Unique clinicopathologic and molecular characteristics of urinary bladder tumors in children and young adults

Anaplastic lymphoma kinase1 positive inflammatory myofibroblastic tumor of the urinary bladder: A rare mesenchymal neoplasm with diagnostic and therapeutic implications

Inflammatory myofibroblastic tumors (IMTs) are rare mesenchymal neoplasms characterized by spindle-cell morphology with accompanying inflammatory infiltrates. Originally described in 1939, these tumors can arise in various anatomic locations, with the urinary bladder being a rare site of occurrence but the most common within the genitourinary tract. IMTs typically present as polypoid masses or firm submucosal nodules, often with painless hematuria in bladder cases. Histopathologically, IMTs are composed of myofibroblasts with myxoid stroma and mixed inflammatory cells, predominantly lymphocytes and plasma cells. Immunohistochemically, these tumors commonly express anaplastic lymphoma kinase1 (ALK1), vimentin, smooth muscle actin (SMA), and cytokeratin, with ALK1 serving as a crucial marker for diagnosis. This report details the case of a 31-year-old female presenting with hematuria, found to have a soft tissue mass in the urinary bladder (5.0 × 3.0 cm). Imaging revealed a well-defined lesion with vascularity. Histopathological examination confirmed an IMT, with immunohistochemistry showing diffuse ALK1 positivity, patchy SMA staining, and variable desmin expression, consistent with the diagnosis. IMTs are generally considered neoplasms of intermediate malignant potential. While metastasis is exceedingly rare in bladder IMTs, local recurrence has been reported, particularly in cases of incomplete surgical resection. Recent advances highlight the role of ALK inhibitors in managing unresectable cases, enabling partial cystectomy in select patients. This article underscores the importance of achieving complete surgical excision and highlights the role of ALK expression in diagnosis and differentiation from other spindle-cell neoplasms. Further studies are needed to elucidate the molecular and clinical factors influencing prognosis and to refine treatment strategies for IMTs.

Survival and Analysis of Prognostic Factors for Bladder Malignancies in Children and Adolescents: A Population-based Study

OBJECTIVE

To explore the clinicopathological features and prognosis of pediatric patients with malignant bladder tumors in a population-based cohort.

METHODS

The database Surveillance, Epidemiology, and End Results was used to evaluate all pediatric patients diagnosed with malignant bladder tumors between 1975 and 2018. The log-rank test was used to compare survival curves. Kaplan-Meier estimations were used to create survival curves based on various parameters. The Cox proportional hazards model was utilized to determine the factors that were independently related to mortality.

RESULTS

A total of 263 children and adolescents with bladder malignancies were assessed. Papillary urothelial neoplasms of low malignant potential were the most frequent histologic subtype (35.1%), while embryonal rhabdomyosarcoma was more common during the first decade of life. Survival rates varied significantly by age at diagnosis, with older patients showing better outcomes. When compared to other subtypes, papillary urothelial neoplasms of low malignant potential had the highest overall survival rates (3- and 5-year were 99.2% and 98.3%, respectively). Multivariate analysis of the entire cohort showed that Surveillance, Epidemiology, and End Results stage and surgery were significant independent predictors of progression to disease-specific death in this model.

CONCLUSION

Bladder malignancies are rare in children and adolescents. The prognosis for them varies. The localized stage was independently associated with superior survival and surgery could extend survival time.

Clinical behavior and survival outcome of urothelial bladder cancer in young adults

Background:

Bladder cancer (BC) is rare in young adults and therefore natural history of BC is still debatable. This study aimed to determine clinical behavior and prognosis of BC in patients <40 years.

Materials and Methods:

We reviewed patients (<40 years) managed with urothelial BC from 2003 to 2019. Patients with nonurothelial histology were excluded. Clinical behavior and prognosis such as recurrence, progression, and survival were assessed. The recurrence is defined as a newly diagnosed occurrence of BC at previous or new site(s). Cancer progression is defined as an increase in staging or grade.

