Nephrogenic rests, nephroblastomatosis, and the pathogenesis of Wilms' tumor

A new classification and terminology is proposed for precursor lesions of Wilms' tumor (WT), based upon morphology and natural history. The generic term nephrogenic rest (NR) is used for all WT precursors. Two major categories of NR are recognized: perilobar (PLNR) and intralobar (ILNR). Nephroblastomatosis signifies the presence of multiple or diffuse NRs. Nephroblastomatosis can be classified into four categories: (a) perilobar (PLNR only); (b) intralobar (ILNR only; (c) combined (PLNR and ILNR); and (d) universal. The individual rests can be subdivided into (a) nascent or dormant NRs; (b) maturing or sclerosing NRs; (c) hyperplastic NRs; and (d) neoplastic NRs. Of 282 evaluable unilateral WT specimens, 28.4% were definitely rest-positive, and an additional 12.4% were probably positive, with equal prevalence of PLNRs and ILNRs. Median age at diagnosis of WT was 36 months with PLNRs, 16 months with ILNRs, and 12 months if both types were present. PLNRs were strongly associated with synchronous bilateral WTs, and ILNRs with metachronous contralateral WTs. ILNRs were associated with aniridia and Drash syndrome, whereas PLNRs were more commonly found with hemihypertrophy and/or Beckwith-Wiedemann syndrome. The delineation of two distinct categories of WT precursors suggests pathogenetic heterogeneity for WTs. The biological and clinical implications of NRs are considered in the context of this classification.     

Precursor lesions of Wilms tumor: Clinical and biological implications

Nephrogenic rests (NR) are persistent embryonal remnants in the kidney that are apparent precursors of Wilms tumor (WT). Nephroblastomatosis (Nbl) denotes multiple or diffuse NR. Two major categories of NR have been recognized to date, perilobar (PLNR) and intralobar (ILNR). A dynamic classification of NR according to their recognized developmental fates is presented. Dormancy, maturation, involution, hyperplastic overgrowth, and neoplastic induction are the common fates of NR. Hyperplastic NR are far more common than formerly recognized, and are frequently confused with WT, especially in cases of multicentric and bilateral tumors. Biopsy is of limited value in distinguishing hyperplastic NR from WT, and the use of surgery in cases of Nbl requires careful consideration, as its role can in many cases be reduced or supplanted due to the effectiveness of modern imaging techniques and chemotherapy. An understanding of the natural history of NR and Nbl is essential for rational patient care decisions, and is important for understanding the molecular biology of WT. © 1993 Wiley-Liss, Inc.     

Wilms tumors and their precursors: Radiological diagnosis versus histology

The radiological distinction of Wilms tumor (WT) nodules from nephrogenic rests (NR) in patients with multifocal unilateral WT or bilateral disease is challenging. The study aims to compare the radiology assessment of kidney nodules with their final histology in 48 patients. The final histology of 118 nodules corresponded to the initial radiological diagnosis while 40 (25%) nodules were misdiagnosed, 20 being initially diagnosed WT on imaging were proved to be NR at histology. The size of nodules at diagnosis might help to distinguish WT from NR before surgery. Homogeneity did not seem to be a key feature.     

Ossifying Renal Tumor of Infancy: A Clinicopathologic Study of Nine Cases

We studied nine ossifying renal tumors of infancy (ORTI), including all five previously reported cases. There were eight boys and one girl ranging in age from 6 days to 14 months. Cross hematuria was the presenting sign in all nine patients. Eight tumors arose in the left kidney and six in the upper pole. All seven patients with follow-up information were free of recurrence. All lesions were attached to a renal papilla and presented mainly within the calyceal lumen. Two resembled staghorn calculiclinically. All tumors contained varying proportions of osteoid, osteoblastic cells, and spindle cells. The spindle cell component had features strongly suggesting that they represented hyperplastic intralobar nephrogenic rests (ILNR). The proportion of osteoid and degree of osseous maturation increased with increasing age of the patient. ORTI is a distinctive clinicopathologic entity, possibly representing a distinctive interaction between ILNR in the renal papilla with distal collecting duct or urothelial cells in the developing kidney.     

