Nephroblastoma with Neuroendocrine Differentiation

A nephroblastoma (Wilms' tumor) with morphological, histochemical, immunohistochemical and ultrastructural evidence of neuroendocrine differentiation is described. Whereas areas of neural differentiation and occasional argyrophilic cells in cases of Wilms' tumor have been previously reported, the unique characteristic in this case was the extent of the neuroendocrine differentiation, as shown by a strong Grimelius stain of over 90 % of the blastematous cells. Immunoperoxidase studies employing antibodies to neuron-specific enolase and ultrastructural data were also in favor of the neuroendocrine differentiation and suggested the existence, in addition to the already reported variant of Wilms' tumor with neural differentiation, of a neuroendocrine variant which may be part of the histologic spectrum of this neoplasm.

Metanephric Adenoma of the Kidney with Massive Hemorrhage and Necrosis: Immunohistochemical, Ultrastructural, and Flow Cytometric Studies

Metanephric adenoma of the kidney is rare. We report 2 cases of metanephric adenoma with massive hemorrhage and necrosis. Case 1, a 42-year-old Japanese woman, complained of abdominal pain. Case 2, a 41-year-old Japanese woman, complained of fever and lumbago. They underwent nephrectomy. The cut surface was solid and yellow with massive hemorrhage and necrosis. These tumors showed packed tubular and glomeruloid patterns. The tumor cells were uniform and small, with uniform, oval, and hyperchromatic nuclei and scant cytoplasm, and showed reactivity for cytokeratin, vimentin, and CD 57. The MIB-1 indexes were up to 0.63%. The DNA ploidy pattern was diploid. The tumor cells formed small tubular structures with lumina and microvilli. These features suggested that metanephric adenoma is a benign tumor of an immature epithelial nature.

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

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

[Clinicopathologic features of clear cell papillary renal cell carcinoma]

OBJECTIVE

To study the clinicopathological features, differential diagnosis and prognosis of clear cell papillary renal cell carcinoma (CCPRCC).

METHODS

The histological, immunohistochemical, and molecular features were studied in 11 cases and follow-up data were also analyzed.

RESULTS

There were a total of 3 females and 8 males. The age of patients were ranged from 33 to 72 years(mean age 52.5 years). The diameters of tumors varied from 1cm to 4 cm. Histologically, papillary and cystic architecture were present at least focally in all tumors. The papillae were covered by small to medium-sized cuboidal cells with abundant clear cytoplasm and often showed extensive secondary branching, which were often folded and densely packed, resulting in a solid appearance. The nuclei were round and uniform in shape; nucleoli were not prominent (Fuhrman grade 1 or 2). Neither mitotic figures nor necrosis was present. All 11 cases exhibited moderate to strong positivity for CK7, CA9, vimentin, and HIF-1α, coupled with negative reactions for CD10, P504S, and TFE3. Ksp-cadherin was positively expressed in 8 cases.VHL gene mutations were not found in all 11 cases. Losses of chromosomes 3 (monoploid chromosome 3) was detected in 3 cases.

CONCLUSIONS

CCPRCC is uncommon and seemed to be an indolent tumor. The differential diagnosis should be included tumors, which harbor clear cell and papillary structure including clear cell renal cell carcinoma, papillary renal cell carcinoma, Xp11 translocation renal cell carcinoma, and CCPRCC. Immunohistochemical and molecular analysis may be help for its diagnosis.

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

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

Interobserver reproducibility of a grading system for chromophobe renal cell carcinoma

OBJECTIVES

To evaluate interobserver reproducibility of a grading system proposed by Paner et al. for chromophobe renal cell carcinoma.

MATERIAL AND METHODS

After selecting 23 cases of chromophobe renal cell carcinoma from the Xeral-Cíes Hospital, Meixoeiro Hospital and POVISA Hospital from the last 15 years, an informative meeting on the Paner et al. grading system criteria was held. After, the participating pathologists applied the system to each case, evaluating one slide selected. Kappa index for interobserver reproducibility was calculated, and it was classified according to the Landis and Koch scale.

RESULTS

The grading distribution was similar for most of the 6 participating observers, with grade 1 predominance. The remaining 2 observers considered a relatively higher proportion of grade 2. Kappa index values ranged from 0.136 to 0.674, with a discrete-moderate reproducibility index predominance (0.21-0.60). Highest Kappa value (0.674) was obtained between the most novel and the most expert interobservers. The lowest Kappa value was obtained among the most veteran pathologists (0.136).

CONCLUSIONS

Interobserver reproducibility for chromophobe renal cell carcinoma is discrete-moderate in our institutions when the novel grade proposed by Paner et al. is used. Labeling of grades 1 and 2 is not homogeneous among 6 participating observers. While awaiting a grading consensus on a new classification by the scientific societies, we consider that the routine use of a grading system for chromophobe renal cell carcinoma should not be used.

Possible pathogenetic relationship between Fabry disease and renal cell carcinoma

The occurrence of renal cell carcinoma (RCC) in Fabry disease (FD) is a rare event. We report a deep ultrastructural study of RCC in a patient with a previous histological diagnosis of FD. In order to highlight analogies and differences between the two histological samples, we used the nephrectomy specimen as a 'repeat biopsy', making a dynamic analysis of the evolution of the disease-related kidney damage. Secondly, a comparative ultrastructural analysis between non-neoplastic tissue and cancer demonstrated for the first time the presence of zebra bodies in the tumor cells. Finally, a hypothetical speculation about the relationship between the lysosomal accumulation, the oxidative damage and the genesis of the tumor was performed. The link connected the accumulation of glycosphingolipid globotriaosylceramide, characteristic of FD, with the expression of CD74 and macrophage migration inhibitory factor that may play an important role in tumorigenesis regulated by the Von Hippel-Lindau/hypoxia-inducible factor 1α pathway.