Results:

Fifty-five patients inclusive of 45 males and 10 females with a median age of 30.0 (interquartile range [IQR] 25.0–33.0) years were included. The median follow-up was 3.5 (IQR: 1.5–7.0) years. Fifty-one (92.72%) patients were diagnosed with nonmuscle-invasive BC while four (7.27%) patients were diagnosed with muscle-invasive disease. Three out of four patients with muscle-invasive BC died of metastatic disease. According to stage and grade, there were 42 (76.36%) Ta, 9 (16.36%) T1 and 4 (7.27%) having T2 stage while 41 (74.54%) low grade and 14 (25.45%) were having high grade disease. Thirty-six (65.45%) patients remained stable, 13 (26.63%) patients progressed, and 6 (10.90%) patients regressed to lower stage and grade. Higher stage and grade (P = 0.0431) and tumor size >3 cm (P = 0.0454) were significant for recurrence, and higher stage and grade (P = 0.0012) and tumor size >3 cm (P = 0.0055) were associated with tumor progression.

Conclusion:

BC in younger adults is mostly low stage and low grade. We should be vigilant in patients with higher stage and grade as it is related with recurrence, progression, and metastatic disease.

Re-evaluation of histological findings after colocystoplasty and gastrocystoplasty

INTRODUCTION

The potential of malignant transformation and its risk factors after bladder augmentation performed in childhood are still unknown. The necessity of surveillance cystoscopies and biopsies has been questioned in the past decade.

OBJECTIVE

In a previous study, the authors did not detect any malignancy after colocystoplasty (CCP) or gastrocystoplasty (GCP) during the short-term follow-up, however, various alterations of the mucosa were found. A correlation between the nature of histological changes and the frequency of bacterial colonization after CCP were also found. The authors hypothesized that a longer-term follow-up of their patients would reveal an increase in pathological change or show stronger association between the histological alteration, bacterial colonization, and/or stone formation.

PATIENTS AND METHODS

Thirty-five patients (20 cases of colocystoplasties - CCPs; 15 cases of gastrocystoplasties - GCPs) participated in the study published in 2002. All patients were followed biannually with endoscopic assessment and biopsies. Two independent pathologists, evaluated regular biopsies from the native bladder, from the segment used for augmentation and from the anastomosis line. Etiology, frequency of positive urine cultures, and stone events were recorded and compared with histological findings between groups and with the previously published results.

RESULTS

Continuous surveillance allowed the follow-up of 30 patients (CCP 19/20, GCP 11/15) for 20 and 15 years. No malignancies were identified. Results of biopsies showed significant difference between groups (summarized in the tables). Chronic inflammatory changes were found following both types of augmentations, but they were more common in the urothelium following GCP and more common in the colonic mucosa following CCP. The rate of metaplastic lesions was higher after gastrocystoplasty (GCP). Significant association was found between the etiologic factor and the nature of histological change after CCP, as metaplastic lesions occurred only in patients with bladder exstrophy. Stones occurred more frequently in exstrophy patients as well. The nature of the histological changes did not correlate with positive urine cultures in either of the groups. Significantly higher incidence of bacterial colonization and stone occurrence were found after CCP.

CONCLUSIONS

Long-term follow-up of the patients failed to reveal an increase in pathological changes, and no malignancies were observed. According to the results of this study, etiology of bladder dysfunction and the type of augmentation might influence the histological alterations after augmentation cystoplasty. The efficiency of surveillance cystoscopies and biopsies are low. The present data suggest that surveillance cystoscopy and biopsy should not be routinely performed, and should be done only if the symptoms are suspicious for malignancy.

Molecular Pathologic Subtyping of Urothelial Bladder Carcinoma in Young Patients

Urothelial cancer is a heterogeneous disease with different molecular pathways that produce distinct molecular subtypes with specific characteristics and patient survival outcomes that require different therapeutic methods. Urothelial tumors in young patients appear to have distinct genetic features compared with their counterparts in older patients. Using a Lund subtype-specific immunohistochemistry panel, we performed molecular subtype profiling of an urothelial carcinoma case series (n = 49) in patients younger than 45 years of age. We demonstrate that the urothelial carcinoma in young patients tends to be of molecular urothelial-like A subtype (80%) and is associated with favorable, recurrent-free survival (P = .022). In the urothelial-like cluster, we identified a portion of patients (10%) with high-grade non-muscle-invasive cancers (so-called urothelial-like D type) that showed significantly higher levels of squamous differentiation and p16, E2F3, and ki67 expression in addition to aberrant expression of Ck20 and a trend toward lower recurrent-free survival (P = .057). Segregation of the cohort according to the decade of occurrence revealed that all tumors (n = 8) of patients younger than 30 years were clearly classified as urothelial-like A subtype. Statistically more aggressive molecular subtypes, such as urothelial-like D and basal/squamous-like (6%) subtypes, were identified in patients older than 30 years of age. Genomically unstable (2%) and mesenchymal-like (2%) subtypes were classified in the 40- to 44-year age group only. These data suggest that more aggressive molecular subtypes of bladder carcinoma appear and become more frequent with age. Further investigations are needed to validate this hypothesis.