Epidemiology of Wilms tumor

Wilms tumor affects approximately one child per 10,000 worldwide before the age of 15 years. Incidence rates appear to be slightly elevated for U.S. and African Blacks in comparison to Whites, but are only half as great among Asians. Several case-control studies have suggested that paternal occupational or maternal hormonal exposures during pregnancy may increase the risk of Wilms tumor, but small numbers of subjects and inconsistencies in the patterns of exposures do not permit firm conclusions to be drawn. It is unlikely that such environmental exposures play a major role in the etiology of Wilms tumor. The median age-at-onset of Wilms tumor is 38 months in the U.S. National Wilms Tumor Study series, with cases in girls occurring on average 6 months later than in boys. Patients with bilateral tumors, aniridia, cryptorchism/hypospadias, Beck-with-Wiedemann syndrome, or intralobar nephrogenic rests tend to be diagnosed much younger than average (median 17–27 months). Those with familial disease or multicentric tumors have intermediate age-at-onset distributions, while those with perilo-bar nephrogenic rests are diagnosed at older ages. The epidemiologic features suggest that somatic mosaicism, rather than a germ-line mutation, may be responsible for some of the bilateral and multicentric cases. © 1993 Wiley-Liss, Inc.     

Management of Wilms tumors in Drash and Frasier syndromes

Background

Children with WT1 gene‐related disorders such as Denys–Drash syndrome (DDS) and Frasier syndrome (FS) are at increased risk of Wilms tumor and end‐stage renal disease. We investigated whether Wilms tumors in these patients displayed a specific phenotype or behavior and whether nephron‐sparing surgery was beneficial.

Procedure

We retrospectively studied all patients with DDS, FS, or other WT1 mutations treated at our institutions between 1980 and 2007.

Results

We identified 20 patients, of whom 18 had benign or malignant tumors. Wilms tumors occurred in 15 patients, being unilateral in 10 and bilateral in 5 (20 tumors). Median age at Wilms tumor diagnosis was 9 months. No patients had metastases. According to the International Society of Pediatric Oncology Working Classification, there were 19 intermediate‐risk tumors and one high‐risk tumor; no tumor was anaplastic. In patients with nephropathy who underwent unilateral nephrectomy for Wilms tumor or nephron‐sparing surgery for bilateral Wilms tumor, mean time to dialysis was 11 or 9 months, respectively. Other tumors included three gonadoblastomas (in two patients), one retroperitoneal soft‐tissue tumor, and one transitional cell papilloma of the bladder. Two patients, both with stage I Wilms tumor, died from end‐stage renal disease‐related complications. The median follow‐up time for the 18 survivors was 136 months (range, 17–224 months).

Conclusion

Most Wilms tumors in children with WT1‐related disorders were early‐stage and intermediate‐risk tumors, with a young age at diagnosis. In patients without end‐stage renal disease, nephron‐sparing surgery should be considered for delaying the onset of renal failure. Pediatr Blood Cancer 2009;52:55–59. © 2008 Wiley‐Liss, Inc.     

Treatment of children with stage IV favorable histology Wilms tumor: A report from the National Wilms Tumor Study Group

