tuberous sclerosis complex (TSC)/mammalian target of rapamycin pathway. A review of our institutional archives led to the identification of 18 cases of renal eosinophilic tumors with unusual morphology. Immunohistochemical analysis demonstrated that these could be separated into 3 groups: group 1 had solid architecture and morphology similar to chromophobe RCC but was negative for CK20 and vimentin, and had weak focal staining for CK7 and P504S; group 2 had solid architecture and morphology similar to either renal oncocytoma or chromophobe RCC, eosinophilic variant and had diffuse staining of CK7 and P504S, absent to weak staining of CK20, and negative staining for vimentin; and group 3 had solid, cystic and papillary architecture and was negative for CK7, except for 1 case, along with moderate to strong staining of CK20, P504S, and vimentin. The cases were then sent for next-generation sequencing to determine whether molecular pathogenic variants were present. In group 1, all 3 cases had mutations in TSC2. In group 2, pathogenic variants were identified in 3 genes: TSC1, TSC2, and MTOR. In group 3, genetic alterations and pathogenic variants were identified in TSC1 and TSC2. Our results support TSC/MTOR-associated neoplasms as a distinct group that exhibits heterogenous morphology and immunohistochemical staining.

CD57 as a routine neuroendocrine marker for liver metastasis

Background

The characterization of hepatic metastases as having neuroendocrine origins is essential and the main markers currently used are chromogranin A (CgA) and synaptophysin (Syn). However, these markers may exhibit certain limitations, and the use of CD56 and CD57 can also be considered, although, due to low specificity, their use is discouraged.

Aim

This study sought to compare the immunohistochemical expression of these markers in hepatic metastases of neuroendocrine neoplasms (NEN).

Materials and Methods

Eighteen samples, were used for immunohistochemical staining with CgA, Syn, CD56, and CD57 antibodies. The immunostaining reactions were compared according to its intensity (I), the percentage of labeled cells (P), and a final score (I × P). Statistical agreement between the markers was also evaluated.

Results

CD57 was expressed in the highest number of cases and also showed the most intense expression. CgA showed the highest number of cases with more than 80% positively stained area (72.2%), followed by CD57 (61.1%). The highest average score (I × P) was obtained for CD57 (9.1 ± 4.1). The best indices of agreement were between CgA and CD57 with respect to positivity (P = 0.021) and score (P = 0.014). According to the primary site, stomach/duodenum, lungs, and undetermined subgroups showed the highest average scores for CD57, followed by CgA. For the small bowel subgroup, the highest average score was obtained for CgA, followed by CD57.

Conclusion

Our results highlight the importance of CD57 in the evaluation of hepatic metastases of NEN and indicate that this marker should be included with CgA and Syn in routine diagnostic panels.

Can renalase be a novel candidate biomarker for distinguishing renal tumors?

Renalase (RNLS) is synthesized mainly in renal tissues. The function of RNLS in cancerous renal tissues has not been investigated. We investigated the synthesis of RNLS in chromophobe renal cell carcinoma, papillary renal cell carcinoma and clear cell renal cell carcinoma with Fuhrman grades (FG): FG1, nucleoli are absent or inconspicuous and basophilic; FG2, nucleoli are conspicuous and eosinophilic and visible but not prominent; FG3, nucleoli are conspicuous and eosinophilic; FG4, extreme nuclear pleomorphism, multinucleate giant cells, and/or rhabdoid and/or sarcomatoid differentiation. We used 90 tissue samples including 15 healthy controls, 15 chromophobe renal cell carcinoma tissues and 10 papillary renal cell carcinoma renal tissues: 12 FG1, 14 FG 2, 14 FG 3 and 10 FG4. RNLS in the tissue samples was measured using enzyme linked immunosorbent assay and immunostaining of RNLS in these tissues. RNLS was significantly greater in the chromophobe renal cell carcinoma and papillary renal cell carcinoma tissues than the control. The least amount of RNLS was found in the renal tissues of clear cell renal cell carcinoma FG1; the amount of RNLS increased as the FG grades increased. Because RNLS increased significantly in renal tissues due to cancer, except for clear cell renal cell carcinoma FG1, RNLS may be useful biomarker for distinguishing grades of renal cancer. Because RNLS increases cell survival, anti-RNLS preparations may be useful for treating cancer in the future.

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.

