Recent advances in pediatric renal neoplasia

Imaging characterization of paediatric tumours with the neurotrophic tyrosine receptor kinase fusion transcript

OBJECTIVES

The neurotrophic tyrosine receptor kinase (NTRK) fusion transcript (FT) is a major genetic landmark of infantile fibrosarcoma (IFS) and cellular congenital mesoblastic nephroma (cCMN) but is also described in other tumours. The recent availability of NTRK-targeted drugs enhances the need for better identification. We aimed to describe the anatomic locations and imaging features of tumours with NTRK-FT in children.

CASE SERIES

Imaging characteristics of NTRK-FT tumours of 41 children (median age: 4 months; 63% <1 year old; range: 0-188) managed between 2001 and 2019 were retrospectively analysed. The tumours were located in the soft tissues (n = 24, including 19 IFS), kidneys (n = 9, including 8 cCMN), central nervous system (CNS) (n = 5), lung (n = 2), and bone (n = 1). The tumours were frequently deep-located (93%) and heterogeneous (71%) with necrotic (53%) or haemorrhagic components (29%). Although inconstant, enlarged intratumoural vessels were a recurrent finding (70%) with an irregular distribution (63%) in the most frequent anatomical locations.

CONCLUSION

Paediatric NTRK-FT tumours mainly occur in infants with very variable histotypes and locations. Rich and irregular intra-tumoural vascularization are recurrent findings.

ADVANCES IN KNOWLEDGE

Apart from IFS of soft tissues and cCMN of the kidneys, others NTRK-FT tumours locations have to be known, as CNS tumours. Better knowledge of the imaging characteristics may help guide the pathological and biological identification.

Therapeutic strategies and predictive models for Xp11.2 translocation/TFE3 gene fusion renal cell carcinoma in adults based on data of two Chinese medical centers

OBJECTIVE

This study aims to establish an effective predictive model for predicting Xp11.2 translocation/TFE3 gene fusion renal cell carcinoma (TFE3-RCC) and develop optimal therapeutic strategies.

METHODS

Data from 4961 patients diagnosed with renal cell carcinoma at two medical centers in China were retrospectively analyzed. A cohort of 1571 patients from Zhejiang Provincial People's Hospital (Ra cohort) was selected to construct the model. Another cohort of 1124 patients from the Second Affiliated Hospital of Zhejiang Chinese Medical University was used for external validation (the Ha cohort). All patients with TFE3-RCC in both cohorts were included in the Ta cohort for the prognostic analysis. Univariate and multivariate binary logistic regression analyses were performed to identify independent predictors of the predictive nomogram. The apparent performance of the model was validated. Decision curve analysis was also performed to assess the clinical utility of the developed model. Factors associated with progression and prognosis in the Ta cohort were analyzed using the log-rank method, and Cox regression analysis and Kaplan-Meier survival curves were used to describe the effects of factors on prognosis and progression.

RESULTS

Univariate and multivariate logistic regression analyses demonstrated that age, sex, BMI, smoking, eosinophils, and LDL were independent predictors of TFE3-RCC. Therefore, a predictive nomogram for TFE3-RCC, which had good discriminatory power (AUC = 0.796), was constructed. External validation (AUC = 0.806) also revealed good predictive ability. The calibration curves displayed good consistency between the predicted and observed incidences of TFE3-RCC. Invasion of regional lymph nodes, tyrosine kinase inhibitors, and surgical methods were independent factors associated with progression. Tyrosine kinase inhibitors are independent prognostic factors.

CONCLUSION

This study not only proposed a high-precision clinical prediction model composed of various variables for the early diagnosis of Xp11.2 translocation/TFE3 gene fusion renal cell carcinoma but also optimized therapeutic strategies through prognostic analysis.

Infantile Congenital Mesoblastic Nephroma Leading to Multi-Systemic End-Organ Disease

Congenital mesoblastic nephroma (CMN) is a rare infantile abdominal tumor that is highly curable with early surgical intervention. However, chronic, unrecognized tumor burden can cause significant compression of local vascular and solid structures, resulting in multi-systemic end-organ dysfunction. In this case report, we describe the effects of chronic abdominal compartment syndrome in an infant due to a solid renal tumor and its anesthetic implications.

Congenital mesoblastic nephroma: a single-centre series

BACKGROUND

Congenital mesoblastic nephroma is a rare disease. Treatment is surgical in the first instance. Chemotherapy has traditionally been thought not to have a role. Recent literature suggests a 50% mortality rate for recurrent/metastatic disease.

MATERIALS AND METHODS

This study is a retrospective case review of prospectively collected data. Demographics, histopathology, treatment, outcomes and follow up were reviewed.