Clinicopathological Characteristics of Urinary Bladder Tumors in Korean Patients 20 Years or Younger

BACKGROUND

To investigate the clinicopathological characteristics of urinary bladder tumors, a rare malignancy, in patients 20 years or younger.

METHODS

Using a retrospective chart review among patients who received bladder surgery at 2 institutions between July 1996 and January 2013, we analyzed the clinicopathological characteristics of urinary bladder tumors in 21 pediatric patients (male:female = 4.25:1.00; mean age, 12.1 years).

RESULTS

Pathology revealed 9 urothelial tumors, 6 rhabdomyosarcomas, 1 low-grade leiomyosarcoma, 1 large cell neuroendocrine carcinoma, 1 inflammatory myofibroblastic tumor, and 3 cases of chronic inflammation without tumors (including 1 xanthogranulomatous inflammation). Urothelial tumors (mean patient age, 16.0 years) were benign or low-grade; and only transurethral resection of the bladder tumor was necessary for treatment. Patients with rhabdomyosarcomas (mean age, 5 years) underwent radiotherapy (if unresectable) or transurethral resection of the bladder tumor (if resectable), after chemotherapy. Of these patients, 2 underwent radical cystectomy, with the remaining patients not receiving a cystectomy. With the exception of one patient, all patients are currently alive and recurrence-free.

CONCLUSION

Urothelial tumors were the most commonly found pediatric bladder tumor, with embryonal rhabdomyosarcoma being the second most common. Urothelial tumors are common in relatively older age. Since urothelial tumors in children typically have a good prognosis and rarely recur, transurethral resection of the bladder tumor is the treatment of choice. Rhabdomyosarcomas are common in younger patients. Since rhabdomyosarcoma is generally chemosensitive, chemotherapy and radiotherapy are the treatment of choice for bladder preservation in these patients.

Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract are genetically different from nodular fasciitis and lack USP6, ROS1 and ETV6 gene rearrangements

AIMS

Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract have a debatable relationship with inflammatory myofibroblastic tumour (generally lacking ALK rearrangement); however, they share several overlapping features with nodular fasciitis of soft tissue. As rearrangement of the USP6 gene has been recently recognised as a recurrent alteration in soft tissue nodular fasciitis, and several other alternative gene fusions have been recently recognised in inflammatory myofibroblastic tumour, the aim of this study was to investigate whether USP6, ROS1 or ETV6 rearrangements were present in these lesions (12 cases).

METHODS AND RESULTS

Fluorescence in-situ hybridisation analysis was performed by the use of bacterial artificial chromosome-derived break-apart probes against USP6, ROS1, and ETV6. Two cases with adequate genetic material from recent paraffin tissue blocks were also tested by use of a solid tumour gene fusion detection assay via next-generation sequencing, targeting >50 known genes involved in recurrent fusions. None of the genitourinary pseudosarcomatous myofibroblastic proliferations was found to harbour USP6 (0/12), ROS1 (0/8) or ETV6 (0/7) rearrangements, and no gene fusions were detected in two cases studied by sequencing.

CONCLUSIONS

Despite overlap in histological and immunohistochemical features between pseudosarcomatous myofibroblastic proliferation and nodular fasciitis, these tumours lack the recently recognised USP6 rearrangements that occur in nodular fasciitis, as well as alternative fusions found in ALK-negative inflammatory myofibroblastic tumours. At present, this diagnosis remains based primarily on clinical, histological and immunohistochemical features.