Differentiation of renal cell tumors with morphological cocktails using a minimal panel of immunohistochemical markers

Context:

Morphological cocktails in renal cell carcinoma (RCC).

Aims:

Minimal immunohistochemistry (IHC) panel to resolve the diagnosis of renal cell cacinoma (RCC) with morphological overlaps.

Settings and Design:

RCC is the most common malignancy in kidney accounting for 90% of all kidney cancers. Clear cell RCC is the most common histological type followed by papillary RCC. However, many of the RCCs show morphological cocktails which may pose diagnostic difficulties in small biopsies and even in the resection specimens. Accurate diagnosis has both prognostic and therapeutic implications; hence, correct differentiation is necessary.

Subjects and Methods:

This retrospective study includes all renal cell tumors diagnosed on core biopsies, radical and partial nephrectomies between January 2015 and September 2017 were studied. The demographic, clinical, and gross findings were noted. The cases that had morphological overlap among the subtypes were subjected to a panel of IHC markers, including CD10, CK7, alpha-methyl acyl-coenzymeA racemase (AMACR), and CD117.

Results:

There were 128 RCC in the study period, and morphological overlap was seen in 36 (27.9%) specimens including 13 core biopsies, 16 radical, and 7 partial nephrectomies. IHC resolved 35/36 (97.2%) cases rendering a diagnosis of clear cell (11), papillary (15), chromophobe (4), and oncocytoma (5). However, in one case where the provisional diagnosis was oncocytic tumor, all IHC markers were negative rendering IHC noncontributory.

Conclusions:

Difficulty in diagnosis was encountered in many core biopsies, resection specimens which when subjected to IHC panel of CD10, CK7, AMACR, and CD117 helped in resolving the diagnosis of subtypes of RCC.

Metastatic Tumors of the Oro-Facial Tissues: Clear Cell Renal Cell Carcinoma. A Clinico-Pathological and Immunohistochemical Study of Seven Cases

Metastases to orofacial tissues are infrequent, their incidence being 1-8% of malignant oral tumors, sometimes manifesting as the first clinical sign of an occult cancer. Renal cell carcinoma (RCC) is the second most common metastatic carcinoma to the oro-facial tissues, involving the jawbones, gingiva, oral mucosa, tongue or salivary glands. Also, RCC frequently displays a prominent clear cell component, which may predominate in the clear cell renal cell carcinoma subtype (CCRCC) and histologically mimic many other clear cell tumors, both benign and malignant, which can be epithelial (from keratinizing epithelia, cutaneous adnexa, salivary glands and odontogenic epithelium), melanocytic or mesenchymal in origin. In view of the necessity for prompt and accurate diagnosis of such unusual neoplasms, we report on the salient clinico-pathological features of 7 CCRCC metastatic to the oro-facial tissues, and highlight their immunohistochemical profile, to more accurately discriminate this neoplasm from other tumors of the oral cavity with a prominent clear cell component.

High-Dose Vitamin C Preadministration Reduces Vancomycin-Associated Nephrotoxicity in Mice

Vancomycin is recommended for treating severe infections caused by Gram-positive cocci, including methicillin-resistant Staphylococcus aureus. However, renal damage often occurs as a side effect because vancomycin is mainly excreted via the kidneys. The mechanism of vancomycin-associated nephrotoxicity is thought to involve the elevation of oxidative stress in the kidneys. Vitamin C (VC) has strong antioxidant properties; therefore, we evaluated the effect of high-dose VC preadministration on vancomycin-associated nephrotoxicity. Vancomycin was intraperitoneally injected into mice once daily for 7 d. Additionally, high-dose VC was intraperitoneally injected into mice at 30 min before vancomycin administration for 7 d. The plasma creatinine and urea nitrogen levels were increased by vancomycin treatment; however, high-dose VC preadministration suppressed the increase in these levels. Histological examination also revealed that high-dose VC preadministration reduced the characteristics of vancomycin-associated nephrotoxicity, such as dilated renal tubules with casts, the dilation of renal proximal tubules, and tubular epithelial desquamation. Furthermore, high-dose VC preadministration reduced the appearance of apoptotic cells presumably derived from the epithelial cells in the dilated proximal tubules. Thus, intraperitoneally injected high-dose VC preadministration reduced vancomycin-associated nephrotoxicity in mice. These novel findings may indicate that vancomycin-associated nephrotoxicity in humans may be reduced by high-dose VC preadministration.

