Renal-cell carcinoma in children: a different disorder from its adult counterpart?

Renal cancer: cytogenetic and molecular genetic aspects

To date, much progress has been made in the fields of cytogenetics and molecular genetics of renal tumors. The previous and recent findings have delineated the characteristics of the various tumors, particularly the cytogenetic and molecular differences that exist between papillary and nonpapillary clear cell renal cell carcinomas (RCCs). At the same time, new cytogenetic subtypes have emerged [e.g., t(X;1)] in subtypes of RCC, while in others (e.g., Wilms tumors) several new cytogenetic abnormalities and consequent molecular involvement have been found. In addition to Wilms tumor, papillary RCC, and clear-cell RCC, cytogenetic and fluorescence in situ hybridization analyses have been performed on several other tumors of the kidney, including chromophobic carcinoma, metanephric adenoma, collecting duct carcinoma, transitional cell carcinoma, congenital mesoblastic nephroma, and malignant rhabdoid tumors of the kidney. This review is therefore intended to present a concise update on the cytogenetic and molecular data on renal tumors, focusing mainly on the clinical usefulness of the findings reported in the literature.

Renal cell carcinoma as a secondary malignancy after treatment of acute promyelocytic leukemia

Numerous children have been treated successfully for cancer and are surviving into adulthood. As this population has aged, an increasing number of secondary malignancies has emerged. Renal cell carcinoma (RCC) is a rare tumor in childhood and has not been documented previously to occur after treatment of acute promyelocytic leukemia (APL). This report describes the clinical course of APL treated in a child in whom RCC subsequently developed during adolescence approximately 5 years after therapy.

Impairment of MAD2B-PRCC interaction in mitotic checkpoint defective t(X;1)-positive renal cell carcinomas

The papillary renal cell carcinoma (RCC)-associated (X;1)(p11;q21) translocation fuses the genes PRCC and TFE3 and leads to cancer by an unknown molecular mechanism. We here demonstrate that the mitotic checkpoint protein MAD2B interacts with PRCC. The PRCCTFE3 fusion protein retains the MAD2B interaction domain, but this interaction is impaired. In addition, we show that two t(X;1)-positive RCC tumor cell lines are defective in their mitotic checkpoint. Transfection of PRCCTFE3, but not the reciprocal product TFE3PRCC, disrupts the mitotic checkpoint in human embryonic kidney cells. Our results suggest a dominant-negative effect of the PRCCTFE3 fusion gene leading to a mitotic checkpoint defect as an early event in papillary RCCs.

111 renal neoplasms of childhood: a clinicopathologic study

PURPOSE

The aim of this study was to perform a clinicopathologic evaluation of a single pediatric institution renal tumor series. Most patients were treated within the frame of 3 consecutive SIOP trials, which included preoperative chemotherapy as their main feature.

METHODS

Medical records and diagnoses of 111 patients were reviewed. The association of pathologic features with outcome was investigated by means of the Kaplan-Meier method, the Cox model, and a logistic multivariate analysis. Comparison among different trial results was carried out.

RESULTS

In 98 patients (88%), nephroblastoma was diagnosed, followed by 6 adult-type renal tumors, 3 cystic nephromas, 2 mesoblastic nephromas, and 2 clear cell sarcomas. For nephroblastoma, a statistically significant correlation between grade and both disease-free survival rate and 5-year survival rate, and between stage and overall survival rate was shown. Lymph node involvement, local relapse, nephrogenic rests, and older age at presentation appeared to be less important prognostic factors. Tumor spillage was very sensitive to chemo or radiotherapy. No significant difference in outcome was observed among different trials.

CONCLUSIONS

Wilms' tumor was the most frequent neoplasm and resulted in a 5-year cure rate of 90%. Clinical course was influenced mainly by diffuse anaplasia and, to a minor extent, by lymph node involvement. Because some tumors followed an unpredictable course, it is likely that also other biological factors played a significant role.

Primary renal neoplasms with the ASPL-TFE3 gene fusion of alveolar soft part sarcoma: a distinctive tumor entity previously included among renal cell carcinomas of children and adolescents

