may be a slightly higher incidence in boys.122 Congenital mesoblastic nephroma has distinctive spindle

cell histopathologic and clinical features that are generally considered benign and rarely metastasizes to

other organs. Congenital mesoblastic nephroma is a mesenchymal tumor with three pathologic variants:

classic congenital mesoblastic nephroma, a cellular subtype, and a mixed variant. Cellular congenital

mesoblastic nephroma subtype is a more aggressive tumor and, though rare, is capable of recurrence

and metastases.123 The cellular subtype is similar in histology to infantile fibrosarcoma and may

represent a visceral form of the disease while classic histology is similar to infantile fibromatosis.124 The

cellular variant of congenital mesoblastic nephroma has been found to have a translocation (t12;15)

(p13;q25) that results in ETV6-NTRK3 fusion protein, a genetic alteration also found in congenital

infantile fibrosarcoma.125 Similar to congenital infantile fibrosarcoma, trisomy 11 is also found in the

cellular subtype of congenital mesoblastic nephroma.126 These chromosomal aberrations distinguish the

cellular variant of congenital mesoblastic nephroma from the classic variant.

Neonates and infants with congenital mesoblastic nephroma present with a palpable abdominal mass

that is indistinguishable from other solid abdominal masses on physical examination. Hematuria is often

present along with vomiting and jaundice in rare cases.127 Hypertension or hypercalcemia is rarely

present. The most common diagnostic imaging studies utilized are ultrasound and CT scan detailing the

presence of a unilateral solid mass with or without cystic components, necrosis, or calcifications. The

mass can be detected on prenatal ultrasound and polyhydraminos may be found in up to 70% of

patients.128 The diagnostic workup precedes in much the same manner as Wilms tumor, and the lesions

are often not discernible on physical examination or preoperative imaging. The standard treatment of

congenital mesonephric nephroma is complete surgical resection with nephrectomy. Wide margins are

recommended because these tumors can infiltrate surrounding renal parenchyma and perinephric

tissues. Local recurrence, though rare, has been reported and is associated with the cellular variant.127

Systemic chemotherapy is reserved for tumors that recur and in rare cases of metastases or unusually

cellular histology.

Clear Cell Sarcoma

Clear cell sarcoma of the kidney is a rare renal neoplasm of childhood, distinct from Wilms tumor.

There are approximately 20 new cases in the United States each year. The median age of diagnosis of

clear cell sarcoma of the kidney is 36 months and the tumor is one of the “unfavorable histology”

tumors studied by the National Wilms Tumor Study Group and the COG. There is a male predominance

with male to female ratio of 2:1.129 Clear cell sarcoma of the kidney has morphologic diversity and is

composed of sarcomatous, nonepithelial cells.130 The classic microscopic pattern of clear cell sarcoma of

the kidney is cords of round or spindle-shaped cells with clear cytoplasm and frequent empty-appearing

“Orphan Annie” nuclei. The cord cells are surrounded by variants of regularly spaced arborizing

fibrovascular septa resulting in cord widths of between four and 10 cells.130 The cellular septa are

characteristic of clear cell sarcoma and aid in diagnosis. The cord cells range from ovoid to spindleshaped and the septa range from thin “chicken-wire” capillaries to sheaths of fibroblast-like cells in a

collagenous matrix.129 Most tumors have the classic histologic pattern though almost all demonstrate a

secondary variant pattern. There are eight variant patterns recognized: myxoid (50%), sclerosing (35%),

cellular (26%), epithelioid (13%), palisading (11%), spindle cell (7%), storiform (4%), and anaplastic

pattern (2.6%).129 Necrosis is associated with poor prognosis and tumors without necrosis are more

often stage 1 tumors with superior outcomes.129

Patients with clear cell sarcoma of the kidney present with a large unilateral abdominal mass that is

best visualized by abdominal ultrasound and CT scan. The tumors are typically well circumscribed and

consist of a solid mass with cystic foci components. Necrosis and hemorrhage are common. There is

gross extension into the renal vein in 5% of cases. The most common site of metastatic disease is

ipsilateral renal hilar lymph nodes (29%), and bone metastases are the most common mode of

relapse.129 Radiographic skeletal survey and radionucleotide bone scan are critical to determine whether

there are bone metastases at diagnosis. Patients may also have lung, brain, or liver metastases and,

therefore, should have chest and central nervous system (CNS) imaging prior to initiation of

chemotherapy for accurate staging. The staging system is similar to Wilms tumor. There is a high rate

of metastases and relapse in early-stage tumors, and intensive chemotherapy is utilized for all cases. The

current COG treatment recommendations for patients with clear cell sarcoma of the kidney include

radical resection of the primary tumor and involved regional lymph nodes, followed by adjuvant

chemotherapy consisting of vincristine, actinomycin-D, doxorubicin, and abdominal radiotherapy (10