The purpose of this study was to evaluate the effect of the sequential addition of doxorubicin and cyclophosphamide to the combination of vincristine and actinomycin D on the relapse-free survival of children with stage IV/favorable histology Wilms tumor. We reviewed the clinical courses of all randomized patients from National Wilms Tumor Study (NWTS)-2 and 3 with stage IV/favorable histology (FH) Wilms tumor. We determined the four-year relapse-free survival percentage for patients treated on NWTS-2 with the combination of vincristine (VCR) and actinomycin D (AMD) with (regimen D) or without (regimen C) doxorubicin (DOX), and for patients treated on NWTS-3 with the combination of VCR + AMD + DOX with (regimen J) or without (regimen DD-RT) cyclophosphamide (CTX). All children received whole lung radiation therapy. The four-year relapse-free survival percentage for children with stage IV/FH Wilms tumor treated with regimen C was 53.3%, compared to 57.7% for those treated with regimen D (P = 0.63). The four-year relapse-free survival percentage for children with stage IV/FH Wilms tumor treated with regimen DD-RT was 79.0%, compared to 80.9% for those treated on regimen J (P = 0.79). The four-year relapse-free survival for children with lung metastases only treated with regimen D on NWTS-2 was significantly lower than that of children treated with the related regimen DD-RT on NWTS-3 (P = 0.03). We conclude that the addition of doxorubicin to the combination of vincristine and actinomycin D and pulmonary irradiation did not clearly improve the four-year relapse-free survival percentage of children with stage IV/FH Wilms tumor, although the benefit may have been masked by the greater frequency of death due to toxicity in NWTS-2. There was no evidence that the addition of CTX to the three-drug treatment regimen improved the four-year relapse-free survival percentage of children with stage IV/FH Wilms tumor. The data with only two drugs derived from NWTS-2 suggest that there is a population of children with stage IV/FH Wilms tumor who can be successfully treated without an anthracycline. The goal of future research will be to identify this subgroup at the time of initial diagnosis. © 1996 Wiley-Liss, Inc.     

Teratoid Wilms' tumor, an important variant of nephroblastoma

PurposeThe teratoid histologic variant of Wilms’ tumor is rare, with only 15 prior reported cases. We review these and report an additional case in which a cytogenetic abnormality was identified that has not previously been reported in a teratoid Wilms’ tumor.Materials and methodsA medline search revealed 15 previously reported cases of the teratoid variant of Wilms’ tumor. We summarized the characteristics of these cases with attention to radiologic appearance, stage, laterality, histology, response to chemotherapy and outcomes.ResultsCharacteristic radiologic features suggesting teratoid Wilms’ tumor were calcific densities and stippling, or areas of attenuation indicating adipose tissue. The majority of teratoid Wilms’ tumor patients had a high tumor stage at presentation (50% stage III or greater). The incidence of bilateral tumors was 38%. Chemotherapy was administered in nine cases and in only one (11%) was there a cytoreductive response. Four deaths (25%) occurred amongst these patients.ConclusionsTeratoid Wilms’ tumors appear to present with a high stage, increased incidence of bilaterality and have a high mortality rate. Treatment strategies should focus on total surgical extirpation, including metastatic sites when feasible, due to this entity's limited response to chemotherapy.     

肾母细胞瘤诊治10年回顾

目的 对10年中收治的小儿肾母细胞瘤的发病特点和诊治进行回顾分析,讨论影响肾母细胞瘤治疗和预后的因素.方法 统计10年期间69例肾母细胞瘤患儿的临床资料,包括患儿性别,发病年龄,临床表现和分期,病理分型和治疗手段,并将患儿分别以临床分期和病理分型进行分层,用Kaplan-Meier进行单因素生存分析.结果平均发病年龄(3.25±2.78)岁,发现腹部包块为主要起病症状,其中Ⅰ期18例,Ⅱ期25例,Ⅲ20例,Ⅳ期6例.治疗手段为患肾切除,NWTSG的化疗方案和有限病例的放疗.随访时间4～123个月,平均生存时间(41±30.9)个月.生存率:总体生存率78.2%,其中Ⅰ期患儿100%,Ⅱ期患儿76%,Ⅲ期患儿70%,Ⅳ期患儿50%.Kaplan-Meier生存分析表明,Ⅰ期、Ⅱ期、Ⅲ期三组患儿的生存时间差别无统计学意义,但明显高于Ⅳ期组患儿(LogRank法,P=0.04).预后良好组织类型(FH)组生存率为86.9%,其中Ⅰ期为100%,Ⅱ期93.3%,Ⅲ期72.7%,Ⅳ期50%;预后不良组织类型(UH)组总体生存率为65.2%,Kaplan-Meier生存分析生存表明,二组的生存时间具有显著性差异(Log Rank法,P=0.004).结论 临床分期,病理类型和治疗手段是影响肾母细胞瘤患儿预后的重要因素.     