Renal cell carcinoma and oxidative stress: The lack of peroxisomes

Oxidative stress plays an important role in carcinogenesis because of induction of DNA damage and its effects on intracellular signal transduction pathways. Here, we investigated the relationship between the defence against oxidative stress and human renal cell carcinoma that originates from proximal tubular epithelium. Oxygen insensitivity of the histochemical assay of glucose-6-phosphate dehydrogenase (G6PD) activity is a diagnostic tool for the detection of carcinomas. Its mechanism is based on high G6PD activity, reduced superoxide dismutase activity and reduced numbers of peroxisomes in the cancer cells. Five out of the 8 renal carcinomas studied here demonstrated oxygen insensitivity. These carcinomas showed high G6PD activity, whereas the other 3 carcinomas contained lower G6PD activity and were oxygen sensitive like non-cancer cells. Oxygen insensitivity did not correlate with tumour grade, staging or presence of metastases. Electron microscopy and immunofluorescence of catalase showed large numbers of peroxisomes in epithelial cells of proximal tubules of normal human kidney, whereas these organelles were completely absent in cancer cells of all carcinomas. As a consequence of the absence of peroxisomes in cancer cells, fatty acid metabolism is disturbed in addition to the altered glucose metabolism that is generally observed in cancer cells. Therefore, therapeutic approaches should focus on metabolism in addition to other strategies targeting signal transduction and angiogenesis.

Imprint cytologic features in renal cell carcinoma associated with Xp11.2 translocation/TFE3 gene fusion in an adult: a case report

BACKGROUND

Adult-onset renal cell carcinoma (RCC) associated with Xp11.2 translocation/TFE3 gene fusion is a very rare tumor. To date, there are no reports on immunocytochemical study of the primary tumor. We describe such a case that we diagnosed by immunocytochemistry of imprint cytology material.

CASE

A 46-year-old man was found to have a mass in the lower pole of the right kidney. Magnetic resonance imaging (MRI) T2-weighted images showed a hypointense area in the tumor, and papillary RCC was suspected. Imprint cytology showed tumor cells that were isolated or arranged in large or small papillary clusters. Irregularly shaped large oval nuclei, finely granular chromatin and a single large nucleolus were noted. Cytoplasm was abundant and admixed with clear and granular eosinophilic patterns and scattered large vacuolated cells. Almost all tumor cells diffusely expressed immunocytochemical reactivity to TFE3 protein. Hyaline nodules were observed in the stroma. Ultrastructurally, neoplastic cells contained rhomboid crystals identical to those of alveolar soft part sarcoma.

CONCLUSION

The immunocytochemistry of TFE3 protein may be a powerful tool for accurate diagnosis when RCC associated with Xp11.2 translocation/TFE3 gene fusion is suspected by imprint cytology even in adult-onset cases, and cytotechnologists should accurately recognize cytologic findings of this tumor.

The Evolving Concept of Renal Neoplasia: Impact of Emerging Molecular and Electron Microscopic Studies

The classification of renal tumors has evolved from one that initially encompassed only 2 types of tumors, i.e., clear and granular cell carcinomas, to the markedly expanded recent classification that incorporates new entities, some of which are primarily defined by specific molecular abnormalities. Despite these advances, a single tumor category, clear cell carcinoma, still incorporates the majority (approximately 70%) of renal tumors. It is, however, postulated that this single category is likely to encompass several different tumor types that are, at present, undifferentiated. Electron microscopic studies have been pivotal in defining the spectrum of oncocytoma-chromophobe renal cell carcinoma. Cytoplasmic eosinophilia found in some renal cell carcinomas currently classified as clear cell type is under intense study. Tumors that have recently emerged from this group include tumors with translocations involving chromosome Xp11.2, carcinomas associated with neuroblastoma and epithelioid angiomyolipoma. The spectrum of renal tumors seen in younger patients is wider than among older patients, with rare and unusual tumors being more likely seen in younger patients. The author concludes that although the routine application of electron microscopy to kidney tumor diagnosis may not be practical, systematic ultrastructural studies of these tumors may aid in the definition of new entities.

Ultrastructural Studies in a Series of 18 Cases of Chromophobe Renal Cell Carcinoma

Chromophobe renal cell carcinoma (CRCC) is a distinct variant of renal epithelial neoplasm. Ultrastructurally, the presence of numerous cytoplasmic microvesicles is highly characteristic of CRCC, as are mitochondria with tubulovesicular cristae. All 18 cases is this study present these two elements with a different distribution, depending on the morphological variant (typìcal or eosinophilic). In both variants, the mitochondria show tubulovesicular cristae and budding from the outer mitochondrial membrane that is very similar to the cytoplasmic microvesicles. An association was also found between intracristal mitochondrial swelling and bud formation. These buds, when detached from the mitochondrial membrane, may convert into the cytoplasmic microvesicles.

Mixed Epithelial and Stromal Tumor of the Kidney: Preliminary Immunohistochemical and Electron Microscopic Studies of the Epithelial Component

Mixed epithelial and stromal tumor of the kidney is a rare biphasic tumor composed of cysts and tubules embedded in the spindle cell stroma. Although the histogenesis of this tumor is unknown, it has been proposed that both components of the tumor, i.e., stromal and epithelial, are neoplastic. The authors report preliminary immunohistochemical and electron microscopic studies of the epithelial component from one case of a typical, benign, mixed epithelial, and stromal tumor of the kidney. In this study, some tubules showed positivity for proximal, while others showed positivity for distal, nephron immunomarkers. By electron microscopy, some tubules had features of proximal tubular epithelium, while other tubules had features of the loop of Henle (thin segments). The authors believe that in a benign tumor such morphologic heterogeneity is inconsistent with neoplastic proliferation. Therefore, they postulate that in mixed epithelial and stromal tumor of the kidney the tubules are entrapped rather than neoplastic. Additional studies are needed to address this issue and electron microscopy should play a significant role in this process.

Renal papillary carcinoma classification into subtypes may be reproduced by nuclear morphometry

OBJECTIVE

To analyze relationships between nuclear features of papillary renal cell carcinoma (PapRCC) subtypes.

STUDY DESIGN

The material for the study consisted of 53 cases, of which 29 were type 1, 17 type 2 and 7 intermediate. At least 100 nuclei per case were segmented from images of 4',6-diamidino-2-phenylindole-stained slides. The geometric and texture features were extracted and used for analysis.