Recent advances in the biology of tumour hypoxia with relevance to diagnostic practice and tissue-based research

In this review article, we examine the importance of low levels of oxygen (hypoxia) in cancer biology. We provide a brief description of how mammalian cells sense oxygen. The hypoxia-inducible factor (HIF) pathway is currently the best characterised oxygen-sensing system, but recent work has revealed that mammals also use an oxygen-sensing system found in plants to regulate the abundance of some proteins and peptides with an amino-terminal cysteine residue. We discuss how the HIF pathway is affected during the growth of solid tumours, which develop in microenvironments with gradients of oxygen availability. We then introduce the concept of 'pseudohypoxia', a state of constitutive, oxygen-independent HIF system activation that occurs due to oncogenic stimulation in a number of specific tumour types that are of immediate relevance to diagnostic histopathologists. We provide an overview of the different methods of quantifying tumour hypoxia, emphasising the importance of pre-analytic factors in interpreting the results of tissue-based studies. Finally, we review recent approaches to targeting hypoxia/HIF system activation for therapeutic benefit, the application of which may require knowledge of which hypoxia signalling components are being utilised by a given tumour. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Papillary renal cell carcinoma: what is missing in research? A case report and a review of literature

The incidence of renal cell carcinomas in adults ranges has been increasing over the past decades in both men and women. Once the incidence was 2.9%, now is reported to have increased to 3%–5% with male predominance according to the most recent reports of cancer statistics. The disease typically describes a group of different histopathological subtypes; the most common is clear cell carcinoma which accounts for 70%–80% of the diagnosed cases, while papillary renal cell carcinoma and chromophobe types represent 20% and 5%, respectively. In 1996, the renal cell carcinomas Heidelberg classification was introduced by Delahunt et al. It divides renal cell tumors into benign and malignant parenchymal neoplasms, excluding Wilm’s tumor and secondary metastases and limiting each subcategory to the most commonly documented genetic abnormalities, if applicable. In this report, we discuss a case of metastatic type I papillary renal cell carcinoma treated with the anti-vascular endothelial growth factor receptor sunitinib and showing marked long-term clinical response. Through this case, we highlight the importance of re-classifying papillary renal cell carcinoma subtypes to prioritize the clinical management of these cases.

Cutaneous metastases of papillary renal cell carcinoma: A case report and review of the literature

Papillary renal cell carcinoma (RCC) is an uncommon subtype of RCC that is typically encountered at early stages and has a high survival rate. Histopathology typically shows well-defined papillary architecture with tumor cells lining fibrovascular cores and can be further subdivided into type 1 and type 2 tumors based on cytology and genetic basis. Type 1 tumors have a single layer of basophilic cells and low nuclear atypia, while type 2 tumors have a pseudostratified layer of eosinophilic cells and high nuclear atypia. Some tumors have overlapping features of both types. We present a unique case of cutaneous metastases of papillary RCC with typical papillary architecture in the dermis and review the literature on this rare entity.

Histologic Diagnosis of Renal Mass Biopsy

CONTEXT.—

Core biopsy has been increasingly used for clinical decision-making in the management of patients with renal masses. The sensitivity and specificity of histologic diagnoses of renal mass biopsies depend on many factors such as adequate sampling and tissue processing, diagnostic skill and experience, and appropriate use of ancillary techniques.

OBJECTIVE.—

To review the indications, emphasize the importance of obtaining adequate diagnostic material, and introduce a general diagnostic approach, in conjunction with immunohistochemistry, in diagnosis of renal mass biopsies.

DATA SOURCES.—

Literature review and personal experiences in daily practice and consultation diagnosis of renal masses in a large tertiary medical center.

CONCLUSIONS.—

For renal mass biopsies, it is critical to obtain adequate diagnostic material and establish a standard laboratory procedure in working with small biopsy specimens. The key for the diagnosis is to be familiar with different tumor entities with characteristic morphology and to understand the wide spectrum of tumor heterogeneity. By developing a systematic approach, one can categorize the tumor and create a sensible differential diagnosis based on the growth pattern and cellular morphology. Immunohistochemistry is particularly helpful for renal mass biopsy diagnosis in selected situations.