RESULTS

Nine patients, 6 male and 3 female, were included. The median age at presentation was one month (range 0-7 months); follow-up was for a median of 21.5 months (range 16-79 months). Two patients had mixed and classical subtypes and the other five had the cellular subtype. Surgery was completed by an open procedure in eight patients and laparoscopically in one. There were three recurrences; two were local and one was pulmonary. Recurrences were treated with a combination of chemotherapy, radiotherapy and surgery. One patient with recurrent disease died from acute-on-chronic respiratory failure secondary to lung irradiation but was disease free. The other eight are disease free, alive and well with no sequelae at latest follow-up.

CONCLUSIONS

Surgery remains the mainstay of management with chemo- and radiotherapy reserved for unresectable tumours or adjuvant management of recurrent disease. Specimen-positive margins are not an indication for instituting chemotherapy. The tyrosine kinase pathway seems to be a potential target for future chemotherapeutic agents although it is too early to assess how that will impact on the management of congenital mesoblastic nephroma.

MiT family translocation renal cell carcinomas: A 15th anniversary update

Microphthalmia (MiT) family translocation renal cell carcinomas (RCCs) are a heterogeneous category of renal tumors which all express MiT transcription factors, typically from chromosomal translocation and rarely from gene amplification. This tumor family has two major subtypes [i.e., Xp11 translocation RCC and t(6;11) RCC] and several related neoplasms (i.e., TFEB amplification RCC and melanotic Xp11 translocation renal cancers). Increased understanding of the clinical, pathological, molecular and prognostic heterogeneity of these tumors, since their official recognition in 2004, provides the opportunity to identify prognostic biomarkers and to understand the reasons for tumor aggression. We will review the literature from the past 15 years and highlight the need for a greater understanding of the molecular mechanisms underpinning heterogeneous tumor behavior.

Primary Renal Sarcomas With BCOR-CCNB3 Gene Fusion: A Report of 2 Cases Showing Histologic Overlap With Clear Cell Sarcoma of Kidney, Suggesting Further Link Between BCOR-related Sarcomas of the Kidney and Soft Tissues

We report 2 primary renal sarcomas demonstrating BCOR-CCNB3 gene fusions that have recently been identified in undifferentiated round cell sarcomas of bone and soft tissue. These neoplasms occurred in male children aged 11 and 12 years, and both were cystic as a result of entrapment and dilatation of native renal tubules. Both cases were composed of variably cellular bland spindle cells with fine chromatin set in myxoid stroma and separated by a branching capillary vasculature. Both neoplasms demonstrated immunoreactivity for BCOR, cyclin D1, TLE1, and SATB2 in the spindle neoplastic cells and negativity in the prominent capillary vasculature. One case was extensively cystic and had hypocellular areas that simulated cystic nephroma; this neoplasm recurred 3 years later as a solid, highly cellular spindle cell sarcoma in the abdominal cavity. The morphology and immunoprofile of these renal neoplasms was compared with a control group of other sarcomas with BCOR genetic abnormalities, including clear cell sarcoma of the kidney (CCSK), infantile undifferentiated round cell sarcomas of soft tissue/primitive myxoid mesenchymal tumor of infancy, and bone/soft tissue sarcomas with BCOR-CCNB3 gene fusion; along with primary renal synovial sarcoma. Our findings show that the renal sarcomas with BCOR-CCNB3 gene fusion overlap with CCSK. These results are in keeping with a "BCOR-alteration family" of renal and extrarenal neoplasms which includes CCSK and undifferentiated round cell sarcomas of soft tissue/primitive myxoid mesenchymal tumor of infancy (which typically harbor BCOR internal tandem duplication), and BCOR-CCNB3 sarcomas, all of which are primarily driven by BCOR overexpression and have overlapping (but not identical) clinicopathologic features.

Congenital mesoblastic nephroma 50 years after its recognition: A narrative review

Congenital mesoblastic nephroma (CMN) is a rare pediatric renal tumor with low malignant potential that most commonly occurs early in infancy. Treatment strategies are based on the few published CMN series, while a significant number of CMN patients have been described in case reports. The aim of this narrative review was to create an up-to-date overview of the literature. Complete surgical removal is curative in most cases. The risk of treatment-related mortality (both surgery- and chemotherapy-related) is relatively high in the first weeks of life, indicating that these young patients deserve special attention with respect to timing and type of treatment.

[Solid pediatric tumors : A brief survey of the rarity cabinet]

Solid tumors in childhood are extremely rare entities, which are usually treated in specialized centers. Diagnosis and therapy are carried out according to a joint European protocol, whereby the pathological evaluation and therapy are carried out according to international guidelines. For the correct diagnosis and/or therapy of most tumors, analysis of specific genetic changes is mandatory; therefore, tumors have to be adequately sampled for parallel genetic analysis during the pathological work-up. A second opinion reference of the histopathological assessment is part of the international guidelines. Neuroblastomas, congenital mesoblastic nephromas and rhabdoid tumors are examples of solid tumors in childhood that are not restricted to one organ and occur exclusively during childhood.