Immunohistochemical and molecular characterizations in urothelial carcinoma of bladder in patients less than 45 years

Bladder tumours in early-onset patients are rare and seem to exhibit unique clinicopathological features. Only few studies have investigated somatic alterations in this specific age of onset group and evidence is accumulating of a distinct molecular behaviour of early-onset bladder tumours. We collected the largest cohort of early-onset tumours of patients 45 years old or younger and aimed to test genomic alterations typically found in bladder cancer. Tumours of 118 early-onset patients were compared with a consecutive group of 113 cases. Immunohistochemistry of TP53, CK20 and Ki-67 was carried out. Molecular analysis was conducted to test for loss of heterozygosity of chromosome 9 and 17, as well as TP53 and FGFR3 mutations. Fisher´s exact and chi-squared test were appropriately used. No differences in grade/stage characteristics were observed. Overexpressed TP53 was differentially distributed between the two groups. TP53 nuclear accumulation was significantly more frequent in early-onset papillomas, PUNLMPs and pTa low-grade tumours compared to the consecutive cohort (p=0.005). Moreover, chromosome 9 deletions (29.5% vs. 44.6%) and FGFR3 mutations (34.5% vs. 63.7%) were less often detected in early-onset patients (p=0.05 and p<0.0001). By comparing the largest cohort of early-onset bladder cancer patients with an unselected group, we demonstrated that the typical molecular features are not independent of age at diagnosis. Our study supports the hypothesis of a distinct biological behaviour in early-onset tumours.

Aggressive muscle-invasive bladder cancer with sarcomatoid differentiation in a 10-year-old girl: A case report

The present study reports an unusual case of high-grade bladder cancer in a 10-year-old girl who complained of painless hematuria and urinary frequency. The tumor displayed sarcomatoid differentiation and an aggressive behavior, which required the administration of adjuvant chemotherapy. However, the disease progressed and the patient succumbed 6 months after surgery. It is known that the majority of malignant bladder cancers in pediatric patients are low-grade and present at an early stage, whereas sarcomatoid differentiation in the setting of a high-grade urothelial carcinoma is indicative of a poor prognosis. It is important that gross hematuria in pediatric patients is investigated carefully. It is recommended that the management of urothelial neoplasia in young patients should be predominantly decided on the basis of the grade and stage of the tumor rather than the age of the patient.

Genetics of Bladder Malignant Tumors in Childhood

Bladder masses are represented by either benign or malignant entities. Malignant bladder tumors are frequent causes of disease and death in western countries. However, in children they are less common. Additionally, different features are found in childhood, in which non epithelial tumors are more common than epithelial ones. Rhabdomyosarcoma is the most common pediatric bladder tumor, but many other types of lesions may be found, such as malignant rhabdoid tumor (MRT), inflammatory myofibroblastic tumor and neuroblastoma. Other rarer tumors described in literature include urothelial carcinoma and other epithelial neoplasms. Rhabdomyosarcoma is associated to a variety of genetic syndromes and many genes are involved in tumor development. PAX3-FKHR and PAX7-FKHR (P-F) fusion state has important implications in the pathogenesis and biology of RMS, and different genes alterations are involved in the pathogenesis of P-F negative and embryonal RMS, which are the subsets of tumors most frequently affecting the bladder. These genes include p53, MEF2, MYOG, Ptch1, Gli1, Gli3, Myf5, MyoD1, NF1, NRAS, KRAS, HRAS, FGFR4, PIK3CA, CTNNB1, FBXW7, IGF1R, PDGFRA, ERBB2/4, MET, BCOR. Malignant rhabdoid tumor (MRT) usually shows SMARCB1/INI1 alterations. Anaplastic lymphoma kinase (ALK) gene translocations are the most frequently associated alterations in inflammatory myofibroblastic tumor (IMT). Few genes alterations in urothelial neoplasms have been reported in the paediatric population, which are mainly related to deletion of p16/lnk4, overexpression of CK20 and overexpression of p53. Here, we reviewed available literature to identify genes associated to bladder malignancies in children and discussed their possible relationships with these tumors.

Long-term histological and mucin alterations in the neobladder mucosa following urinary bladder augmentation or substitution with gastrointestinal segment

INTRODUCTION

Bladder augmentation is widely used to treat otherwise unmanageable urinary incontinence. However, it is associated with a large number of complications, of which tumor formation is the most severe. Mucin proteins and MUC genes are linked, among others, to malignancies of the urinary bladder and the gastrointestinal system.

OBJECTIVE

To investigate histological alterations as well as changes in expression of MUC1 and MUC2 genes and proteins following different types of urinary bladder augmentation or substitution performed in children and adolescents.