Anaplastic histology Wilms’ tumors registered to the Japan Wilms’ Tumor Study Group are less aggressive than that in the National Wilms’ Tumor Study 5

Purpose

To evaluate the clinical features and treatment results of anaplastic histology (AH) Wilms’ tumor (WT) patients registered in the Japan Wilms’ Tumor Study (JWiTS) group to elucidate the clinical characteristics of AH in the Japanese population.

Patients and methods

Of 344 WT patients who were enrolled in JWiTS between 1995 and 2013, 17 had AH. Treatment using the JWiTS protocols was similar to the fifth National Wilms’ Tumor Study 5 (NWTS-5) protocols. Clinical characteristics and mutation status of TP53 gene were evaluated and compared with those in NWST-5 study.

Results

AH incidences in JWiTS were 4.9 %, lower than that in NWTS-5. Seven tumors had focal AH and 10 had diffuse AH. Clinical stages of AH patients were stage I in seven, stage II in three, stage III in five, stage IV in one and unknown in one. Four-year event-free survival and overall survival rates were 90.9 and 86.7 %, respectively. Two patients with diffuse AH and none with focal AH had TP53 mutation.

Conclusion

Japanese patients presented with higher incidence, earlier stages and may have better outcomes than American patients, indicating a possible biological heterogeneity of AH WT. Further analysis is necessary to elucidate the different characteristic of AH WT between Japanese and American populations.

     

Response without shrinkage in bilateral Wilms tumor: significance of rhabdomyomatous histology

PURPOSE: To test the hypothesis that poor response to chemotherapy in patients with bilateral Wilms tumor may be associated with the appearance of rhabdomyomatous histology, suggesting a differentiation response. METHODS: Twenty-six patients with bilateral Wilms tumor were treated at the authors' hospital between 1985 and 1995. Radiologic response to presurgical chemotherapy was assessed, and postsurgery histology was reviewed. RESULTS: There was a significant association between rhabdomyomatous differentiation in postchemotherapy surgical specimens and poor radiologic response. Poor response did not, however, necessarily mean poor outcome: of 11 patients with rhabdomyomatous differentiation, 7 are alive and disease-free, 2 died of complications, and only 2 died of uncontrolled Wilms tumor. CONCLUSIONS: Rhabdomyomatous differentiation in postchemotherapy bilateral Wilms tumor is associated with poor radiologic response. This observation may indicate a differentiation response rather than an absolute failure of response to chemotherapy. Clinical measures other than tumor volume are needed to distinguish between tumors that respond to chemotherapy but do not shrink, and those that genuinely do not respond.     

Results of the SIOP 93-01/GPOH trial and study for the treatment of patients with unilateral nonmetastatic Wilms Tumor