Primary Ewing Sarcoma / Primitive Neuroectodermal Tumor of the Kidney: A Clinicopathologic Study of 23 Cases

Primary Ewing sarcoma / primitive neuroectodermal tumor (ES) of the kidney is a rare neoplasm with limited clinicopathologic data. We report 23 such cases with no history of ES elsewhere in the body. The patients included 13 male and 10 female, aged 8-70 years (mean, 31 years). The average tumor size was 11.7 cm (range, 5-20 cm). Microscopic analysis showed predominantly lobular growth (n = 14), with focal papillary (n = 3), alveolar (n = 1), and hemangiopericytoma-like (n = 1) patterns. Several tumors (n = 11) exhibited robust mitotic activity (>10 mitoses/10 high-power fields). Necrosis (n = 13) and lymphovascular invasion (n = 14) were common. Homer Wright rosettes (n = 6) and perivascular pseudorosettes (n = 1) were also identified. The tumors invaded the renal sinus or perinephric fat (n = 11), renal vein (n = 13), and adrenal gland (n = 2). Molecular and fluorescence in situ hybridization analysis showed rearrangement of EWSR1 gene (10/10), associated with EWSR1-FLI1 gene fusion (7/10). All patients with follow-up information (n = 18) had metastasis, commonly in the lungs (n = 12) and bone (n = 6). Twelve patients died of disease in a mean of 21 months; 6 patients were alive at a mean of 49 months after diagnosis. Primary kidney ES usually present at an advanced stage with extrarenal spread and metastasis. Although renal ES share histologic, immunohistochemical, and molecular features with their bone and soft tissue counterparts, they appear to be more aggressive tumors with poorer clinical outcome.

Xp11 Translocation Renal Cell Carcinoma Morphologically Mimicking Clear Cell–Papillary Renal Cell Carcinoma in an Adult Patient

Xp11 translocation renal cell carcinoma (RCC) is a relatively rare tumor mainly affecting children and adolescents. It shows significant morphological overlap with the 2 most common adult renal tumors, which are the clear cell (conventional) RCC and papillary RCC. We describe case of a young adult female who presented with right flank pain and abdominal mass. Radiological investigations showed features suggestive of renal cell carcinoma in the right kidney. Histopathological findings while suggestive of Xp11 carcinoma, showed significant overlap with the recently described entity clear cell papillary RCC. TFE3 immunohistochemistry confirmed the tumor to be Xp11 translocation RCC. The patient had an aggressive course with lymph node metastasis. In this report, we discuss differential diagnosis and the diagnostic challenges of Xp11 translocation RCC in adults.

Magnetic resonance imaging and computed tomography characteristics of renal cell carcinoma associated with Xp11.2 translocation/TFE3 gene fusion

PURPOSE

To characterize Xp11.2 translocation renal cell carcinoma (RCC) using magnetic resonance imaging (MRI) and computed tomography (CT).

METHODS

This study retrospectively collected the MRI and CT data of twelve patients with Xp11.2 translocation RCC confirmed by pathology. Nine cases underwent dynamic contrast-enhanced MRI (DCE-MRI) and 6 cases underwent CT, of which 3 cases underwent MRI and CT simultaneously. The MRI and CT findings were analyzed in regard to tumor position, size, hemorrhagic, cystic or necrotic components, calcification, tumor density, signal intensity and enhancement features.

RESULTS

The age of the 12 patients ranged from 13 to 46 years (mean age: 23 years). T2WI revealed heterogeneous intensity, hyper-intensity, and slight hypo-intensity in 6 cases, 2 cases, and 1 case, respectively. On DCE-MR images, mild, moderate, and marked rim enhancement of the tumor in the corticomedullary phase (CMP) were observed in 1, 6, and 2 cases, respectively. The tumor parenchyma showed iso-attenuation (n = 4) or slight hyper-attenuation (n = 1) compared to the normal renal cortex on non-contrast CT images. Imaging findings were suggestive of hemorrhage (n = 4) or necrosis (n = 8) in the tumors, and there was evidence of calcification in 8 cases by CT (n = 3) and pathology (n = 8). On dynamic contrast-enhanced CT images, 3 cases and 1 case manifested moderate and strong CMP enhancement, respectively. Nine tumors by MRI and 4 tumors by CT showed prolonged enhancement. Three neoplasms presented at stage I, 2 at stage II, 3 at stage III, and 4 at stage IV according the 2010 AJCC staging criteria.

CONCLUSIONS

XP11.2 translocation RCC should be considered when a child or young adult patient presents with a renal tumor with heterogeneous features such as hemorrhage, necrosis, cystic changes, and calcification on CT and MRI and/or is accompanied by metastatic evidence.