The unbalanced translocation, der(17)t(X;17)(p11.2;q25), is characteristic of alveolar soft part sarcoma (ASPS). We have recently shown that this translocation fuses the TFE3 transcription factor gene at Xp11.2 to ASPL, a novel gene at 17q25. We describe herein eight morphologically distinctive renal tumors occurring in young people that bear the identical ASPL-TFE3 fusion transcript as ASPS, with the distinction that the t(X;17) translocation is cytogenetically balanced in these renal tumors. A relationship between these renal tumors and ASPS was initially suggested by the cytogenetic finding of a balanced t(X;17)(p11.2;q25) in two of the cases, and the ASPL-TFE3 fusion transcripts were then confirmed by reverse transcriptase-polymerase chain reaction. The morphology of these eight ASPL-TFE3 fusion-positive renal tumors, although overlapping in some aspects that of classic ASPS, more closely resembles renal cell carcinoma (RCC), which was the a priori diagnosis in all cases. These tumors demonstrate nested and pseudopapillary patterns of growth, psammomatous calcifications, and epithelioid cells with abundant clear cytoplasm and well-defined cell borders. By immunohistochemistry, four tumors were negative for all epithelial markers tested, whereas four were focally positive for cytokeratin and two were reactive for epithelial membrane antigen (EMA) (one diffusely, one focally). Electron microscopy of six tumors demonstrated a combination of ASPS-like features (dense granules in four cases, rhomboid crystals in two cases) and epithelial features (cell junctions in six cases, microvilli and true glandular lumens in three cases). Overall, although seven of eight tumors demonstrated at least focal epithelial features by electron microscopy or immunohistochemistry, the degree and extent of epithelial differentiation was notably less than expected for typical RCC. We confirmed the balanced nature of the t(X;17) translocation by fluorescence in situ hybridization in all seven renal tumors thus analyzed, which contrasts sharply with the unbalanced nature of the translocation in ASPS. In summary, a subset of tumors previously considered to be RCC in young people are in fact genetically related to ASPS, although their distinctive morphological and genetic features justify their classification as a distinctive neoplastic entity. Finally, the finding of distinctive tumors being associated with balanced and unbalanced forms of the same translocation is to our knowledge, unprecedented.

Transformation capacities of the papillary renal cell carcinoma-associated PRCCTFE3 and TFE3PRCC fusion genes

A recurrent chromosomal abnormality associated with a subset of papillary renal cell carcinomas is t(X;1)(p11;q21). This translocation leads to the formation of two fusion genes, TFE3PRCC and the reciprocal product PRCCTFE3. Both fusion genes are expressed in t(X;1)-positive renal cell carcinomas and contain major parts of the coding regions of the parental transcription factor PRCC and TFE3 genes, respectively. To find out whether these fusion genes possess transforming capacity, we transfected NIH3T3 and rat-1 cells with the fusion products, either separately or combined. When using soft agar assays, we observed colony formation in all cases. NIH3T3 cells transfected with PRCCTFE3 or PRCCTFE3 together with TFE3PRCC yielded the highest colony forming capacities. Examination of other characteristics associated with malignant transformation, i.e., growth under low-serum conditions and formation of tumors in athymic nude mice, revealed that cells transfected with PRCCTFE3 exhibited all these transformation-associated characteristics. Upon transfection of the fusion products into conditionally immortalized kidney cells, derived from the proximal tubules of an H-2Kb-tsA58 transgenic mouse, and consecutive incubation under non-permissive conditions, growth arrest was observed, followed by differentiation except for those cells transfected with PRCCTFE3. Therefore, we conclude that PRCCTFE3 may be the t(X;1)-associated fusion product that is most critical for the development of papillary renal cell carcinomas.

Treatment of childhood renal cell carcinoma with lymph node metastasis: two cases and a review of literature

Standard treatment for renal cell carcinoma (RCC) is radical nephrectomy with lymph node dissection. Stages I and II have encouraging prognoses, but Stage III with regional lymph node metastasis can be unfavorable. Adjuvant therapy for pediatric patients with advanced RCC with lymph node involvement or metastatic lesion has not been defined. Advanced pediatric RCC is reported in two patients (boys, aged 6 and 9 years: Stage IIIs, Robson; Stage III and IV, pTNM classification) treated by nephrectomy and lymph node dissection followed by postoperative interferon-alpha (IFN), that can be used as an adjuvant therapy with side effects such as fever, bone marrow suppression, or decreased liver function. One is doing well for 7 years, another is suffered from lung metastases at 3 years after surgery. Although immunotherapy is expected to improve survival in pediatric patients with advanced RCC, surgical resection of renal and metastatic tumors remains the standard treatment.

Non-Wilms' renal tumors in children

Renal tumors other than Wilms' tumors are infrequent in childhood. Wilms' tumors account for 6% to 7% of childhood cancer, whereas the remaining renal tumors account for less than 1%. The most common non-Wilms' tumors are clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, renal cell carcinoma, mesoblastic nephroma, and multilocular cystic nephroma. Collectively, these tumors account for less than 10% of the primary renal neoplasms in childhood.

Translocation (X;1) associated with a nonpapillary carcinoma in a young woman: a new definition for an Xp11.2 RCC subtype

We report a translocation (X;1)(p11.2;q21) associated with a nontubulopapillary renal cell carcinoma in a 23-year-old woman. To our knowledge this the first report of such an association. A review of the previously published cases of renal cell carcinoma with t(X;1) and its cytogenetic variants with Xp11.2 anomalies is included. The role of this karyotype abnormality as a clinical marker is discussed. The Xp11.2 abnormality could be a primary abnormality characterizing a particular type of RCC appearing in children and young adults of both sexes and in which the histological aspect is not specific.