RESULTS

In analysis of variance, it was shown that both individual cases and tumor types differ in the majority of the parameters. On nonsupervised expectation-maximization clustering, it was possible to classify the nuclei into separate categories, but PapRCC classes were not reproduced. The neural network classified the nuclei with sensitivity >0.6 and specificity >0.75. Analyzing the results for individual cases, the nuclei of type 1 cases were properly classified in 74-91%, nuclei of type 2 cases in 58-80% and nuclei of intermediate cases in 53-70%.

CONCLUSION

Our findings show that PapRCC subtypes are distinct enough to be reproduced by image analysis.

Primary small cell neuroendocrine carcinoma of the kidney: morphological, immunohistochemical, ultrastructural, and cytogenetic study of a case and review of the literature

Poorly differentiated neuroendocrine carcinomas (PDNECs) of the kidney are extremely rare high-grade cancers accounting for only 42 cases reported in the literature. In this paper, we describe the morphological, immunohistochemical, ultrastructural, and for the first time, cytogenetic features of a renal PDNEC. In addition, we have reviewed the literature and compared the published clinicopathological data with our morphological and genetic results. The tumor arose within the kidney parenchyma and showed the typical histological features of a pure small cell PDNEC. Fluorescence in situ hybridization study demonstrated a complex chromosomal assessment indicative of a high degree of chromosome instability with gain of multiple chromosomes, loss of p53, and amplification of myc gene. These results suggest that renal PDNEC has a different genetic background to renal clear cell carcinoma, mainly characterized by the loss of the short arm of chromosome 3. Conversely, genetic alterations seem to resemble those of type 2 papillary renal cell carcinoma. The review of the literature demonstrated that PDNECs are associated with poor prognosis and that parenchymal tumors show some differences from those arising in the pelvis, in that parenchymal tumors are purely neuroendocrine while pelvic tumors are mostly mixed neuroendocrine-exocrine neoplasms.

Caki-1 cells represent an in vitro model system for studying the human proximal tubule epithelium

BACKGROUND/AIMS

The human proximal tubule (PT) epithelium is distinguished from other nephron segments via several unique characteristics. Studies assessing PT epithelium increasingly employ cell lines, bypassing the complexity of primary cell cultures. However, few human model systems exist for studying PT cells in vitro. The current work involves an intensive characterization of Caki-1 cells, a commercially available human renal cell line.

METHODS

Caki-1 cells were validated as a representative model system for PT cell research via morphological, physiological and biochemical investigations including light and transmission electron microscopy, transepithelial electrical resistance (TER) measurements and the detection of PT markers.

RESULTS

Morphologically, these cells form a polarized monolayer with apical located microvilli and multiple mitochondria per cell. Low TER ranging from 2 to 28 Omega cm(2) was determined for Caki-1 cells, characteristic of the 'leaky' PT epithelium in vivo. Expression of the PT markers: NHE3, GGT, DPP IV, APM and AP were present in Caki-1 cells. Two epithelial markers, E-cadherin and Na(+)/K(+)-ATPase, were additionally observed.

CONCLUSION

The current work is a concise summary which confirms that Caki-1 cells represent well-differentiated polarized PT cells in vitro, regardless of its cancerous origin and multiple passaging. They prove to be a significant contribution to the field of PT research.

Glomus tumor of the kidney: a report of 3 cases involving renal parenchyma and review of the literature

Glomus tumor is a rare mesenchymal neoplasm affecting the subcutaneous tissue of the distal extremities in the majority of cases. It only rarely involves visceral organs. We report 3 cases of the glomus tumor family in the kidney, a solid glomus tumor, a glomangioma, and a glomangiomyoma. All 3 tumors involved the renal parenchyma and occurred in 3 men aged 36, 81, and 48 years, respectively. All 3 tumors were well-circumscribed and showed morphology otherwise identical to those seen in soft tissue. All 3 tumors were immunoreactive for actin and negative for desmin and S100 and only 1 tumor expressed CD34 in tumor cells. To date, all 3 tumors have followed a benign course without evidence of recurrence or metastasis. This report expands the spectrum of mesenchymal tumors of the kidney.

Renal leiomyoma: an immunohistochemical, ultrastructural and comparative genomic hybridization study

Renal leiomyoma is a rare neoplasm. We report such a case in a 57-year-old Japanese woman who was found to have a mass in the left kidney. The histological examination disclosed the proliferation of spindle cells showing a benign appearance. Entrapped tubular cells were observed in the peripheral area of the tumor. The immunohistochemical examination of spindle neoplastic cells showed a positive reaction for alpha smooth muscle actin, h-caldesmon, l-caldesmon, calponin, muscle actin, myosin and desmin. Additionally, the ultrastructural examination of the tumor showed membrane caveolae and myofilaments in the cytoplasm. This tumor was considered to show a differentiation into smooth muscle cells. The comparative genomic hybridization of the tumor detected the combined losses of chromosomes 4, 6, 12 and 14 which has not been previously described in renal tumors. Finally, the immunohistochemical panel of smooth muscle markers and ultrastructural and genetic study may be useful in diagnosing renal leiomyoma.

Desmoplastic Small Round Cell Tumor of the Kidney in Childhood

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that generally manifests as abdominal paraserosal masses and affects mainly male adolescents and young adults. When presenting within visceral organs, the diagnosis of DSRCT poses significant difficulties.

METHODOLOGY

Four primary renal DSRCT in children diagnosed during a 3-year period are the basis of this report. The medical records and pathologic material were reviewed, including immunohistochemical, ultrastructural, and cytogenetic/molecular studies.