Renal Ewing tumors

BACKGROUND

Renal Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is extremely rare. Clinical symptoms are nonspecific presenting abdominal pain, palpable mass, and hematuria. Owing to advanced technology demonstrating the ES-specific EWS/ETS translocation, this differential diagnosis has become feasible.

PATIENTS AND METHODS

The German database of GPOH Ewing's sarcoma trials from 1980 to 2009 was searched for kidney as primary site. Twenty-four patients were identified and analyzed. The median time of observation was 3.71 years (range 0.27-8.75 years). Additionally, we carried out a Medline search for renal ES/PNET.

RESULTS

The median age was 24.9 years (range 11-60 years). In 37.5%, patients presented with primary metastases. Tumor thrombi in the adjacent renal vessels occurred in 56.2%. In 90.9%, rearrangements of t(11;22) were found. All patients received a combined chemotherapy according to the EURO-E.W.I.N.G.99 protocol. In accordance, local control consisted predominantly of combined modality surgery and radiation (47%). At 3 years, overall survival (OS) was 0.80 (SE = 0.09), and event-free survival (EFS) 0.66 (SE = 0.11).

CONCLUSIONS

ES/PNET should be considered in the differential diagnosis of renal tumors. Patients with renal ES/PNET respond to and benefit from conventional ES treatment according to ES study protocols. Therefore, an accurate diagnostic approach and a guideline-adapted therapy should be facilitated.

Persistent complete response after single-agent sunitinib treatment in a case of TFE translocation positive relapsed metastatic pediatric renal cell carcinoma

Forty percent of renal cell carcinomas (RCCs) in childhood are characterized by translocation involving transcription factor E3 (TFE3) family members. Here, we describe a case of TFE3-positive RCC in which metastatic relapse to the mediastinal lymph nodes and pulmonary nodules was treated with single-agent sunitinib, a multitargeted tyrosine inhibitor. Complete radiologic remission was achieved after only 3 courses of treatment, and surgical exploration of metastases failed to identify any residual viable disease. The published experience of sunitinib in TFE-RCC is limited, and prospective evaluation of its activity in a larger number of patients is warranted.

Melanotic xp11.2 neoplasm of the ovary: report of a unique case

We describe a primary ovarian neoplasm, occurring in a 15-year-old female patient, with morphologic, immunohistochemical, and molecular genetic features identical to those of the very rare tumors of the kidney previously described as "melanotic Xp11 translocation renal cancer." This represents, to the best of our knowledge, the first report of a melanotic Xp11 translocation-associated neoplasm arising outside of the kidney. We discuss the relationship of these rare tumors to neoplasms showing perivascular epithelioid cell differentiation, in particular those showing TFE3 rearrangements.

Renal primitive neuroectodermal tumor: does age at diagnosis impact outcomes?

Primitive neuroectodermal tumor (PNET) of the kidney is a rare and highly malignant neoplasm. The median age for renal PNET is 27 years but it can be seen also in a wide age range between 3 and 78 years. We performed a Medline search for the term renal PNET and identified 79 cases up till December of 2010. We report here a new case of renal PNET and a literature review for published data for evaluation of clinicopathological prognostic factors, with an emphasis on prognosis in two groups of adults and children-adolescents: 18 years of age or under and over 18 years.

Renal cell carcinoma in children and adolescents

Although rare in children and adolescents, renal cell carcinomas (RCCs) raise important questions concerning the best treatment approach and accurate pathologic classification. The differences emerging between childhood and adulthood RCC probably prevent any direct generalized application of therapies to children that are validated for adults. The translocation type of RCC, which forms a distinct category characterized by translocations involving Xp11.2 or, less frequently, 6p21, has recently emerged as the predominant type of RCC in children and adolescents, whereas it is rarely diagnosed in adults. This new finding emphasizes how important it is to prospectively classify RCCs in children with standardized 'modern' diagnoses. The standard cornerstone of therapy for RCC in children and adolescents remains radical nephrectomy. Nephron-sparing surgery is currently recommended in adults for selected small-volume tumors, but additional data are needed before this experience can be extensively transferred to the pediatric population. The therapeutic value of complete retroperitoneal lymph node dissection is still controversial, especially in patients without suspected nodal involvement, be they adults or children. The backbone of systemic therapies for adult RCC has recently been changed by the introduction of drugs designed to target tumor-related angiogenesis and signal transduction. It is worth noting that the largest clinical efficacy trials on targeted molecules have been conducted on clear-cell RCC. While targeted drugs have become the standard of care for adult metastatic RCC, there are currently no published reports on their role in children, and their use should be considered for patients with unresectable metastatic or advanced-stage RCC. On the other hand, the utility of targeted therapies in the adjuvant setting remains to be seen for both adults and children.