Gy) for all stages. Since the addition of doxorubicin to the treatment protocols of clear cell sarcoma of

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the kidney, patients with stage 1 disease have 6-year overall survival of 97%, stage 2 and 3 patients

have 6-year survival of 75% and 77%, respectively (compared to 30% for both stages prior to

doxorubicin), and stage 4 patients have 6-year survival of 50%.129 There is active study within the COG

on the benefit of the addition of cyclophosphamide and etoposide to treatment plans of patients with

clear cell sarcoma of the kidney.131 There is propensity for late relapse and patients are monitored with

abdominal imaging, chest radiography, brain MRI, and bone scanning.

Rhabdoid Tumor of the Kidney

Rhabdoid tumor of the kidney is a rare and aggressive cancer in infancy, constituting 1.8% of renal

neoplasms in children. The cell of origin is unknown and the tumor was originally classified as a

rhabdomyosarcomatoid subtype of Wilms but is now recognized as a distinct histologic tumor type.

Histologically, rhabdoid tumors are well demarcated from the surrounding kidney and composed of

solid and monotonous appearance of sheets of large cells with abundant cytoplasm, cytoplasmic

inclusions, and prominent nucleoli.132 Intense vimentin immunoreactivity is characteristic and these

tumors may also stain for cytokeratin, desmin, and neurofilament. Rhabdoid tumors may have areas of

necrosis and foci of sclerosis.132 Rhabdoid tumors may occur as separate CNS primary tumors and up to

15% of patients with rhabdoid tumor of the kidney develop CNS lesions.133 The overall prognosis of

patients with rhabdoid tumor of the kidney remains poor and age is an important prognostic factor.134

Patients diagnosed with rhabdoid tumors at less than 1 year of age have extremely poor prognoses and

are at high risk for CNS tumors, while patients older than 1 year at diagnosis have better outcomes.

Low stage and female gender have also been reported as features that predict improved survival.133

Because of the small number of patients with this disease and overall poor outcomes, few other

prognostic indicators have been identified. Rhabdoid tumors are characterized by loss-of-function

mutations of the tumor suppressor gene hSNF5/INI1 located at chromosome 22q11, which encodes a

chromatin-remodeling protein complex (SWI/SNF).135 This chromosomal alteration is thought to be a

characteristic genetic defect for rhabdoid tumors of all sites.136 Both acquired and germ-line mutations

have been observed.137 Although the functional consequences are not yet known, mutations in INI1

have been found to result in altered transcription of genes involved in growth and differentiation.

Patients with malignant rhabdoid tumor of the kidney present with a palpable abdominal mass and

often have hematuria. The diagnostic workup proceeds with an abdominal CT scan showing a large

heterogeneous solid mass with areas of necrosis, hemorrhage, or calcifications. The tumor typically

involves the renal hilum. A chest radiograph or chest CT scan should be obtained to evaluate for lung

metastases. Lung metastasis is present in 56% of patients with rhabdoid tumor of the kidney at

diagnosis and is the most common site of metastatic spread.133 Evaluation for CNS disease should also

occur at diagnosis because of the frequency of CNS primaries and metastases in patients with rhabdoid

tumors. Therapy begins with radical nephrectomy and complete surgical resection including involved

regional lymph nodes with paracaval and paraaortic lymph node sampling. Meticulous sampling of any

potentially involved lymph nodes is critical for accurate staging. Patients are staged according to NWTS

staging system, and all patients receive intensified adjuvant chemotherapy and abdominal radiotherapy.