RESULTS

The age at presentation was 6 to 8 years, and all children presented with a left renal mass. The tumors measured 3.7 to 13.4 cm and consisted of nests, cords, or sheets of small undifferentiated cells with foci of necrosis and calcification. Desmoplasia was not seen. Tumor cells were immunopositive for vimentin, WT-1 (monoclonal and polyclonal), desmin, cytokeratin, and epithelial membrane antigen. A distinct paranuclear dotlike pattern was observed with vimentin and desmin. Tumor cells possessed rare or focal immunoreactivity for platelet derived growth factor-A and transforming growth factor-beta3, which have been implicated in the pathogenesis of desmoplasia in DSRCT. The EWS-WT1 t(11;22)(p13;q12) translocation was demonstrated in all 4 tumors by fluorescence in situ hybridization and/or reverse transcription-polymerase chain reaction.

CONCLUSIONS

DSRCT should be considered in the differential diagnosis of renal tumors composed of small round cells. Undifferentiated morphology and lack of desmoplasia contribute to the difficulty in its recognition. Ancillary studies such as immunohistochemistry may suggest the diagnosis, but cytogenetic and molecular genetic studies are required for confirmation.

Aberrant expression of apoptosis proteins and ultrastructural aberrations in uterine leiomyomas from patients with hereditary leiomyomatosis and renal cell carcinoma

OBJECTIVE

To examine differences between sporadic and familial uterine leiomyomata related to expression of apoptosis-related proteins and tumor ultrastructure.

DESIGN

Expression of apoptosis-related proteins was measured by immunohistochemistry. Tumor ultrastructure was evaluated by transmission electron microscopy.

SETTING

Human genetics laboratory.

PATIENT(S)

Patients confirmed for hereditary leiomyomatosis and renal cell carcinoma (HLRCC), and anonymous archival sporadic leiomyoma patients.

INTERVENTION(S)

Samples for electron microscopy were collected from myomectomy and hysterectomy with informed consent. Other samples were archival.

MAIN OUTCOME MEASURE(S)

Intensity of immunohistochemistry staining and evaluation of electron micrographs.

RESULT(S)

Immunohistochemistry revealed increases in expression of antiapoptotic Bcl-2 and the proliferation factor proliferating cell nuclear antigen (PCNA) in both sporadic and HLRCC uterine leiomyomata. Furthermore, we observed an increase in antiapoptotic Bcl-x and a concurrent decrease in proapoptotic Bak solely in HLRCC leiomyomas. We also observed ultrastructural alterations in HLRCC and sporadic leiomyomas, particularly pertaining to extracellular matrix and intermediate filament aggregation.

CONCLUSION(S)

The observed alterations in expression of apoptosis-related proteins indicate a shift in both HLRCC and sporadic leiomyomas to increased resistance to apoptosis compared with myometrium, which appears to be stronger in HLRCC leiomyomas. The changes observed in HLRCC leiomyomas appear to be related to activation of the hypoxia pathways. The results suggest not only a partial overlap in the pathogenic mechanism of the two tumor types, but also intriguing differences.

Nucleolar grade but not Fuhrman grade is applicable to papillary renal cell carcinoma

This study was undertaken to determine the validity of Fuhrman grading in a series of papillary renal cell carcinomas (PRCCs), to examine the interrelationship and prognostic significance of the individual components of the grading system, and further to determine whether any observed predictive value was independent of other prognostic indicators. Ninety cases of PRCC were studied. Fifty-nine tumors were of type 1 and 31 were of type 2. There were 33 TNM stage 1, 26 stage 2, 18 stage 3, and 12 stage 4 tumors, whereas division of cases according to pT category showed 14 pT1a, 20 pT1b, 25 pT2, 15 pT3a, 4 pT3b, and 11 pT4 tumors. Ten tumors were grade 1, 58 grade 2, and 22 grade 3 when predominant Fuhrman grade was assigned, whereas grading according to the high-power field containing the highest grade (focal grade) showed 40 grade 2, 49 grade 3, and 1 grade 4 tumors. Measurements of nuclear size (area, major axis, perimeter) and shape (shape factor, compactness) were undertaken using image analysis. Nuclear area ranged from 27.63 to 116.39 microM, major axis length 6.70 to 14.06 microM, and nuclear perimeter 20.05 to 41.77 microM. Shape factor ranged from 0.805 to 0.878 and compactness from 14.33 to 15.66. Predominant nucleolar grade using the criteria of the Fuhrman classification was nucleolar grade 1 for 13 tumors, nucleolar grade 2 for 56 tumors, and nucleolar grade 3 for 21 tumors. Focal nucleolar grade based on the high-power field showing the greatest degree of nuclear pleomorphism, was grade 2 for 38 tumors and grade 3 for 52 tumors. pT category, TNM stage, focal Fuhrman grade, and PRCC type were significantly associated with survival. Of the various measures of the components of the Fuhrman classification, only focal nucleolar grade was associated with survival, on univariate analysis. On multivariate analysis, focal nucleolar grade and tumor diameter were independently associated with survival, whereas TNM stage retained significance independent of other parameters. It is concluded that assessment of nucleolar prominence rather than Fuhrman grade is applicable for stratification of tumors within TNM stage or pT category for PRCC and that this should be based upon the high-power field showing the greatest degree of nuclear pleomorphism.

Shock wave induced cytoskeletal and morphological deformations in a human renal carcinoma cell line

Effects of shock waves on the morphology and cytoskeleton of a human renal carcinoma cell line (ACHN) were investigated in vitro. ACHN monolayer cultured on a cover slide glass was treated with 10 shots of focused underwater shock waves, with 16 MPa peak pressure at the focal area of a piezoceramic shock wave generator. After exposure to the shock wave, based on the severity of morphological deformations of the treated cells, the monolayer was divided into three morphological areas; focal, marginal and intact. Morphological deformations were found to be associated with disorganization of the intracellular cytoskeletal filaments. Deformation of the cytoskeletal proteins in the treated cells were separately studied with respect to the location of the cells within the three morphological areas. Among three major cytoskeletal proteins, actin and tubulin, but not vimentin, were affected by the shock waves. The deformed cells reorganized their cytoskeletal network within 3 h with a pattern similar to the control, indicating the transient characteristic of the shock wave induced cytoskeletal damage in the surviving cells. The remaining cell fragments on the slide glass, which contained short actin filaments, indicated the important role of shear stress in damaging the cytoskeletal fibers by shock waves.