Unusual presentation of congenital infantile fibrosarcoma in seven infants with molecular-genetic analysis

Congenital infantile fibrosarcoma (CIFS) is a rare mesenchymal tumor that primarily presents in the soft tissue of the distal extremities and occasionally in unusual locations such as the lung and retroperitoneum. Herein, we report seven cases of unusual presentations of CIFS. These cases include three in the lungs, one in the retroperitoneum with cord compression, one in the posterior trunk, one in the heart, and one infratemporal involving the sphenoid bone. All tumors demonstrated CIFS's characteristic t(12;15)(p13;q25) and associated ETV6-NTRK3 gene fusion. One of the three lung cases was previously reported as primary bronchopulmonary fibrosarcoma (PBPF), but molecular analysis of the paraffin embedded tissue revealed the ETV6-NTRK3 gene fusion consistent with CIFS. We show that CIFS may occur in unusual sites including visceral locations, and we propose that neoplasms displaying the ETV6-NTRK3 gene fusion represent the visceral components of CIFS.

Xp11.2 Translocation Renal Cell Carcinomas Have a Poorer Prognosis Than Non-Xp11.2 Translocation Carcinomas in Children and Young Adults: A Meta-analysis

Objectives. Renal cell carcinomas (RCCs) in children and adolescents are much rarer than in adults. In this age group, Xp11.2 translocation RCCs were the most common subtype of pediatric RCCs. Information regarding the clinical behavior of pediatric RCCs remains controversial because of their relatively rare incidence. The authors aimed to perform a systematic review and meta-analysis to better define the biological features of pediatric RCCs. Methods. Eligible studies were identified through multiple search strategies. Studies were assessed for quality using the Jadad Quality Scale. Data were collected comparing overall survival (OS), disease-free survival (DFS), and stage in patients with TFE3 + pediatric RCCs and TFE3 − RCCs. Results. A total of 4 studies were included for meta-analysis, and pooled odds ratios (ORs) with 95% confidence interval (CI) were calculated. The meta-analysis outcomes showed that TFE3 + pediatric RCCs were significantly associated with poorer outcomes (OS and DFS) and a higher stage (III/IV) than TFE3 − RCCs (pooled ORs for each group: 4.59 [95% CI = 1.46-14.42] for OS; 5.79 [95% CI = 1.85-18.16] for DFS; and 5.89 [95% CI = 2.23-15.52] for stage). This result was also confirmed by OS and DFS curves ( P = .005 and P = .001). Conclusions. Xp11.2 translocation carcinomas appear to have a poorer prognosis than non-Xp11.2 translocation carcinomas in children and young adults.

Xp11.2 Translocation Renal Cell Carcinoma

Xp11.2 translocation renal cell carcinomas (RCCs), a recently recognized distinct subtype, are rare tumors predominantly reported in young patients. They comprise at least one-third of pediatric RCCs, and only few adult cases have been reported. They are characterized by various translocations involving chromosome Xp11.2, all resulting in gene fusions involving the transcription factor E3 (TFE3) gene. In recent years, at least 6 different Xp11.2 translocation RCCs have been identified and characterized at the molecular level. These include a distinctive RCC that bears a translocation with the identical chromosomal breakpoints (Xp11.2, 17q25) and identical resulting ASPL-TFE3 gene fusion as alveolar soft part sarcoma. They typically have papillary or nested architecture and are composed of cells with voluminous, clear, or eosinophilic cytoplasm. Their most distinctive immunohistochemical feature is nuclear labeling for TFE3 protein. Although only limited data are available so far, they are believed to be rather indolent, but there have been increasing, recent reports of an aggressive clinical course in adult cases. The consistent immunohistochemical staining for TFE3 in all RCC with unusual histology, regardless of patient age, is likely to expand the spectrum of Xp11.2 translocation RCC with respect to age, clinical behavior, and molecular abnormalities.

An adult Xp11.2 translocation renal carcinoma showing response to treatment with sunitinib

A rare variant of renal cell carcinoma (RCC) with a translocation involving Xp11.2 has become increasingly recognized as a separate entity in the 2004 World Health Organization (WHO) kidney carcinoma classification. These tumors predominantly affect children and young adults and tend to present with advanced stage disease. Although reported to be indolent in children, adult cases run a more aggressive course. Little is known about their natural history, prognosis and response to therapy. We report a case of Xp11 translocation renal cancer in a 33-year-old male patient who presented with widespread rapidly progressive metastatic disease involving extensive intra-thoracic lymph nodes, supra-clavicular, retroperitoneal lymph nodes, lung nodules, and peritoneal mass. He had failed to respond to treatment with high dose interleukin 2, but showed a significant clinical response to treatment with the multikinase inhibitor sunitinib. CT scan performed after 3 cycles (18 weeks) of therapy revealed more than 65% reduction of measurable disease by response evaluation criteria in solid tumors (RECIST) criteria, resolution of other assessable lesions, and a clinical benefit that lasted for over 13 months. But unfortunately, this was subsequently followed by a rapidly progressive course. The well-recognized clinical efficacy of multikinase inhibitors such as sunitinib and sorafenib is based on the outcomes in patients with clear cell histology. There is limited data on efficacy in non-clear cell RCC, but activity in translocation RCC has not been reported. To our knowledge, this is the first documented case of Xp11 translocation carcinoma to have demonstrated an objective durable response to sunitinib. It remains unclear how resistance to sunitinib develops, but the results to date support further evaluation of sunitinib in cases of translocation RCC.