Based on current COG protocols, children with stage 1 to 3 malignant rhabdoid tumor of the kidney are

treated with cyclophosphamide, carboplatin, and etoposide alternating with vincristine, doxorubicin,

and cyclophosphamide for 30 weeks (regimen UH-1). Stage 4 patients receive vincristine, doxorubicin,

cyclophosphamide that is alternated with cyclophosphamide, carboplatin, etoposide, vincristine, and

irinotecan for 30 weeks (regimen UH-2). All patients receive abdominal radiotherapy. The survival rate

for children with rhabdoid tumor of the kidney is dismal, with overall survival rates below 25% and

very few survivors of stage 4 disease. Despite aggressive multimodal therapy, children younger than 1

year with rhabdoid tumor of the kidney have a 4-year survival of 8.8% and children older than 2 years

have 4-year survival of 41.1%. Because previous protocols have had minimal successes with improving

relapse and survival in children with malignant rhabdoid tumors, current COG clinical trials are

examining intensive chemotherapy regimens and experimental agents in this high-risk renal tumor.134

Renal Cell Carcinoma

Renal cell carcinoma is rare in pediatric patients and comprises approximately 5% of all renal tumors in

children and adolescents.4 The tumor is highly aggressive with frequent distant metastases. The median

age of diagnosis of renal cell carcinoma in children is 9 to 10 years, and children who have previously

received cytotoxic chemotherapy may have predisposition to developing this cancer.138 Pediatric renal

cell carcinoma differs from adult renal cell cancer with distinct clinical and biologic differences. The

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microscopic pattern does not typically fit well within the standard adult subtypes. In general, histology

is consistent with papillary adenocarcinoma, renal cell carcinoma not otherwise specified, and clear cell

adenocarcinoma subtypes.139 High nuclear grade and increased vimentin expression is found in higherstage cases.140 Patients with von Hippel–Lindau syndrome may present with bilateral renal cell

carcinoma. Tuberous sclerosis, Birt–Hogg–Dube syndrome, and hereditary leiomyomatosis are other

hereditary syndromes associated with renal cell carcinoma.5 It is routine to test for translocations of the

Xp11.2 and 6p21 loci, nonrandom genetic alterations that are characteristic of renal cell carcinoma.141

Tumors with Xp11.2 translocations have papillary and clear cell features and are a separate entity in the

World Health Organization classification of renal tumors.142 This translocation may be present in up to

70% of pediatric renal cell carcinoma and involves the fusion of the TFE3 gene, a transcription factor

belonging to the microphtalmia (MiTF) family.143 The translocation involving 6p21 is the second most

common translocation in pediatric renal cell carcinoma and results in the fusion of TFEB, also a member

of the MiTF transcription factor family.143

Patients may present with a large palpable abdominal mass. Abdominal pain, hematuria, weight loss,

joint pain, and anorexia may also be present. Cross-sectional abdominal and pelvic imaging (CT scan or

MRI) along with chest radiography and/or chest CT scan is critical to define the locoregional extent of

the mass and to determine metastatic spread. Distant metastatic disease is present in up to 30% of

pediatric patients at diagnosis, most commonly to lung (64%), liver (57%), and bone (42%).143 Local

lymph node involvement does not necessarily predict poor outcome in renal cell carcinoma in

children.144 Imaging may show a large nonenhancing renal mass with necrosis or hemorrhage.

Calcifications are more common in children with renal cell carcinoma than Wilms tumor.145 Compared

to adults, children with renal cell carcinoma present with higher-stage and higher-grade disease.143

Children with renal cell carcinoma are staged on the basis of the International Union Against Cancer

(UICC)/American Joint Committee on Cancer (AJCC; TNM) system although some studies utilize the

modified Robson staging classification system.141,146 The overall survival at 20 years for pediatric renal

cell carcinoma is 54.9%.147

If the mass is resectable at diagnosis, standard treatment is radical nephrectomy with lymph node

sampling, followed by combination adjuvant chemotherapy, immunotherapy, and radiotherapy based on

surgical pathology. The role of lymph node dissection for renal cell carcinoma has not been determined.

Partial nephrectomy is reserved for patients at high risk of postoperative renal failure and multiple

renal tumors, particularly patients with genetic syndrome-related disease. There are reports of

successful partial nephrectomy for small, unilateral, low-stage tumors. The role of chemotherapy is

unproven, as the administration of chemotherapy has not significantly improved survival outcomes.

There is some evidence that immunotherapy (IL-2) may be beneficial in select cases of renal cell

carcinoma.148 The COG recently completed a clinical trial (2006 to 2014) examining outcomes of highrisk renal tumors with complete surgical resection, intensive chemotherapy regimens, and radiotherapy.