BACKGROUND: The treatment of Wilms Tumor is integrated into clinical trials since the 1970's. In contrast to the National Wilms Tumor Study Group (NWTSG) the SIOP trials and studies largely focus on the issue of preoperative therapy to facilitate surgery of a shrunken tumor and to treat metastasis as early as possible. PATIENTS AND METHODS: In the SIOP 93-01/GPOH trial and study 1 020 patients with a newly diagnosed renal tumor were registered. 847 of them had a histological proven Wilms Tumor, of whom 637 were unilateral localized, and 173 tumors had an other histology [40 congenital mesoblastic nephroma (CMN), 51 clear cell sarcoma (CCSK), 24 rhabdoid tumor (RTK) and 58 other tumors]. Preoperative chemotherapy in benign tumors was given to 1.3 % of the patients. The main objective of the trial was the randomized question, if the postoperative two drug chemotherapy for stage I in intermediate risk or anaplasia can be reduced from conventional 3 courses to an experimental 1 course without loss of efficacy. RESULTS: 519 patients with unilateral nonmetastatic Wilms did receive preoperative chemotherapy. The histology in this group of patients was of intermediate risk in 469 (90 %) patients, 14 (3 %) tumors were low risk and 36 (7 %) high risk. The stage distribution of the tumors was stage I in 315 (61 %), stage II N- in 126 (24 %), stage II N+ in 25 (5 %) and stage III in 36 (7 %) patients. In 17 (3 %) patients the tumor stage remained unclear. Tumor volume was measured in 487 patients before and in 402 after preoperative chemotherapy. The median tumor volume did shrink from 353 to 126 ml. The amount of volume reduction depends on the histological subtype. The event free survival (EFS) after 5 years was 91 % for all patients with unilateral Wilms tumor without distant metastasis. Randomisation was done in 43.7 % for stage I patients and there was no difference in EFS for both treatment arms (90 versus 91 %). The EFS is identical for patients with stage I and II N- (0.92), as well as for stage II N+ and III (0.82). The tumor volume after chemotherapy is a prognostic factor for intermediate risk tumors with the exception of epithelial and stromal predominant tumors. These two subtypes often present as large tumors, they do not shrink during preoperative chemotherapy but they still have an excellent prognosis. On the other hand the prognosis of patients with blastemal predominant subtype after preoperative chemotherapy is worse than in any other patient group of intermediate risk tumors. There are less blastemal predominant tumors compared to primary surgery, but they are chemotherapeutic resistant selected by the preoperative chemotherapy. CONCLUSION: Patients with unilateral Wilms tumor without metastasis have an excellent prognosis. The post-operative chemotherapy in stage I can be reduced to 4 weeks without worsening treatment outcome. The reduction of the tumor volume could be identified as a helpful marker for stratification of post-operative treatment. Post-chemotherapy blastemal predominant subtype of Wilms tumor has to be classified as high risk tumor. Focal anaplasia has a better prognosis than diffuse anaplasia and will be classified as intermediate risk tumor.     

Severe intrarenal fibrosis,infundibular stenosis,renal cysts,and persistent perilobar nephrogenic rests in a patient with Beckwith-Wiedemann syndrome 27 years after diffuse nephroblastomatosis and Wilms tumor: natural progression or a consequence of treatment?

A27-year-old woman presented with back and abdominal pain. She was diagnosed in infancy with Beckwith-Wiedemann syndrome and bilateral multifocal perilobar nephrogenic rests that progressed to diffuse nephroblastomatosis with neoplastic nephroblastomatous rests at 14 months of age and subsequently to a right Wilms tumor at 5 years of age. Computed tomography of the abdomen during the current admission showed multiple obstructed calices. Ureteroscopic inspection of the left kidney revealed severe intrarenal scarring with multiple infundibular stenosis, hydrocalices, and nephrocalcinosis. Renal biopsy showed sclerotic glomeruli with calcification and scarring and persistent subcapsular nodular renal blastema. Electrocautery incision and balloon dilatation provided temporary pain relief. After discharge, the patient has had two or three episodes of recurrent pain associated with new areas of infundibular stenoses and renal cysts. Bilateral nephrectomy and renal transplantation is being considered for management of progressive disease and relief of intractable pain. The potential causes of progressive and severe intrarenal fibrosis, infundibular stenosis and nephrocalcinosis, and renal cysts in this patient may include abnormal renal development secondary to Beckwith-Wiedemann syndrome itself, radiation or chemotherapy damage, or a combination.     