Cellular mesoblastic nephroma (infantile renal fibrosarcoma): institutional review of the clinical, diagnostic imaging, and pathologic features of a distinctive neoplasm of infancy

BACKGROUND

Cellular mesoblastic nephroma has been associated with a more aggressive course than classic mesoblastic nephroma, including local recurrences and metastases.

OBJECTIVE

To define the clinicopathologic and imaging features distinguishing cellular from classic mesoblastic nephroma.

MATERIALS AND METHODS

Retrospective review of clinical charts and imaging studies of ten children with mesoblastic nephroma from 1996 to 2007 at a large children's hospital.

RESULTS

In six children the mesoblastic nephroma was pure cellular, in two mixed, and in two classic. The mean ages at diagnosis were 107 days for those with the cellular form, and 32 days for those with the classic form. Hypoechoic or low-attenuation regions representing necrosis or hemorrhage were found in all children with the cellular form and in none of those with the classic form. Hypertension was present in 70% and hypercalcemia in 20% of the children and resolved following nephrectomy. Two cellular tumors encased major abdominal vessels. Local recurrence and metastases occurred within 6 months of tumor resection in two children with the cellular form. Intraspinal extension and intratumoral pseudoaneurysm were seen in one child with the cellular form. The cellular tumors shared histopathologic features with infantile fibrosarcoma (IFS), and RT-PCR testing in two children with the cellular form revealed the t(12;15) ETV6-NTRK3 gene fusion common to IFS.

CONCLUSION

Distinct from the classic form, cellular mesoblastic nephroma is more heterogeneous in appearance on imaging, tends to be larger and present later in infancy, and can exhibit aggressive behavior including vascular encasement and metastasis. Intraspinal extension and intratumoral pseudoaneurysm are previously unreported findings encountered in our cellular mesoblastic nephroma series. The shared histopathology and translocation gene fusion support the concept of cellular mesoblastic nephroma as the renal form of IFS.

Uncommon and recently described renal carcinomas

Major consensus conferences held over a decade ago laid the foundations for the current (2004) WHO classification of renal carcinoma. Clear cell, papillary and chromophobe carcinomas account for 85-90% carcinomas seen in routine practice. The remaining 10-15% of carcinomas consist of rare sporadic and hereditary tumors, some of which had been long recognized, but many of which only emerged as distinct entities in the decade leading up to the WHO publication. Collecting-duct carcinoma is a rare, often lethal form of carcinoma. Medullary carcinoma associated with sickle cell trait, has emerged as a distinctive tumor showing some overlapping features with upper tract urothelial carcinoma. Mucinous tubular and spindle-cell carcinoma and tubulocystic carcinoma were earlier considered as patterns of low-grade collecting-duct carcinoma, but are now recognized as separate tumor entities. Carcinomas associated with somatic translocations of TFE3 and TFEB comprise a significant proportion of pediatric renal carcinomas. Oncocytoid renal carcinomas in neuroblastoma survivors was recognized as a unique tumor category in the WHO classification. Renal carcinoma associated with end-stage renal disease is now recognized as having distinct morphological patterns and behavior. In addition there is a group of rare recently described carcinomas, including clear cell papillary carcinoma, oncocytic papillary renal cell carcinoma, follicular renal carcinoma and leiomyomatous renal cell carcinoma. It behooves the surgical pathologist to not only be capable of diagnosing the common forms of renal cancer, but also to be aware of the rare types of renal carcinoma, many of which have emerged in recent years.

Xp11.2 translocation renal cell carcinoma occurring during pregnancy with a novel translocation involving chromosome 19: a case report with review of the literature

The recently recognized renal cell carcinomas (RCCs) associated with Xp11.2 translocations (TFE3 transcription factor gene fusions) are rare tumors predominantly reported in children. They comprise at least one-third of pediatric RCCs and only few adult cases have been reported. Here, we present a case of Xp11.2 translocation RCC in 26-year-old pregnant female. Her routine antenatal ultrasonography accidentally found a complex cystic right renal mass. Further radiologic studies revealed unilocular cyst with multiple mural nodules at inferior pole of right kidney, which was suspicious for RCC. She underwent right radical nephrectomy at 15 weeks gestation. Macroscopically, the cystic tumor was well encapsulated with multiple friable mural nodules on its inner surface. Microscopically, the tumor consisted of clear and eosinophilic/oncocytic voluminous cells arranged in papillary, trabecular, and nested/alveolar patterns. Occasional hyaline nodules and numerous psammoma bodies were present.