Age-dependent changes in vancomycin-induced nephrotoxicity in mice

Vancomycin hydrochloride (VCM) is a glycopeptide antibiotic that is commonly used to eradicate methicillin-resistant gram-positive cocci, despite its nephrotoxic side effects. Elderly people are particularly susceptible to developing VCM-induced nephrotoxicity. However, the precise mechanism by which VCM induces nephrotoxicity in elderly people is not completely understood. Therefore, we investigated VCM-induced nephrotoxicity in mice of different ages. VCM was injected intraperitoneally into mice at 1, 3, 6, 12, and 24 months of age at a dosage of 400 mg/kg body weight for 3 and 14 days. Twenty-four hours after the last injection, we examined plasma creatinine levels and histopathological alterations in the kidneys. VCM administration increased plasma creatinine levels, and these values gradually increased to higher levels with aging. The histological examination revealed renal tubular degeneration, such as brush-border atrophy, apoptosis/necrosis of the tubular epithelium, and epithelial desquamation, that gradually became more severe with aging. Furthermore, immunohistochemical staining with anti-CD10 and anti-single-stranded DNA antibodies revealed damaged renal proximal tubules with marked dilatation, as well as numerous apoptotic cells, and these features increased in severity in 12- and 24-month-old mice receiving VCM. Based on these results, aged mice were highly susceptible to kidney damage induced by VCM administration. In addition, proximal tubular epithelial cells likely underwent apoptosis after the administration of VCM. This report is the first to document VCM-induced nephrotoxicity in mice of different ages. Thus, this mouse model could be useful for understanding the mechanisms of VCM-induced nephrotoxicity in the elderly.

Brief Synopsis: Review of Renal Tubule and Interstitial Anatomy and Physiology and Renal INHAND, SEND, and DIKI Nomenclature

This article provides a synopsis of the first two presentations from the second scientific session of the 37th Annual Symposium of the Society of Toxicologic Pathology in Indianapolis, Indiana, on June 18, 2018; the session focused on acute kidney injury. The first presentation, given by Dr. Kevin McDorman, focused on "Fundamentals of Renal Tubule and Interstitial Anatomy and Physiology." Several common background findings from toxicity studies were additionally discussed. Lastly, factors that impact the relevance and usefulness of historical control data, such as quality and consistency of histopathology, were discussed. The second presentation, given by Dr. Torrie Crabbs, provided a review of International Harmonization of Nomenclature and Diagnostic Criteria (INHAND), Standard for Exchange of Nonclinical Data (SEND), and drug-induced kidney injury (DIKI) nomenclature. INHAND is a global collaborative project that provides internationally accepted standardized nomenclature and diagnostic criteria for proliferative and nonproliferative changes in laboratory animals in toxicity and carcinogenicity studies. SEND is currently a required standard for data submission to the Food and Drug Administration (FDA). Since the FDA has indicated its preference for INHAND nomenclature, SEND will predominately use INHAND terminology; thus, familiarity with INHAND terminology is critical for toxicologic pathologists. The diagnostic features of three common DIKI findings, in addition to several complicated INHAND terminologies, were reviewed.

Histopathologic and Immunohistochemistry Findings in Feline Renal Cell Carcinoma

The biological behavior and immunohistochemical features of feline renal cell carcinoma (RCC) have not been well characterized. In the present study, immunohistochemical examinations were performed in 12 feline cases of RCC. The RCC consisted of solid ( n = 2), solid-tubular ( n = 2), tubular ( n = 3), papillary ( n = 2), tubulopapillary ( n = 2), and sarcomatoid ( n = 1) type lesions. Of the cases with RCC, 1 developed metastatic disease and 6 cases had no evidence of recurrence at 80 to 2292 days after surgery. One papillary-type tumor had cuboidal cells with scant cytoplasm and monomorphic nuclei, and the other had pseudostratified columnar cells with abundant cytoplasm. Immunohistochemistry revealed that the tumor cells in most cases were positive for cytokeratin (CK)7, CK20, KIT, and CD10, with the exception of cases of the solid type with clear cytoplasm (solid anaplastic), papillary type with columnar cells, and sarcomatoid types. A small number of tumor cells in the solid anaplastic and in the sarcomatoid types were positive for aquaporin-1. Increased expression of N-cadherin and Twist along with nuclear accumulation of β-catenin were observed in the sarcomatoid type. These results indicated that CK, KIT, and CD10 are relatively strongly expressed in most feline RCC. The solid anaplastic RCC exhibited CD10 expression with the absence of distal tubule marker expression. Although immunohistochemistry profiles were relatively consistent with those described in human RCC, the histopathologic features were different from those seen in humans. Epithelial-mesenchymal transition (EMT) marker expression in the current cases may suggest the involvement of an EMT-like mechanism in the development of sarcomatoid RCC in cats.