Eosinophilic cytoplasmic inclusions in papillary renal cell carcinoma

A case of a patient with papillary renal cell carcinoma (RCC) with eosinophilic inclusions is presented. Almost all neoplastic cells contained eosinophilic globules that were stained red by trichrome and were negative for periodic acid-Schiff (PAS) reaction. Immunohistochemically, globules were negative for actin, keratin, vimentin, glially fibrillary acidic protein (GFAP), and neurofilament. Ultrastructurally, globules consisted of electron-dense granular material that is more suggestive of a secretory substance than cytoskeletal filaments. The presence of eosinophilic cytoplasmic inclusions in RCC is rare. In this article, we review similar cases in the literature and discuss the nature of eosinophilic globules.

Fibrin microbeads (FMB) as a 3D platform for kidney gene and cell therapy

Cell and gene therapy may alter the outcome of renal diseases, such as hereditary nephropathies, acute and chronic glomerulonephritis and allograft nephropathy. However, owing to blockade of many viral and cellular vehicles by the complex glomerular architecture, the exact nature of gene and cell delivery into specific renal compartments remains currently unknown. To study the interaction of viral vectors with a variety of renal cells and mesenchymal stem cells (MSCs), we employed a novel biological three-dimensional (3D) matrix comprised of fibrin microbeads (FMB) in comparison to monolayer cell culture. Our studies showed that renal cells of both established and primary lines can grow efficiently on FMB and differentiate into epithelial structures, as shown by electron microscopy. Gene delivery into renal cells in 3D was observed for several viral vectors and growth in 3D on FMB conferred resistance to renal cancer cells in the context of oncolytic adenoviruses. Finally, MSCs from various rodent species attached to FMB, grew robustly, survived for several weeks and could efficiently be transduced on FMB. Thus, on the basis of growth, differentiation and transduction of renal cells in 3D, FMB emerge as a novel 3D cellular microenvironment that differs substantially from monolayer cell cultures.

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.

Protein extraction from formalin-fixed, paraffin-embedded tissue sections: quality evaluation by mass spectrometry

A satisfactory protocol of protein extraction has been established based on the heat-induced antigen retrieval (AR) technique widely applied in immunohistochemistry for archival formalin-fixed, paraffin-embedded (FFPE) tissue sections. Based on AR, an initial serial experiment to identify an optimal protocol of heat-induced protein extraction was carried out using FFPE mouse tissues. The optimal protocol for extraction of proteins was then performed on an archival FFPE tissue of human renal carcinoma. FFPE sections were boiled in a retrieval solution of Tris-HCl containing 2% SDS, followed by incubation. Fresh tissue taken from the same case of renal carcinoma was processed for extraction of proteins by a conventional method using radioimmunoprecipitation assay solution, to compare the efficiency of protein extraction from FFPE tissue sections with extraction from fresh tissue. As a control, further sections of the same FFPE sample were processed by the same procedure without heating treatment. Evaluation of the quality of protein extracted from FFPE tissue was done using gel electrophoresis and mass spectrometry, showing most identified proteins extracted from FFPE tissue sections were overlapped with those extracted from fresh tissue.

[Wilms tumor as a novel model of angiogenesis in childood nephropathies]

Wilms tumor has a unique possibility of recapitulation within its substance different stages of renal development. Vascular endothelial growth factor (VEGF) and its receptors (VEGFR-1 and VEGFR-2) are regarded to play the crucial role in the process of simultaneous development of tubules and glomeruli in animal kidney. Neoangiogenesis, secondary to rearrangement of epithelial elements in Wilms tumor, may therefore follow the lack of glomeruli in this neoplasm. The aim of the present research was an immunohistochemical analysis of VEGF-C and VEGFR-2 expressions in Wilms tumor and an attempt of explanation of neovascularisation process in this malignancy. The study group was composed of 16 children diagnosed with Wilms tumor (stage III of clinical classification) hospitalised in Department of Paediatric Oncology, Hematology and Transplantology, University of Medical Sciences in Poznan. The indirect immunohistochemical assay with the use of monoclonal antibodies directed against VEGF-C and VEGFR-2 was employed. VEGF-C expression was detected within blastemal and hypocellular stromal components of Wilms tumor. On the other hand, immuno-reactivity of VEGFR-2 was established in dysplastic tubules in the closest proximity of VEGF-C positive parts of stromal origin. VEGF-C dependent neovascularisation in Wilms tumor may follow an adequate differentiation of already existing epithelial elements. It may also explain the process of glomeruli-dependent physiological development of kidney and, what is also probable, the phenomenon of neoangiogenesis described in individual childhood nephropathies.

[Angiomyolipoma of the kidneys]

59 angiomyolipomas were studied: immunohistochemistry (IHC) was used in 24 cases, electron microscopy (EM) in 6 cases. 57 tumors had a typical structure, 2 did not contain fat component. Premelanosomes were found by EM in one tumor. Smooth muscle actin was found in all tumor cells. Involvement of lymph nodes was observed in 2 patients. Histogenesis of this tumor is discussed.

The VEGF receptor tyrosine kinase inhibitor, ZD6474, inhibits angiogenesis and affects microvascular architecture within an orthotopically implanted renal cell carcinoma

The proangiogenic vascular endothelial growth factor-A (VEGF) is essential for the development of new tumor vessels. ZD6474 is a novel inhibitor of VEGF receptor-2 (VEGFR-2) tyrosine kinase activity, which also has additional activity against epidermal growth factor (EGF) receptor tyrosine kinase. The antitumor activity of different schedules of ZD6474 in a clinically relevant, metastasizing, murine renal cell carcinoma (RENCA) model was evaluated in this study. RENCA cells were inoculated into the left kidney of 24 mice (day 0). Daily ZD6474 (50 mg/kg p.o.) treatment was initiated 1 day or 10 days after tumor cell inoculation and continued until day 21. Following treatment, kidney weight and volume were assessed and blood vessel density determined by CD31 staining. Visible metastases in the lungs, spleen, and lymph nodes were quantified using a dissection microscope. In an additional study, animals were treated according to the same regimen and quantitative three-dimensional microvascular corrosion casting was performed to enable detailed assessment of the tumor vascular architecture. Therapy initiated on day 1 or day 10 resulted in a 79% and 59% reduction in primary tumor volume, a 79% and 60% reduction in the number of lung metastases, and a 58% and 59% reduction in vessel density of primary tumors compared with the control group, respectively. Corrosion casting proved a 5.4- and 3.2-fold lower vascular volume compared with untreated tumors, observations that paralleled with significant architectural alterations. In this RENCA model, ZD6474 was a highly active inhibitor of tumor angiogenesis, primary tumor growth and tumor metastasis.