TP53 codon 72 polymorphisms in favorable histology Wilms tumors

In Wilms tumor (WT), mutations in the gene encoding p53, TP53, are correlated with anaplasia; however TP53 variants have not been studied in favorable histology (FH) WTs. A single nucleotide polymorphism of TP53 encoding either arginine or proline at codon 72 is suggested to alter in vitro p53 behavior. Therefore, we analyzed tissue from 23 consecutive patients with FHWT to determine allelic and genotypic frequencies of Pro72 and Arg72 variants and correlate this with clinical outcomes. Interestingly, our cohort showed a statistically significant over-representation of the Arg allele and Arg/Arg genotype. However, the genotypic and allelic frequencies showed no significant correlation with age, stage, or disease recurrence.     

The pathophysiology of bilateral and multifocal Wilms tumors: What we can learn from the study of predisposition syndromes

Approximately 5% of patients with Wilms tumor present with synchronous bilateral disease. The development of synchronous bilateral Wilms tumor (BWT) is highly suggestive of a genetic or epigenetic predisposition. Patients with known germline predisposition to Wilms tumor (WT1 variants, Beckwith Wiedemann spectrum, TRIM28 variants) have a higher incidence of BWT. This Children's Oncology Group (COG)-International Society for Pediatric Oncology (SIOP-) HARMONICA initiative review for pediatric renal tumors details germline genetic and epigenetic predisposition to BWT development, with an emphasis on alterations in 11p15.5 (ICR1 gain of methylation, paternal uniparental disomy, and postzygotic somatic mosaicism), WT1, TRIM28, and REST. Molecular mechanisms that result in BWT are often also present in multifocal Wilms tumor (multiple separate tumors in one or both kidneys). We identify priority areas for international collaborative research to better understand how predisposing genetic or epigenetic factors associate with response to neoadjuvant chemotherapy, oncologic outcomes, and long-term renal function outcomes.     

The prognosis of prechemotherapy blastemal predominant histology subtype in Wilms tumor: A retrospective study in China

Purpose : This study aimed to retrospectively analyze survival outcomes for Chinese patients with prechemotherapy blastemal predominant histology type Wilms tumors (WTs). Methods : We collected and analyzed clinical data concerning patients aged <15 years with favorable histology (FH) WTs treated at the Sun Yat‐Sen University Cancer Center from December 2005 to May 2016, based on the Children's Oncology Group protocol. Pathological specimens were collected through biopsy or surgical resection before initiation of chemotherapy. We analyzed survival outcomes involving different prechemotherapy histology subtypes. Results : We enrolled 97 patients with FH WTs (median follow‐up, 71.5 months; range, 22.2‐170.7). The total recurrence rate was 17.5%, and the subtype recurrence rates were as follows: blastemal predominant (45.5%), mixed (7.5%), epithelial (14.3%), and mesenchymal (9.5%) (P = .010). Five‐year event‐free survival (EFS) and overall survival (OS) rates were 84.9% and 81.4%, respectively. Respective 5‐year EFS and OS rates for subtypes were as follows: blastemal predominant (54.5% and 68.2%), mixed (90.0% and 88.9%), epithelial (85.7% and 85.1%), and mesenchymal (90.5% and 94.7%). Multivariate survival analyses showed that the blastemal predominant subtype was an independent prognostic factor of EFS (P = .001) and OS (P = .017). Conclusions : Our findings showed that prechemotherapy blastemal predominant WTs had higher recurrence and lower EFS and OS rates. Our findings suggested that, albeit with some deficiencies, blastemal predominant histology WT–diagnosed prechemotherapy may have prognostic relevance. Further research into other potential confounding variables are required to determine whether such patients warrant altered risk‐stratified therapy.     