Exploring Multiphoton Microscopy as a Novel Tool to Differentiate Chromophobe Renal Cell Carcinoma From Oncocytoma in Fixed Tissue Sections

Context.—

Distinguishing chromophobe renal cell carcinoma (chRCC), especially in the presence of eosinophilic cytoplasm, from oncocytoma on hematoxylin-eosin can be difficult and often requires time-consuming ancillary procedures that ultimately may not be informative.

Objective.—

To explore the potential of multiphoton microscopy (MPM) as an alternative and rapid diagnostic tool in differentiating oncocytoma from chRCC at subcellular resolution without tissue processing.

Design.—

Unstained, deparaffinized tissue sections from 27 tumors (oncocytoma [n = 12], chRCC [n = 12], eosinophilic variant of chRCC [n = 1], and atypical oncocytic renal neoplasm [n = 2]) were imaged with MPM. Morphologic evaluation and automated quantitative morphometric analysis were conducted to distinguish between chRCC and oncocytoma.

Results.—

The typical cases of oncocytomas (12 of 12) and chRCC (12 of 12) could be readily differentiated on MPM based on the morphologic features similar to hematoxylin-eosin. The most striking MPM signature of both of the tumors was the presence of autofluorescent intracytoplasmic granules, which are not seen on hematoxylin-eosin–stained slides. Although we saw these granules in both types of tumors, they appeared distinct, based on their size, shape, cytoplasmic distribution, and autofluorescence wavelengths, and were valuable in arriving at a definitive diagnosis. For oncocytomas and chRCC, high diagnostic accuracies of 100% and 83.3% were achieved on blinded MPM and morphometric analysis, respectively.

Conclusions.—

To the best of our knowledge, this is the first demonstration of MPM to distinguish chRCC from oncocytoma in fixed tissues. Our study was limited by small sample size and only a few variants of oncocytic tumors. Prospective studies are warranted to assess the utility of MPM as a diagnostic aid in oncocytic renal tumors.

14-3-3σ Protein Expression in Canine Renal Cell Carcinomas

14-3-3σ is a protein expressed in many epithelial tissues associated with essential cell functions, including cell-cycle control, apoptosis, and cytoskeletal integrity. There is a paucity of knowledge of the tumorigenesis of canine renal cell carcinomas (RCCs), and the histological origin of this tumor has not been established. This study analyzed the expression of 14-3-3σ, Ki-67, cytokeratins, and vimentin in 40 canine RCCs. Aberrant expression of 14-3-3σ was demonstrated in 15 (38%) cases and was associated with a significantly shorter survival time ( P < .002). In contrast to canine RCC, normal kidney did not express 14-3-3σ. The Ki-67 proliferation index did not show utility as a prognostic factor. The distal convoluted tubular epithelium in normal kidneys coexpressed cytokeratins and vimentin, and thus maintenance of this coexpression pattern in canine RCC suggests that most tumors arise from the distal segment of the nephron. These results suggest that 14-3-3σ is a potential negative prognostic factor and a possible therapeutic target.

Renal cell carcinoma: the search for a reliable biomarker

One particular challenge in the treatment of kidney tumors is the range of histologies and tumor phenotypes a renal mass can represent. A kidney tumor can range from benign (e.g., oncocytoma) to a clinically indolent malignancy (e.g., papillary type I, chromophobe) to aggressive disease [e.g., papillary type II or high-grade clear cell renal cell carcinoma (ccRCC)]. Even among various subtypes, kidney cancers are genetically diverse with variable prognoses and treatment response rates. Therefore, the key to proper treatment is the differentiation of these subtypes. Currently, a wide array of diagnostic, prognostic, and predictive biomarkers exist that may help guide the individualized care of kidney cancer patients. This review will discuss the various serum, urine, imaging, and immunohistological biomarkers available in practice.