[Clinicopathological study of 4 renal juxtaglomerular cell tumors]

OBJECTIVE

To investigate the clinical characteristics, morphologic and immunohistochemical features, diagnosis, differential diagnosis, histogenesis and prognosis of renal juxtaglomerular cell tumor (JGCT).

METHODS

Light microscopic observation; immunohistochemical assay of CK8, E-cadherin/CK7, CD10, Vim, Actin, CD34, S100, HMB45, CD31, Chr, Syn and CD117, EM; and follow-up were done on all 4 surgically treated JGCT patients.

RESULTS

All 4 JGCT were observed in young adult with clinically uncontrolled severe hypertension. Grossly, the tumor was encapsulated and small in size. Microscopically, the tumor cells grew in sheets predominantly, but papillary and onion-like pattern could also be seen. The stroma contained prominent vasculature that consisted of numerous thin-wall vessels clustering around thick-walled vessels. Tumor cells were rather small, polygonal, with slightly eosinophilic cytoplasm and ill-defined cell border. Nuclei were uniform in size but nuclear atypia and mitosis could be seen. Numerous mast cells were scattered among the tumor cells, and tubules were identified in 3 of 4 cases with positive expression of distal tubule marker of E-cadherin/CK7. Tumor cells positively expressed Vim, Actin, calponin, and CD34. All cases presented ultrastructural features of distinct rhomboid-shaped crystal. There was no recurrence or metastasis but hypertension persisted in three during follow-up (mean 37 months) for all 4 JGCT patients.

CONCLUSION

JGCT, originating from the juxtaglomerular cell, has a distinct benign entity, and it is typically found in young adults with severe hypertension. It has a unique morphology and ultrastructure features and positive immunoreactivity to Vim, Actin, calponin and CD34.

Unusual eosinophilic variant of chromophobe cell renal carcinoma--an ultrastructural diagnosis

A case of eosinophilic variant of chromophobe cell renal carcinoma (EVCCRC), an uncommon variety of renal cell carcinoma, occurred in a 72 year old male. The most problematic differential diagnosis was renal oncocytoma, as the two entities share overlapping features on histology, yet differ completely in biological behavior. EVCCRC is a potentially malignant neoplasm whereas renal oncocytoma is totally benign. Staining with Hale's Colloidal Iron using modified Mowry's technique showed granular cytoplasmic positivity. The diagnosis was confirmed by ultrastructural examination of the tumor which revealed unique features of EVCCRC like presence of numerous cytoplasmic microvesicles along with mitochondria displaying tubulo-vesicular cristae. This case delineates the role of electron microscopic examination as the sole means to differentiate EVCCRC from renal oncocytomas.

Cyclooxygenase-2 expression and relationship to tumour progression in human renal cell carcinoma

AIMS

Cyclooxygenase (COX), which catalyses the synthesis of prostaglandins from arachidonic acid, has two isoforms; COX-1 and COX-2. There is ample evidence to suggest an important role for COX-2 in cancer. The aim of this study was to evaluate the clinical significance of COX-2 expression and its localization in the development and progression of human renal cell carcinoma (RCC).

METHODS AND RESULTS

The expression and localization of COX-2 were evaluated in human RCC tissues from 75 patients by immunohistochemistry. Immunoreactive COX-2 protein was observed in all cases of RCC, and the levels of COX-2 expression were correlated with tumour grade and pathological stage. Expression of COX-2 was higher in the granular cell subtype than in the clear cell subtype of RCC. Immunoelectron microscopy revealed that COX-2 was expressed in the nuclear membrane, rough endoplasmic reticulum, Golgi complex and mitochondrial membrane of RCC cells.

CONCLUSION

COX-2 overexpression within these intracellular organelles in RCC may be associated with renal cell carcinogenesis and COX-2 may be a useful biomarker in RCC.

Chromophobe renal cell carcinoma: a comparative study of histological, immunohistochemical and ultrastructural features using high throughput tissue microarray

AIMS

In some cases distinction between chromophobe renal cell carcinoma (CRCC), oncocytoma and clear cell (conventional) renal cell carcinoma (eosinophilic variant) using routine light microscopy remains problematic. The present study investigates the level of agreement in the diagnosis of CRCC, as well as the histological features most frequently used for this diagnosis by two pathologists with a special interest in renal neoplasia. The sensitivity and specificity of immunohistochemical markers in cases with overlapping histological features in the diagnosis of CRCC were also studied. Electron microscopy was performed, as a diagnostic gold standard, on all of the cases.

METHODS AND RESULTS

Thirty-two renal tumours with predominantly eosinophilic cytoplasm were reviewed in a blinded fashion by two pathologists. The diagnosis and morphological features used to render each diagnosis were tabulated. Validation of the utility of keratin 7 and 20, epithelial membrane antigen (EMA), vimentin, CD10, parvalbumin, RCC antigen, antimitochondrial antibody and Hale's colloidal iron was performed by the construction of a tissue microarray (TMA) master block. Based on histological criteria alone, overall agreement on the diagnosis of these tumours was reached in 69% of the cases, while there was total disagreement in 12%. In 59% of the cases, total agreement was reached in classifying the case as a CRCC based on histology alone. Kappa statistics for interobserver variability were calculated as only slight agreement (kappa = 0.3). The histological features most frequently associated with a diagnosis of CRCC were accentuated cell borders (87%) and a combination of hyperchromatic wrinkled nuclei (79%) and perinuclear halos (74%). The most sensitive and specific marker for CRCC was parvalbumin (sensitivity 0.91; specificity 1.0). The immunohistochemical profile of EMA+/ vimentin- was useful but had low specificity (sensitivity 0.75; specificity 0.4). CD10 had the highest sensitivity (1.0) but worst specificity (0.25) for CRCC. Keratin 7 had high sensitivity (0.83) but fairly low specificity (0.37) for CRCC. Hale's colloidal iron and the RCC antigen marker were not contributory. Finally, the antimitochondrial antibody was found to be fairly sensitive (0.83) for excluding CRCC.