PATIENTS AND METHODS

Between 1988 and 2013, 91 patients underwent urinary bladder augmentation or substitution at the study institute. Patients were included on whom cystoplasty had been performed 4 years previously or earlier, and could have been followed-up prospectively. Thus, 54 patients were involved in the study. In eight patients gastrocystoplasty was performed, in 17 patients ileocystoplasty, and in 22 patients colocystoplasty. Seven patients underwent bladder substitution using a colonic-segment. Biopsies were taken via cystoscopy from the native bladder, from the gastrointestinal segment used for augmentation, and from the anastomotic line between these two. One part of the samples was fixed in formaldehyde for routine histological processing. The other part of the biopsies was embedded into OCT medium, then cryosectioned and fluorescently double-immunostained for MUC1 and MUC2 proteins. Samples from the microscopically dysplastic lesions and from the 15-year-old or older biopsies were processed by laser capture microdissection, and then real-time PCR was done. Data were statistically analyzed by ANOVA and ordinary least squares regression tests.

RESULTS

One adenocarcinoma was found in a female patient, 11 years after colocystoplasty. There were no significant changes in the level of MUC1 and MUC2 proteins and gene expression in the urothelium and in the gastrointestinal segment used for augmentation following ileocystoplasty and gastrocystoplasty. Significant increase in MUC1 and decrease in MUC2 protein levels were detected following colocystoplasty in the large bowel segment used for augmentation, both with qualitative and quantitative methods (p < 0.05) (Figure). The uroepithelium showed no significant change. RT-PCR revealed progressive increase in MUC1 gene expression and decrease in MUC2 gene expression after colocystoplasty in the course of time. It also showed highly increased MUC1 gene expression and decreased MUC2 gene expression in the samples of patients.

CONCLUSIONS

Alterations in gene expression of MUC1 and MUC2 might serve as promising markers for early detection of histological changes after colocystoplasty.

Inflammatory myofibroblastic tumour of the bladder in children: a review

INTRODUCTION

Inflammatory myofibroblastic tumours of the bladder (IMTB) are rare, and feature a benign and reactive proliferation of myofibroblasts. 25% of the reported IMTB cases in the literature occur in children. The present study presents a review of IMTB in children.

DISCUSSION

The data from 42 reported cases of paediatric IMTB in the world literature are summarised, including two recent cases from the present centre. Paediatric IMTB equally affects males and females. It mainly presents with haematuria, dysuria or abdominal pain. Lesions can vary in size, but mean size is 5.5 cm. Mean age is 7.5 years. The aetiology of IMTB is poorly understood, but includes infective or traumatic aetiologies, or a possible clonal lesion. IMTB may specifically show clonal gene rearrangements involving the anaplastic lymphoma kinase (ALK-1) gene. To differentiate IMTB from rhabdomyosarcoma, tissue diagnosis and careful histological analysis are essential. Tumour biopsy can be achieved by a transurethral approach or a transcutaneous approach with ultrasound guidance. Between 35 and 89% of cases of IMTB express ALK-1 by immunohistochemistry. ALK-1 expression is much less common in other bladder soft tissue tumours. ALK-1 is thus useful in the diagnosis of IMTB. The treatment of choice for IMTB is complete surgical resection of the lesion. In children, no proven recurrent or metastatic IMTB episodes are reported after excision. However IMTB recurrences are reported in adults, likely due to incomplete excision. Follow-up after excision is therefore recommended.

CONCLUSIONS

Paediatric IMTB is uncommon. Tissue biopsy is essential for diagnosis. Careful histological assessment is required to differentiate IMTB from malignant paediatric bladder tumours such as rhabdomyosarcoma. ALK-1 expression is useful in confirming the diagnosis of IMTB. Treatment of choice is complete surgical resection of the lesion. Recurrence is reported in adult IMTB. Follow-up is therefore recommended.

Transurethral needle biopsy: a novel technique for pathologic diagnosis of bladder tumors in children

Although rare, both benign and malignant bladder tumors are occasionally encountered in the pediatric population. In the present article, the technique of transurethral needle biopsy, which utilizes an 18-gauge core biopsy instrument inserted through a 9.5 French offset pediatric cystoscope to obtain diagnostic biopsies, is described. This technique has been used successfully in two patients, both of whom had an inflammatory myofibroblastic tumor on biopsy and on final pathology from partial cystectomy. This provides an alternative technique, which may be used when a pediatric resectoscope is not available or in patients with a small caliber urethra.