The most common agents utilized are combinations of vincristine, actinomycin-D, doxorubicin,

cyclophosphamide, irinotecan, etoposide, and carboplatin

(https://clinicaltrials.gov/show/NCT00335556). This prospective study should yield critical results on

the optimal management of adjuvant therapy for this tumor.

RHABDOMYOSARCOMA

Epidemiology and Genetic Risk

Rhabdomyosarcoma is the most common soft tissue sarcoma in children with an overall incidence of

approximately 350 cases per year in the United States.149 The median age of presentation is 7 years of

age and the majority of patients are diagnosed prior to 10 years of age. There is a slight male

predominance and a slightly higher incidence in African-American children.4 Rhabdomyosarcoma tumors

are classified as embryonal, alveolar, or pleomorphic histologic subtypes. Embryonal

rhabdomyosarcoma (68%) is the most frequent histologic type and occurs in children younger than 4

years.149 Alveolar rhabdomyosarcoma (31%) and pleomorphic subtypes (1%) occur more commonly in

older children. The overall incidence of rhabdomyosarcoma has not changed much in the last 30 years

although there has been an increase in incidence of the alveolar subtype and in cases presenting with

distant metastases.149 The overall survival for rhabdomyosarcoma has increased from 25% to more than

80% in the last four decades. This is largely due to improvements in multimodal therapies including

radical surgery, intensive combination chemotherapy, and radiotherapy. Patients with embryonal

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subtype have the best overall survival. Patients with smaller size tumors and favorable anatomic sites

also have significant survival advantage. Age relates independently to survival outcomes with infants

(<1 year of age) and adolescents (>10 years of age) more likely to have poor outcome and

unfavorable histologic features.150

Rhabdomyosarcoma is often associated with congenital malformations, most commonly the CNS and

genitourinary systems, with nearly an eightfold increase in CNS anomalies in children with

rhabdomyosarcoma.151 At least 32% of children with rhabdomyosarcoma have at least one congenital

anomaly and nearly half are considered major defects. The rate of genitourinary defects in

rhabdomyosarcoma is similar to that seen in children with Wilms tumors. There are also several familial

syndromes associated with rhabdomyosarcoma. Children in families with Li–Fraumeni syndrome are at

risk of developing rhabdomyosarcoma along with cancers of the breast, bone, brain, lung, and adrenal

gland.152 Rhabdomyosarcoma has been reported at an increased incidence in patients with

neurofibromatosis type 1 and in patients with Beckwith–Wiedemann syndrome.153–155 Environmental

factors have also been found to have a role in the development of rhabdomyosarcoma. Parental use of

recreational drugs has been associated with an increased risk. Several studies have suggested that

cocaine and marijuana use in parents may increase the risk of rhabdomyosarcoma in offspring.156

Pathology and Biologic Features

Rhabdomyosarcoma is a heterogeneous group of tumors. The origin is thought to be embryonal

mesenchyme that gives rise to striated skeletal muscle. Rhabdomyosarcoma can occur in any skeletal

muscle group but most commonly affected sites are head and neck, trunk, and genitourinary track. The

Intergroup Rhabdomyosarcoma Study Group (IRSG), now the Soft Tissue Sarcoma Committee of the

COG, classifies patients with rhabdomyosarcoma into the International Classification of

Rhabdomyosarcoma (ICR) that is predictive of outcome among patients with different histologic

subtypes.157 Embryonal rhabdomyosarcoma is a heterogeneous subtype with histologic features that

range from primitive mesenchymal cells to highly differentiated muscle cells. The small round blue cells

consist of nuclei that are generally small with a light chromatin pattern. The microscopic pattern is

moderately cellular with loose myxoid stroma.157 Embryonal rhabdomyosarcoma comprises up to 75%

of rhabdomyosarcoma tumors and is considered an intermediate prognosis tumor in terms of outcomes.