CONCLUSIONS

A small but significant proportion of renal tumours with cells having eosinophilic cytoplasm cannot be classified, even by experienced pathologists, based on histology alone. In these cases it is imperative to use markers with known sensitivity and specificity for the diagnosis of CRCC.

SONOGRAPHIC FEATURES OF HISTIOCYTIC NEOPLASMS IN THE CANINE ABDOMEN

The purpose of this retrospective study was to describe the ultrasonographic features of malignant histiocytosis (MH), malignant fibrous histiocytoma, and histiocytic sarcoma in abdominal organs of dogs. The medical records of 18 dogs that had undergone abdominal sonography and had a histopathologic diagnosis of abdominal MH, malignant fibrous histiocytoma, and histiocytic sarcoma were reviewed. The organ most commonly affected was the spleen. MH was the most common followed by histiocytic sarcoma and malignant fibrous histiocytoma. In the spleen there were often multiple hypoechoic nodules with well-defined borders. In one dog, without focal lesions, the spleen was enlarged and hypoechoic. The liver was the second most commonly affected organ. MH was most common followed by histiocytic sarcomas and malignant fibrous histiocytoma. The most common sonographic feature in the liver was the presence of multiple hypoechoic nodules with well-defined borders. One dog without hepatic nodules had a liver that was ultrasonographically enlarged and hypoechoic. MH in the abdominal lymph nodes resulted in hypoechoic lymphadenopathy. Malignant fibrous histiocytoma was the only neoplastic type in the kidneys appearing as a single heteroechoic renal mass with well-defined borders. MH was observed in the stomach of one dog. Sonographically there was a single well circumscribed hypoechoic mass with well-defined borders and abnormal stomach layers. In this study it was not possible to differentiate between MH, malignant fibrous histiocytoma, and histiocytic sarcoma using sonography.

Immunohistochemical identification of intracytoplasmic lumens by cytokeratin typing may differentiate renal oncocytomas from chromophobe renal cell carcinomas

Renal oncocytomas and chromophobe renal cell carcinomas (RCCs) share a common phenotype and both originate from the intercalated cells of the collecting duct. This makes it very difficult to differentiate between the two tumors immunohistochemically. Therefore, we studied the results of immunohistochemistry focusing on certain characteristic structures that are occasionally present in renal oncocytomas. We carried out Hale's colloidal iron staining and immunohistochemistry for various cytokeratins (cytokeratins 7, 8, 10, 10/13, 14, 18, 19 and 20, and AE1/AE3) in four oncocytomas and six chromophobe RCCs. In addition, one renal oncocytoma and one chromophobe RCC were studied using electron microscopy. Two renal oncocytomas and one chromophobe RCC were completely unstained by colloidal iron. There was no evident difference between the immunohistochemical characteristics of oncocytomas and those of chromophobe RCCs. However, in all four renal oncocytomas we identified intracytoplasmic ring-like positive reactions for some cytokeratins (at least 3 antigens of cytokeratins 7, 8 and 19, and AE1/AE3), which corresponded ultrastructurally to the intracytoplasmic lumens (ICLs). In contrast, no such structures were found in any of the chromophobe RCCs using the antibodies employed. Therefore, immunohistochemical identification of ICLs by cytokeratin typing may be useful for differentiating between renal oncocytomas and chromophobe RCCs and be more sensitive in this respect than colloidal iron staining.

Primary de novo malignant giant cell tumor of kidney: a case report

Background

Osteoclast-like giant cell tumors are usually observed in osseous tissue or as tumors of tendon sheath, characterized by the presence of multinucleated giant cells and mononuclear stromal cells. It has been reported in various extraosseous sites including breast, skin, soft tissue, salivary glands, lung, pancreas, female genital tract, thyroid, larynx and heart. However, extraosseus occurrence of such giant cell tumors in the kidney is extremely rare and is usually found in combination with a conventional malignancy. De-novo primary malignant giant cell tumors of the kidney are unusual lesions and to our knowledge this is the second such case.

Case Presentation

We report a rare case of extraosseous primary denovo malignant giant cell tumor of the renal parenchyma in a 39-year-old Caucasian female to determine the histogenesis of this neoplasm with a detailed literature review.

Conclusion

Primary denovo malignant giant cell tumor of the kidney is extremely rare. The cellular origin of this tumor is favored to be a pluripotential mesenchymal stromal cell of the mononuclear/phagocytic cellular lineage. Awareness of this neoplasm is important in the pathological interpretation of unusual findings at either fine needle aspiration or frozen section of solid renal masses.

Renal oncocytosis presenting in childhood: a case report

Renal oncocytosis is a rare condition in which a spectrum of oncocytic lesions, including oncocytomas, diffusely involve the kidney. Few cases have been reported and all were in adult patients. We report here such a case in a 12-year-old girl. In addition to the unusual age at presentation, this case is remarkable for its heterogeneous tumor morphology, with some areas containing chromophobe carcinoma-like cells. Electron microscopy, immunohistochemistry, Hale's colloidal iron staining, and cytogenetics were performed to further evaluate the different morphologic areas. Our results suggest that the cells in the chromophobe carcinoma-like areas do not fulfill all the diagnostic criteria of chromophobe carcinoma. We caution pathologists in making a malignant diagnosis in such cases, especially in younger patients.