Urothelial bladder tumour in childhood: A report of two cases and a review

Urothelial bladder tumour in childhood is extremely rare, and almost all the reported cases have been low-grade tumours with a favourable outcome. Here we review 57 reports comprising 127 cases, and we report two new cases.

Molecular characteristics of urothelial neoplasms in children and young adults: a subset of tumors from young patients harbors chromosomal abnormalities but not FGFR3 or TP53 gene mutations

Urothelial neoplasms in children and young adult patients are rare and hypothesized to have a lower rate of recurrence and progression than those of older adults. Because of their rarity, data regarding molecular abnormalities in these tumors are limited. We studied molecular characteristics of urothelial neoplasms from patients under age 30 years using UroVysion fluorescence in situ hybridization (chromosomes 3, 7, 17, and 9p21) and DNA mutational analysis for the FGFR3 and TP53 genes. Seventeen tumors were identified in patients 6-26 years of age, including low-grade papillary urothelial carcinoma (n=10), high-grade papillary urothelial carcinoma (n=5), urothelial papilloma (n=1), and papillary urothelial neoplasm of low malignant potential (n=1). No tumor demonstrated mutation of FGFR3 or TP53. Chromosomal abnormalities were detected only in patients aged ≥19 years: two low-grade urothelial carcinomas had loss of 9p21 as a sole chromosomal abnormality and three high-grade urothelial carcinomas had other or multiple chromosomal abnormalities. Under age 19 years, no tumor showed molecular abnormalities with either method (five low-grade papillary urothelial carcinomas and one each of high-grade papillary urothelial carcinoma, papillary urothelial neoplasm of low malignant potential, and urothelial papilloma). Our results support the idea that mutations of the FGFR3 and TP53 genes are rare or absent in urothelial neoplasms of young patients. In contrast, chromosomal abnormalities detected by UroVysion fluorescence in situ hybridization are sometimes present in patients above 19-20 years of age. This finding supports the recently proposed hypothesis that an age of 19-20 years separates distinct molecular pathways of urothelial carcinogenesis.

Urothelial Tumors of the Urinary Bladder in Two Adolescent Patients: Emphasis on Follow-up Methods

Here we describe two cases of papillary urothelial neoplasm of low malignant potential in adolescent boys. One case was a 16-year-old boy with a polypoid mass beside the right ureteral orifice and the other case was a 13-year-old boy with a papillary mass beside the left ureteral orifice. The initial presentation was hematuria in both cases and the bladder mass was detected by ultrasonography. Complete resection of the bladder tumor was performed by using an 11-Fr pediatric resectoscope. Follow-up has been performed with urine analysis, urine cytology, and bladder ultrasonography or cystoscopy every 3 months with no evidence of recurrence.

Malignant urothelial carcinoma of urinary bladder in a young child: a rare case report

We present a rare case report of a malignant, high-grade, urothelial bladder carcinoma in a 4-year-old boy. The tumor recurred quickly after resection. The recurrence was treated with partial cystectomy plus MVAC (methotrexate, vinblastine, Adriamycin, cisplatin). This is the first reported use of the MVAC regimen for a pediatric bladder tumor.

Update on rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is a malignant childhood tumor of mesenchymal origin that currently has a greater than 70% overall 5-year survival. Multimodality treatment is determined by risk stratification according to pretreatment stage, postoperative group, histology, and site of the primary tumor. Pretreatment staging is dependent on primary tumor site, size, regional lymph node status, and presence of metastases. Unique to RMS is the concept of postoperative clinical grouping that assesses the completeness of disease resection and takes into account lymph node evaluation. At all tumor sites, the clinical grouping, and therefore completeness of resection, is an independent predictor of outcome. Overall, the prognosis for RMS is dependent on primary tumor site, patient age, completeness of resection, extent of disease, including the presence and number of metastatic sites and histology and biology of the tumor cells. Therefore, the surgeon plays a vital role in RMS by contributing to risk stratification for treatment, local control of the primary tumor, and outcome. The current state-of-the-art treatment is determined by treatment protocols developed by the Soft Tissue Sarcoma Committee of the children's Oncology Group.