Alveolar rhabdomyosarcoma is associated with poor prognosis. The tumors consist of small round cells

with coarse chromatin and anastomosing fibrovascular connective tissue septa forming an alveolar

pattern that is similar to lung in appearance (Fig. 105-10).157 Botryoid tumors have excellent prognosis

and have similar histologic characteristics of embryonal tumors but grow into hollow spaces such as

bladder or vagina, assuming a characteristic grapelike appearance. Spindle cell rhabdomyosarcoma is

another subtype of embryonal rhabdomyosarcoma that occurs most commonly at paratesticular sites

and generally has excellent prognosis. Pleomorphic rhabdomyosarcomas are extremely rare in children

and more common in adults. Rhabdomyosarcoma is detected on immunohistochemistry by desmin,

myoglobin/Myo-D, or muscle-specific actin staining.158 Myogenic phenotype may also be determined by

electron microscopy.159

Figure 105-10. Microscopic image of typical lung-like appearance of an alveolar rhabdomyosarcoma. (From Rubin E, Farber JL.

Pathology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 1997, with permission.)

Recurrent chromosomal alterations have been identified in rhabdomyosarcoma, particularly in

alveolar subtypes.160 Consistent translocations between chromosome 2 and 13, t(2:13)(q35;q14), have

been identified and occur in up to 55% of alveolar rhabdomyosarcoma tumors. The translocation results

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in fusion of the PAX3 and FKHR genes, both transcription factors that function in muscular

development. The resulting gain of function fusion gene is thought to alter cellular apoptosis, growth,

and oncogenesis.161 Another PAX gene translocation, t(1;13) (p36;q14), results in fusion gene PAX7-

FKHR and also occurs in alveolar tumors.162 These recurrent chromosomal alterations rarely occur in

embryonal rhabdomyosarcoma. Nearly 80% of alveolar tumors have PAX3-FKHR or PAX7-FKHR fusions

detectable by polymerase chain reaction (PCR) and may aid in diagnosis.

Embryonic rhabdomyosarcoma is associated with allelic loss at chromosome 11p15.5, a possible

tumor suppression region.163 The mechanism of loss appears to preferentially maintain the paternal

allele and lose the maternal allele, suggesting genomic imprinting.164 Other genetic abnormalities have

been identified through comparative genomic hybridization with whole chromosome gains and losses in

embryonal rhabdomyosarcoma.165 Genomic amplifications have been detected in alveolar subtypes and

in embryonal rhabdomyosarcoma with anaplasia.165

Presentation and Diagnosis

Rhabdomyosarcoma can arise at any mesenchyme-containing site in the body. The presenting signs and

symptoms depend on the site affected. Approximately 35% of all rhabdomyosarcoma tumors arise in the

head and neck region and include parameningeal and nonparameningeal sites. Tumors in these areas

may cause headache, facial and cervical swelling, nasal obstruction or discharge, recurrent otitis media,

and cranial nerve palsies.166 Tumors of the genitourinary track account for 25% of rhabdomyosarcoma

and are most commonly located in the bladder and the prostate gland. Perineal and perianal lesions may

also occur. Patients may present with a palpable abdominal or pelvis mass, hematuria, dysuria, or

urinary retention. Botryoid tumors are common in the vagina and the cervix and may present with

vaginal bleeding and inflammation. The friable grapelike mass may protrude from the vaginal orifice.

Paratesticular rhabdomyosarcoma presents with a painless mass in the scrotum that is typically

distinguishable from the testicle. Extremity rhabdomyosarcoma tumors may present as swelling and

pain after a traumatic injury to the extremity involved. Chest wall, paraspinal, and abdominal wall

rhabdomyosarcoma are considered trunk sites and often present with palpable masses or chest wall

pain. Additional primary sites include retroperitoneum, abdomen, and pelvis. These lesions may present

as a palpable abdominal mass or with abdominal pain. There is seldom mass effect such as rectal or

bladder obstruction. Biliary rhabdomyosarcoma may cause jaundice, fever, and right upper quadrant

abdominal pain.

The diagnostic workup for rhabdomyosarcoma includes a thorough history and physical examination,

followed by cross-sectional imaging of the involved site by CT scan or MRI. Local, regional, and distal

metastatic extent of disease should be determined with assessment for abnormal appearing lymph

nodes. PET scan may aid in detection of disease for adequate staging.167 Complete blood count, serum

chemistries, and liver function tests are routinely evaluated. Patients with suspected rhabdomyosarcoma

should have bone marrow biopsies and aspirates performed to determine metastatic spread to bone

marrow. Chest CT scan or chest radiograph is required to identify lung metastases. Bone scintigraphy

should be obtained to search for cortical bone metastases. For most cases, brain CT scan and cerebral

spinal fluid testing are reserved for patients with known CNS lesions or symptoms. An adequate biopsy

is required to histologically confirm diagnosis. If the lesion is small or judged resectable on

presentation, excisional biopsy with clear microscopic margins should be performed. If the tumor

involves contiguous organs, major blood vessels, or nerves then incisional biopsy is performed. It is

critical that the specimen is sent fresh to the pathologist without formalin and that enough tissue is

obtained for microscopic evaluation and cytogenetic analysis.