Natural history and biology of stage A neuroblastoma: a Pediatric Oncology Group Study

PURPOSE: To prospectively analyze the outcome of patients with Stage A neuroblastoma (NB) treated with surgery alone, especially with regard to the prognostic significance of age, tumor site, MYCN copy number, tumor cell ploidy, and histology. PATIENTS AND METHODS: The clinical course of 329 patients with Stage A disease registered on the POG NB Biology Study #9047 between February, 1990 and October, 1997 were evaluated. Age, tumor site, MYCN copy number, tumor cell ploidy, and histology were analyzed for their impact on event-free survival (EFS) and survival (S). RESULTS: The 5-year estimated EFS and S rates for the 329 patients were 91% (+/-3%) and 96% (+/-2%), respectively. The EFS rate was similar for infants younger than 12 months and children age 12 months or older, but age older than 12 months was predictive of lower S rates (P = 0.044). Patients with adrenal, abdominal non-adrenal, thoracic, and cervical tumors had similar S rates. The majority of patients had tumors with favorable biologic features, and only 3% had MYCN amplification. For infants with diploid tumors, the EFS rate was 82% (+/-16%), but effective therapy yielded an S rate of 100%. Rate of S was 80% (+/-26%) and 64% (+/-27%) for patients with unfavorable tumor histology and MYCN-amplified tumors, respectively. CONCLUSION: The outcome for patients with Stage A NB treated with surgery alone is excellent. Although EFS and S rates were significantly worse for patients with MYCN-amplified tumors, a subset achieved long-term remission after surgery alone. For patients with Stage A and MYCN amplification, additional factors are needed to distinguish the patients who will achieve long-term remission with surgery alone from those who will develop recurrent disease.     

Patterns of abdominal relapse and role of sonography in Wilms tumor

This study characterizes the patterns of abdominal recurrence of Wilms tumor and describes the role of sonography in its detection. Twelve patients who had initial tumor recurrence in the abdomen were evaluated. Five patients had recurrence in the kidney; all had nephrogenic rests detected by computed tomography (CT) or magnetic resonance (MR) imaging but not by sonography. The remaining 7 patients had recurrence in the peritoneum (4), the nephrectomy site (2), or the regional lymph nodes (1); tumor spillage had occurred in five of these patients. Four recurrences were detected during therapy, and eight within 3 years after completion of therapy. Seven of the 12 recurrences were first detected by sonography. All 11 sonograms obtained at the time of relapse showed tumor recurrence. Nine patients died a median of 10 months after relapse. The results suggest that regular sonographic surveillance for 3 years after therapy is likely to reveal most abdominal recurrences. Supplementation with CT or MR imaging is indicated for detection of nephrogenic rests.     

Clinical presentation of rhabdoid tumors of the kidney

PURPOSE: We designed this study to differentiate the clinical presentation, particularly the incidence of hematuria, of a rhabdoid tumor of the kidney (RTK), a rare but highly malignant tumor, from a Wilms tumor. PATIENTS AND METHODS: We reviewed patient flow charts from the National Wilms Tumor Study Group and queried participating hospitals to obtain additional information regarding presenting symptoms and laboratory data for fifty patients. Patient ages ranged from 2 days to 3.5 years with a mean of 11 months. We documented the presence of gross and microscopic hematuria, fever, and hypercalcemia. RESULTS: Whereas 75% of children with rhabdoid tumor of the kidney (RTK) had stage III (44%), IV (27%), or V (4%) tumors, 67% of children with Wilms tumors had stage I (41%) or II (26%) tumors. Either gross or microscopic hematuria was present in 84.4% (27/32) of the patients with RTK. Gross hematuria was present in 59% (22/37) of children with RTK compared with 18% previously reported with Wilms tumor. Microscopic hematuria was present in 76% (22/29) of children with RTK compared with 24% previously reported with Wilms tumor. Fever was found in 44% (16/36) of children with RTK, compared with 22% of children previously reported with Wilms tumor. Hypercalcemia was seen 26% (6/23) of children with RTK. CONCLUSION: Although diagnosis of any renal mass still must be confirmed with histopathologic features, a distinct clinical presentation with fever, hematuria, a young age, and high-tumor stage at presentation suggests the diagnosis of RTK.