Immunohistochemically, the tumor showed strong nuclear positivity for TFE3. Epithelial membrane antigen, CD10, and E-cadherin were strongly positive. Cytokeratin AE1/AE3, cytokeratin CAM-5.2, calveolin, and parvalbumin were moderately positive. Cytokeratin 7, renal cell carcinoma antigen, and colloidal iron were focally weakly positive. BerEP4 and carbonic anhydrase IX were negative. Cytogenetically, the tumor harbored a novel variant translocation involving chromosomes X and 19, t(X;19)(p11.2;q13.1). Interphase FISH analysis performed on cultured and uncultured tumor cells using a dual-color break-apart DNA probe within the BCL3 gene on 19q13.3 was negative for the BCL3 gene rearrangement. She received no adjuvant therapy, delivered a normal term baby five months later, and is alive without evidence of disease 27 months after diagnosis and surgery. Unlike most recently reported Xp11.2 translocation RCCs in adult patients with aggressive clinical course, this adult case occurring during pregnancy with a novel translocation involving chromosome 19 followed an indolent clinical course.

Molecular Pathology of the Genitourinary Tract: Molecular Pathology of Kidney and Testes

With the advent of newer molecular technologies, our knowledge of cellular mechanisms with tumors of the kidney and testis has grown exponentially. Molecular technologies have led to better understanding of interplay between the von Hippel-Lindau gene and angiogenic cytokines in renal cancer and isochromosome 12p in testicular neoplasms. The result has been development of antiangiogenic-targeted therapy within recent years that has become the mainstay treatment for metastatic renal cell cancer. In the near future, classification and diagnosis of renal and testicular tumors through morphologic analysis will be supplemented by molecular information correlating to prognosis and targeted therapy. This article outlines tumor molecular pathology of the kidney and testis encompassing current genomic, epigenomic, and proteonomic findings.

Renal translocation carcinomas: clinicopathologic, immunohistochemical, and gene expression profiling analysis of 31 cases with a review of the literature

We report clinicopathologic features of a large series of renal translocation carcinomas from a multicentric study. Diagnosis was performed by cytogenetic examination of fresh material and/or by immunochemistry with antibodies directed against the C-terminal part of transcription factor E3 (TFE3) and native transcription factor EB (TFEB) proteins. Clinical data, follow-up, and histologic features were assessed. Antibodies against CK7, CD10, vimentin, epithelial membrane antigen, AE1-AE3, E-cadherin, alpha-methylacyl-coenzyme A racemase, melan A, and HMB45 were tested on tissue microarrays. Whole-genome microarray expression profiling was performed on 4 tumors. Twenty-nine cases were diagnosed as TFE3 and 2 as TFEB renal translocation carcinomas, including 13 males and 18 females, mean age 24.6 years. Two patients had a previous history of chemotherapy and 1 had a history of renal failure. Mean size of the tumor was 6.9 cm. Thirteen cases were > or = pT3 stage. Twelve cases were N+ or M+. Mean follow-up was 29.5 months. Three patients presented metastases and 5 have died. Mixed papillary and nested patterns with clear and/or eosinophilic cells represented the most consistent histologic appearance, with common foci of calcifications regardless of the type of translocation. Using a 30 mn incubation at room temperature, TFE3 immunostainings were positive in only 82% of our TFE3 translocation carcinomas. Both TFE3 and TFEB renal translocation carcinomas expressed CD10 and alpha-methylacyl-coenzyme A racemase in all cases. An expression of E-cadherin was observed in two-third of cases. Cytokeratins were expressed in less than one-third of cases. Melanocytic markers were expressed at least weakly in all cases except two. Unsupervised clustering on the basis of the gene expression profiling indicated a distinct subgroup of tumors. TRIM 63 glutathione S-transferase A1 and alanyl aminopeptidase are the main differentially expressed genes for this group of tumors. Our results suggest that these differentially expressed genes may serve as novel diagnostic or prognostic markers.

Renal tumours of childhood: an update

The role of the pathologist has been fundamental in the progress of the treatment of paediatric renal tumours. There are different philosophies in the treatment of these tumours, and there have been many recent advances in the areas of chemotherapy, identification of new entities, prognostic histological criteria following treatment and molecular prognostic and diagnostic features. This review discusses the different approaches of the different treatment protocols from Europe and North America, and reviews staging criteria, prognostic criteria and also the different tumour entities.