Table 105-6 TNM Pretreatment Staging System

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Staging

The most widely utilized staging system for rhabdomyosarcoma is based on the tumor, node, and

metastases (TNM) staging system. TNM staging system is applied prior to treatment and assesses

disease site of origin, tumor size, nodal status, and metastases as factors in prognosis (Table 105-6). This

system was prospectively tested in IRSG clinical trials IRS-III and IV and reflects the biology of the

tumor.168 Most tumors are larger than 5 cm in size and 20% present with distant metastases at diagnosis

(stage 4). Stage 1 tumors involve the head and neck, genitourinary (nonbladder/prostate), and biliary

tract sites. Regional nodes may or may not be involved with stage 1 tumors. Stage 2 tumors involve the

bladder/prostate gland, extremity, and cranial, parameningeal, retroperitoneal, and trunk sites and are

smaller than 5 cm without lymph node involvement. Stage 3 tumors are the same anatomic sites as

stage 2 and are larger than 5 cm with or without lymph node involvement. Any rhabdomyosarcoma

tumor with distant metastases is considered stage 4 disease.

Clinical Group Assessment and Risk Status

Both stage and group assessment is used to assign risk categories and to determine treatment plan. The

IRSG developed a surgical–pathologic clinical grouping system to standardize risk assessment in the IRS

I and II therapeutic clinical trials. Patients are grouped into four risk groups on the basis of

postoperative assessment of disease before initiating chemotherapy or radiation (Table 105-7).169

Clinical group accurately predicts outcomes in patients with rhabdomyosarcoma.169 Group I patients

have excellent prognosis with localized tumors that are completely excised while group II patients have

tumors that have microscopic residual disease or regionally invasive disease involving lymph nodes.

Group III patients have gross residual disease or incisional biopsy, and group IV patients have distant

metastases at presentation. Stage, clinical group, histology, age, and anatomic site are utilized to

identify low, intermediate, and high-risk categories, and therapy is allocated on the basis of patient risk

status. Favorable sites are orbit, head and neck (except parameningeal), genitourinary (except bladder

and prostate), and biliary tract sites. Unfavorable sites are bladder/prostate, extremity, parameningeal,

trunk, retroperitoneal, pelvis, and all other sites. Combinations of chemotherapy and radiotherapy are

administered on the basis of risk group assignment. Alveolar and embryonal histology subgroups

contrast in prognostic factors and in survival outcomes.

In patients with nonmetastatic rhabdomyosarcoma, tumors considered low-risk are embryonic

rhabdomyosarcoma tumors (stage 1 or 2) located at favorable histology sites.170 Embryonal tumors at

unfavorable sites may also be assigned as low-risk group if the tumor is grossly completely resected

(group 1 or II). There are two subsets of low-risk patient groups. Subset A (stage 1, group 1 or IIa; stage

2, group 1, group III orbit) is associated with worse failure-free survival (82%) in patients older than 10

years, though overall survival is the same as in younger patients (92%). This suggests excellent salvage

therapy in this subgroup of patients. Low-risk subset B patients (stage 1, group IIb or IIc, stage 1, group

III nonorbit; stage 2, group II, stage I, group 1 or II) with tumors larger than 5 cm also have worse

failure-free survival (77%) but similar overall survival as patients with smaller tumors (93%).170 The

intermediate-risk embryonal rhabdomyosarcoma group comprises patients with unfavorable anatomic

sites with tumor remaining after surgical excision. This risk group has worse survival outcomes than

patients with low-risk tumors. In this group, patients with unresectable extremity rhabdomyosarcoma

have extremely poor failure-free (43%) and overall (46%) survival.

Table 105-7 Surgical–Histopathologic Clinical Grouping System for the

Intergroup Rhabdomyosarcoma Studies I and II

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