Metastatic renal cell carcinoma with undetectable renal mass presenting as lymphadenopathy

Renal cell carcinoma has the ability to metastasize to any organ; about 16 % of affected patients present initially with metastasis. However, it is rare for this tumor to present with metastasis from an unidentified primary. The current use of immunohistochemistry and molecular genetics has enabled clinicians to reach a precise diagnosis. It has been hypothesized that the treatment protocol for metastatic renal cell carcinoma can be applied to cases with undetectable primary. In this paper, a novel case of metastatic renal cell carcinoma presenting with lymphadenopathy with no evidence of a primary renal lesion is reported from Kuwait cancer center.

Metastatic Renal Cell Carcinoma Causing Small Intestinal Polyps with Intussusception: A Report of Two Cases

Renal cell carcinomas have diverse clinical presentations. Patients may present with metastatic symptoms at the time of diagnosis or years after resection of primary tumour. Small intestine is a rare site for metastatic renal cell carcinoma. Presentation as polypoid metastasis with intussusception is extremely rare. Here, we report two cases with this rare presentation. Case 1 was a 65-year-old male with multiple polypoid metastasis causing intussusception while on palliative chemotherapy for renal cell carcinoma. Case 2 was a 68-year-old female with history of nephrectomy presenting with single polypoid metastasis causing intussusception.

Pax8, Napsin A, and CD10 as Immunohistochemical Markers of Canine Renal Cell Carcinoma

Pax8, napsin A, and CD10 are useful immunohistochemical markers of human renal cell carcinoma (RCC); however, their diagnostic utility in canine RCC is unclear. Forty formalin-fixed paraffin-embedded renal cell carcinomas from dogs (15 papillary, 12 solid, and 13 tubular) and 10 metastases were evaluated for expression of Pax8, napsin A, and CD10. Thirty-nine (98%), 24 (60%), and 19 (50%) tumors expressed Pax8 (nuclear labeling), napsin A (cytoplasmic labeling), and CD10 (cytoplasmic and membranous labeling), respectively. Pax8 was expressed in 92% of solid, 100% of papillary, and 100% of tubular tumors. Napsin A was expressed in 58% of solid, 60% of papillary, and 62% of tubular RCC. CD10 was expressed in 33% of solid, 47% of papillary, and 62% of tubular RCC. Pax8 was expressed in 80% of the metastatic tumors, napsin A in 60%, and CD10 in 50%. Additionally, Pax8 immunoreactivity was stronger overall than that of napsin A or CD10. In summary, Pax8 is a more sensitive marker than napsin A or CD10 for primary and metastatic canine RCC; its nuclear and more intense reactivity also makes it easier to interpret. Tubular and papillary RCCs were more likely than solid RCC to express all 3 markers. These findings highlight the utility of Pax8 as an immunohistochemical marker in diagnosing all major subtypes of canine primary and metastatic renal cell carcinoma.

Morphologic, Molecular, and Taxonomic Evolution of Renal Cell Carcinoma: A Conceptual Perspective With Emphasis on Updates to the 2016 World Health Organization Classification

Molecular and morphologic interrogation has driven a much-needed reexamination of renal cell carcinoma (RCC). Indeed, the recently released 2016 World Health Organization classification now recognizes 12 distinct RCC subtypes, as well as several other emerging/provisional RCC entities. From a clinical perspective, accurate RCC classification may have important implications for patients and their families, including prognostic risk stratification, targeted therapeutics selection, and identification for genetic testing. In this review, we provide a conceptual framework for approaching RCC diagnosis and classification by categorizing RCCs as tumors with clear cytoplasm, papillary architecture, and eosinophilic (oncocytic) cytoplasm. The currently recognized 2016 World Health Organization classification for RCC subtypes is briefly discussed, including new diagnostic entities (clear cell papillary RCC, hereditary leiomyomatosis and RCC-associated RCC, succinate dehydrogenase-deficient RCC, tubulocystic RCC, and acquired cystic disease-associated RCC) and areas of evolving RCC classification, such as transcription elongation factor B subunit 1 (TCEB1)-mutated RCC/RCC with angioleiomyoma-like stroma/RCC with leiomyomatous stroma, RCC associated with anaplastic lymphoma receptor tyrosine kinase (ALK) gene rearrangement, thyroidlike follicular RCC, and RCC in neuroblastoma survivors. For each RCC subtype, relevant clinical, molecular, gross, and microscopic findings are reviewed, and ancillary studies helpful for its differential diagnosis are presented, providing a practical approach to modern RCC classification.