Sarcomas: genetics, signalling, and cellular origins. Part 1: The fellowship of TET

Sarcomas comprise some of the most aggressive solid tumours that, for the most part, respond poorly to chemo- and radiation therapy and are associated with a sombre prognosis when surgical removal cannot be performed or is incomplete. Partly because of their lower frequency, sarcomas have not been studied as intensively as carcinomas and haematopoietic malignancies, and the molecular mechanisms that underlie their pathogenesis are only beginning to be understood. Even more enigmatic is the identity of the primary cells from which these tumours originate. Over the past 25 years, however, several non-random chromosomal translocations have been found to be associated with defined sarcomas. Each of these translocations generates a fusion gene believed to be directly related to the pathogenesis of the sarcoma in which it is expressed. The corresponding fusion proteins provide a unique tool not only to study the process of sarcoma development, but also to identify cells that are permissive for their putative oncogenic properties. This is the first of two reviews that cover the mechanisms whereby specific fusion/mutant gene products participate in sarcoma development and the cellular context that may provide the necessary permissiveness for their expression and oncogenicity. Part 1 of the review focuses on sarcomas that express fusion genes containing TET gene family products, including EWSR1, TLS/FUS, and TAFII68. Part 2 (J Pathol 2007; DOI: 10.1002/path.2008) summarizes our current understanding of the genetic and cellular origins of sarcomas expressing fusion genes exclusive of TET family members; it also covers soft tissue malignancies harbouring specific mutations in RTK-encoding genes, the prototype of which are gastrointestinal stromal tumours (GIST).

Part II: Treatment of primary malignant non-Wilms' renal tumours in children

Renal-cell carcinoma, clear-cell sarcoma, (congenital) mesoblastic nephroma, rhabdoid tumour, and renal medullary carcinoma form a heterogeneous group of childhood renal malignancies known as non-Wilms' tumours. Progress has been slow in improving the management of these tumours to decrease morbidity and increase survival. However, greater cooperation between national and international centres should engender specialisation, and an increased knowledge of the molecular biology of these tumours will inevitably lead to substantial progress over the next decade. This review is the second of two parts: the first part provided an updated review of the clinical presentation, imaging, and pathology of non-Wilms' tumours and this second part provides an updated review of the treatment of these tumours.

Part I: Primary malignant non-Wilms' renal tumours in children

Non-Wilms' tumours form a small heterogeneous group of clinically significant renal malignancies in children, including renal-cell carcinoma, clear-cell sarcoma, (congenital) mesoblastic nephroma, rhabdoid tumour, and renal medullary carcinoma. Good progress has been made in the assessment of these tumours, which has led to a greater understanding of the molecular changes that occur in their development. This review is the first of two parts, and provides an updated review of the clinical presentation, imaging, and pathology of these tumours.

Pediatric Renal Cell Carcinoma with Oncocytoid Features Occurring in a Child After Chemotherapy for Cardiac Leiomyosarcoma

We report a case of renal cell carcinoma (RCC) with extensive oncocytoid features developing in a 12-year-old African-American boy after chemotherapy for cardiac leiomyosarcoma at 3 months of age. The tumor showed histopathologic features similar to those previously reported in RCC after chemotherapy for neuroblastoma and now considered a specific entity in the World Health Organization classification of renal tumors as "RCC associated with neuroblastoma." Our report expands the spectrum of tumors (beyond neuroblastoma) in which RCCs with such an appearance can arise in the pediatric age group after chemotherapy.

Xp11 translocation carcinoma of the kidney presenting with multilocular cystic renal cell carcinoma-like features

Reported is the case of a 17-year-old girl with a multicystic tumor in the middle of the right kidney. Partial nephrectomy revealed an epithelial neoplasm with multilocular cystic renal cell carcinoma pattern. The cells exhibited strong nuclear reactivity for TFE3 protein and supported the diagnosis of Xp11 translocation carcinoma of the kidney. A similar case has not been found in the literature. The example emphasizes the high index of suspicion needed for an accurate diagnosis of renal carcinomas.

An update on the management of Wilms' tumour

AIMS

To review the management of Wilms' tumour.

METHODS

A search of the literature was performed using the PubMed database (1966 to May 2006) with the search terms 'Wilms' and either 'tumour/tumor' or 'cancer' or 'carcinoma'. This was augmented by manual searches of publications.

FINDINGS

The success of clinical trials in Wilms' tumour patients over the past 30 years has led to an overall survival of 85% and the introduction of less aggressive chemotherapeutic regimes for patients. Large randomised controlled trials have been published on the management of Wilms' tumour by various collaborative groups, including the National Wilms' Tumour Study Group (NWTSG) in North America and the Société Internationale d'Oncologie Pédiatrique (SIOP) plus the United Kingdom Children's Cancer Study Group (UKCCSG) in Europe.

CONCLUSIONS

Controversy exists as to the best approach to the management of these children with regard to neoadjuvant chemotherapy. Challenges remain in the identification of histological and molecular risk factors for the stratification of treatment intensity.