Primitive neuroectodermal tumor of the kidney. Report of a case initially diagnosed by fine needle aspiration cytology

BACKGROUND

Primitive neuroectodermal tumor (PNET) is a malignant small round cell tumor that exhibits neuroepithelial differentiation, most often presenting as a bone or soft tissue mass in the trunk or axial skeleton in adolescents and young adults. Isolated cases of PNET have been observed at visceral sites, such as the ovary, testis, uterus, bladder and pancreas. We present a case of PNET in the kidney initially diagnosed by fine needle aspiration (FNA).

CASE

A 21-year-old woman presented with microhematuria. Urine cytology was negative for malignant cells. Physical examination was without abnormal findings. Computerized tomography revealed a partially cystic tumor in the left kidney. FNA showed monotonous-appearing small round tumor cells with occasional rosette formation. The differential diagnoses include other primitive small round cell tumors. The tumor cells were immunoreactive for neuron specific enolase and O13 (CD99). A cytologic diagnosis of PNET was suggested and subsequently confirmed on histopathology.

CONCLUSION

To our knowledge, this is the first description of PNET of the kidney initially diagnosed by FNA. This nerve tumor must be included in the differential diagnosis of small cell malignant tumors of the kidney and adjacent organs.

Low-grade tubular-mucinous renal neoplasm with neuroendocrine differentiation: A histological, immunohistochemical and ultrastructural study

Low-grade tubular-mucinous renal neoplasm (LGTMRN) was recently established as a distinct carcinoma classification. A 70-year-old, female traffic accident victim underwent a detailed examination that disclosed a huge mass in the lower pole of the left kidney. The patient underwent a nephrectomy based on a diagnosis of renal tumor. Macroscopically, the tumor was well demarcated and a whitish color with focal hemorrhage. Histological examination showed that tumor cells proliferated through tubular, trabecular, and solid growth patterns in the mucinous background. Focally, foci of clear cells or the proliferation of spindle cells was also observed. Nuclei were generally round and uniform in size. No abnormal mitotic figures were identified. Immunohistochemically, tumor cells were diffusely positive for AE1/AE3, vimentin and chromogranin A, and focally positive for cytokeratin (CK) 18, CK19, Ulex europaeus agglutinin-1, epithelial membrane antigen, neuron-specific enolase (NSE), CD9 and CD57. Ultrastructurally, tumor cells contained a moderate number of mitochondria, rough endoplasmic reticulum and dense-core granules. No renin granules or glycogen were observed. Microvilli were focally seen. Our results render further evidence that LGTMRN is a distinct entity from the hitherto established renal neoplasms. Foci of clear cells and neuroendocrine differentiation should be added to the histological spectrum of LGTMRN.

Concomitant Loss of Mitochondria and the DNA Repair Protein hOGG1 in Clear Cell Carcinoma of the Kidney

The kidney is subjected to DNA oxidative damage from reactive oxygen species generated by free radicals and toxic metabolites, leading to formation of DNA base lesions. One such DNA lesion is 8-oxoguanine, which, if not sufficiently removed, is potentially mutagenic because it can cause G:C to T:A transversion in subsequent DNA replication. The human 8-oxoguanine DNA glycosylase 1 (hOGG1) gene on chromosome 3, a region (3p25-26) that shows frequent loss of heterozygosity in clear cell renal cell carcinoma (CC-RCC), encodes for a DNA repair enzyme capable of excision repair of 8-oxoguanine. Of the known isoforms of the hOGG1 enzyme (types Ia, Ib, Ic, Id, and II), only 1, Ia, is found in the nucleus, whereas the rest show a mitochondrial distribution. We investigated, by an immunohistochemical staining method, the expression of hOGG1 protein in 40 cases of CC-RCC, using archival formalin-fixed tissue. To localize the hOGG1 enzyme in normal and tumor tissue, immuno-staining against cytochrome c, a specific mitochondrial enzyme, was also performed. The results showed marked reduction in hOGG1 expression in the majority of tumors, with complete loss of staining seen in 26 (65%) and moderate and weak positive staining present in 9 (22.5%) and 5 (12.5%) of the cases, respectively. Strong hOGG1 protein expression was present in normal tubular epithelium, located in the mitochondria. The results correlated with the expression patterns of cytochrome c. The findings indicate that loss of hOGG1 expression may have a role in development or progression of CC-RCC.

Malignant rhabdoid tumor of the kidney in an adult: a case report and review of the literature

Malignant rhabdoid tumor of the kidney is an uncommon renal tumor in children. The tumor has aggressive behavior and a poor prognosis and is extremely rare in adults; only 3 cases of renal rhabdoid tumors have been reported in adults. We describe here the microscopic, immunohistochemical, and electron microscopic characteristics of another case in a 38-year-old woman. This case reinforces the importance of recognizing this entity in the adult population.

Influence of tissue preparation on the acoustic properties of tissue sections at high frequencies

The purpose of the present study was to clarify the influence of tissue preparation on the high-frequency acoustic properties by comparing the acoustic properties of the formalin-fixed, paraffin-embedded, deparaffinized sections and formalin-fixed, frozen sections for two types of fat-containing renal cancer and fat-free renal oncocytoma using a SAM. There was no significant difference for the sound speed among the clear cell, granular cell renal cancer and oncocytoma in either groups, but the attenuation constant was significantly higher for the frozen than for that of the paraffin section in fat-containing renal cancer. In fat-free oncocytoma, there was no significant difference for the attenuation constant in either group. The data suggest that the fat component, which had been eluted by paraffinization, is stored and the true acoustic properties of the tissue can be measured in frozen section.

Oncocytic angiomyolipoma of the kidney: a case report

We describe a case of oncocytic angiomyolipoma composed of polygonal eosinophilic cells, that shares many features with renal oncocytoma. It was composed of alveolar structures, with accumulation of foamy histiocyte-like cells surrounding large globules of acellular, nonfibrillary, densely eosinophilic basal membrane-like substance. Immunohistochemically, there was focal reactivity for HMB45 and negativity for the epithelial markers. Oncocytic angiomyolipoma lacks the atypical features of the recently described epithelioid variant of angiomyolipoma. None of the reported cases have been associated with tuberous sclerosis.