Modelling TFE renal cell carcinoma in mice reveals a critical role of WNT signaling

TFE-fusion renal cell carcinomas (TFE-fusion RCCs) are caused by chromosomal translocations that lead to overexpression of the TFEB and TFE3 genes (Kauffman et al., 2014). The mechanisms leading to kidney tumor development remain uncharacterized and effective therapies are yet to be identified. Hence, the need to model these diseases in an experimental animal system (Kauffman et al., 2014). Here, we show that kidney-specific TFEB overexpression in transgenic mice, resulted in renal clear cells, multi-layered basement membranes, severe cystic pathology, and ultimately papillary carcinomas with hepatic metastases. These features closely recapitulate those observed in both TFEB- and TFE3-mediated human kidney tumors. Analysis of kidney samples revealed transcriptional induction and enhanced signaling of the WNT β-catenin pathway. WNT signaling inhibitors normalized the proliferation rate of primary kidney cells and significantly rescued the disease phenotype in vivo. These data shed new light on the mechanisms underlying TFE-fusion RCCs and suggest a possible therapeutic strategy based on the inhibition of the WNT pathway.

A renal adenocarcinoma in a corn snake (Pantherophis guttatus) resembling human collecting duct carcinoma

A 5-year-old male captive corn snake ( Pantherophis guttatus) with caudal coelomic swelling was admitted for surgical treatment. Laparotomy revealed a 5 × 4 × 2.5 cm, firm, expansile, irregularly shaped mass arising from the middle portion of the right kidney with a mild lobulated pattern and mottled white-to-tan. Microscopically, the mass was composed of numerous bizarre angulated tubules of polygonal neoplastic cells separated by a scirrhous stroma with remarkable heterophilic infiltrates. The neoplastic cells were nonciliated and mucin secreting, with abundant brightly eosinophilic cytoplasm. There were marked cellular and nuclear atypia, frequent cell individualization, and stromal invasion, indicative of malignant behavior, which was confirmed by metastasis to the left kidney 1.5 months postoperatively. Both neoplastic epithelial cells and mesenchymal cells contributing to the scirrhous stroma had variable immunopositivity for pan-cytokeratin. The neoplasm was considered a renal adenocarcinoma resembling human collecting duct carcinoma.

Fibroblast Growth Factor Receptor-Dependent and -Independent Paracrine Signaling by Sunitinib-Resistant Renal Cell Carcinoma

Antiangiogenic therapies, such as sunitinib, have revolutionized renal cell carcinoma (RCC) treatment. However, a precarious understanding of how resistance emerges and a lack of tractable experimental systems hinder progress. We evaluated the potential of primary RCC cultures (derived from tumors and tumor grafts) to signal to endothelial cells (EC) and fibroblasts in vitro and to stimulate angiogenesis ex vivo in chorioallantoic membrane (CAM) assays. From 65 patients, 27 primary cultures, including several from patients with sunitinib-resistant RCC, were established. RCC cells supported EC survival in coculture assays and induced angiogenesis in CAM assays. RCC-induced EC survival was sensitive to sunitinib in half of the tumors and was refractory in tumors from resistant patients. Sunitinib sensitivity correlated with vascular endothelial growth factor (VEGF) production. RCC induced paracrine extracellular signal-regulated kinase (ERK) activation in EC which was inhibited by sunitinib in sensitive but not in resistant tumors. As determined by fibroblast growth factor receptor substrate 2 (FRS2) phosphorylation in fibroblasts, RCC broadly induced low-level fibroblast growth factor receptor (FGFR) signaling. Whereas ERK activation in EC was uniformly inhibited by combined VEGF/platelet-derived growth factor (PDGF)/FGF receptor inhibitors, paracrine ERK activation in fibroblasts was blocked in only a fraction of tumors. Our data show that RCC activates EC through VEGF-dependent and -independent pathways, that sunitinib sensitivity correlates with VEGF-mediated ERK activation, and that combined inhibition of VEGF/PDGF/FGF receptors is sufficient to inhibit mitogenic signaling in EC but not in fibroblasts.

Specific immunohistochemical pattern of carbonic anhydrase IX is helpful for the diagnosis of CNS hemangioblastoma

Hemangioblastomas are rare capillary-rich tumors predominantly found in the CNS. The histological appearance of these tumors varies across a broad spectrum. Several entities show considerable histomorphological similarities to hemangioblastomas. Therefore, morphological evaluation can be challenging. In this study, we evaluated the diagnostic utility of immunohistochemistry using antibodies against carbonic anhydrase IX and cytokeratin staining. Within our files, we identified 20 hemangioblastomas. A collection of 46 other tumors relevant to the differential diagnosis (12 pilocytic astrocytomas, 11 meningiomas, one pleomorphic xanthoastrocytoma, one angiomatous fibrous histiocytoma, 14 carcinoma metastases and seven gliomas grades II-IX) served as control. The pattern of strong, diffuse expression of carbonic anhydrase IX with membranous accentuation in combination with keratin negativity was considered diagnostic for hemangioblastomas. It was found in 18 out of 20 (90%) hemangioblastomas and in none of the control cases (P < 0.001). This resulted in a sensitivity of 90% and a specificity of 100%. The positive and negative predictive values were 100% and 96%, respectively. Carbonic anhydrase IX with cytokeratin is thus a highly sensitive and specific marker combination for hemangioblastomas. It is therefore very helpful in the diagnosis of these tumors and in their discrimination from other entities.

Immunohistochemical panel for differentiating renal cell carcinoma with clear and papillary features

OBJECTIVES

Renal cell carcinoma (RCC) in which clear cells with papillary architecture are present is a difficult diagnostic challenge. Clear cell RCC, rarely has papillary architecture. Papillary RCC rarely contains clear cells. However, two recently described types; clear cell papillary and Xp11 translocation RCC characteristically feature both papillary and clear cells. Accurate diagnosis has both prognostic and therapeutic implications. This study aims to highlight the helpful features of each of these entities to enable reproducible classification.

METHODS

Sixty RCC cases with clear cells and papillary architecture were selected and classified according to The International Society of Urological Pathology (ISUP) Vancouver Classification of Renal Neoplasia and graded according to The International Society of Urological Pathology (ISUP) grading system for renal cell carcinoma then stained for CK7, carbonic anhydrase IX (CA IX), α-methylacyl-CoA-racemase (AMACR) and TFE-3.

RESULTS

The characteristic immunoprofile of Clear RCC is CK7-, AMACR-, CA IX+ and TFE3-, papillary RCC is CK7+, AMACR+, CAIX- and TFE3-, while for clear cell papillary RCC it is CK7+, AMACR-, CAIX+ and TFE3- and lastly Xp11 translocation RCC is CK7-, AMACR+, CAIX- and TFE3+.

CONCLUSIONS

Staining for CA IX, CK7, AMACR and TFE3 comprises a concise panel for distinguishing RCC with papillary and clear pattern.

The Application of Immunohistochemical Biomarkers in Urologic Surgical Pathology

Context

Tumors of the genitourinary tract can be diagnostically challenging, particularly in core biopsies and cystoscopic biopsies with limited material. Immunohistochemistry is a valuable tool to use when morphology alone is insufficient for diagnosis.

Objectives

To review tumors and benign lesions of the kidney, urinary bladder, prostate gland, testis, and paratesticular structures with an emphasis on difficult differential diagnoses, as well as staining patterns in normal tissue. Recommended immunohistochemical stain panels are discussed that can assist in the diagnostic workup.

Data Sources

Review of current literature.

Conclusions

Immunohistochemistry is a valuable tool, assisting in the diagnosis of problematic tumors and benign lesions of the genitourinary tract.

Diagnostic approach to eosinophilic renal neoplasms

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

Review of the published literature and personal experience.

CONCLUSIONS

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

[The role of pathology in the diagnostics of CUP syndrome]

Cancers of unknown primary (CUP) origin account for 2-3 % of all malignancies in Germany and represent a heterogeneous, often aggressive and clinically challenging group of tumors with early metastatic dissemination for which a standardized diagnostic work-up initially fails to identify the primary site of origin at the time of diagnosis. This article reviews the options and challenges of tissue-based conventional as well as molecular diagnostic procedures to categorize this heterogeneous group of neoplasms. The role of pathology in the diagnostics of CUP syndrome is described as part of a multidisciplinary effort involving oncologists, surgeons and radiologists with the ultimate goal of assisting clinical reasoning and decision-making.