What are the other Names for this Condition? (Also known as/Synonyms)

• Genitourinary Rhabdomyosarcoma
• Rhabdomyosarcoma of the Urogenital System
• RMS of the Genitourinary System

What is Rhabdomyosarcoma of the Genitourinary System? (Definition/Background Information)

• A rhabdomyosarcoma (RMS) is a very uncommon high-grade malignant ‘skeletal muscle’ tumor of the soft tissues. RMS tumors are poorly-defined, fleshy, expanding masses that form deep within the body tissues or below the skin surface
• Rhabdomyosarcoma of the Genitourinary System is a rare tumor seen in the genitourinary tract; the genitourinary or urogenital system includes the urinary and genital organs
• All four major subtypes have been observed in the urogenital system, including
  • Embryonal rhabdomyosarcoma (ERMS)
  • Alveolar rhabdomyosarcoma (ARMS)
  • Pleomorphic rhabdomyosarcoma (PRMS) - very rarely noted
  • Spindle cell/sclerosing rhabdomyosarcoma (SCSRMS)
• In the urogenital system, the urinary bladder, urethra, prostate gland, paratestis, and kidney have been observed with this tumor type
  • ERMS is the most common pediatric sarcoma of urinary tract. It generally affects the bladder, urethra, and prostate gland
  • Also, ERMS is the most common paratesticular mesenchymal tumor, mostly seen in young children and adolescents
  • Kidney ERMS is rare

Incidence:

• The tumors are observed in both children and adults
• Both males and females are affected 
• All races and ethnic groups are at risk

Risk factors:

• Individuals with Li–Fraumeni syndrome showing changes in TP53 gene are at an elevated risk for rhabdomyosarcoma
• Neurofibromatosis type 1, Noonan syndrome, and Costello syndrome places one at an elevated risk for urinary bladder and urachus ERMS
• Another risk factor for bladder RMS is Beckwith-Wiedemann syndrome (around 5% of RMS cases are associated with BWS)
• Mosaic variegated aneuploidy syndrome type 1 is another risk factor for urinary bladder ERMS

Cause: Several genetic defects are noted.

• Sporadic ERMS shows chromosomal abnormalities involving chromosome 8 (most frequently); monosomy 10 and 15 and extra genetic material on chromosomes 2, 11, 12, 13, and 20, are noted to a lesser extent
• SCSRMS encompasses a group with distinct molecular subtypes, including VGLL2::NCOA2, VGLL2::CITED2, and TFCP2::NCOA2 rearrangements, or MYOD1 mutation (not seen in paratesticular rhabdomyosarcoma)
• PAX3::FOXO1 fusion or PAX7::FOXO1 fusion gene is detected in most ARMSs (85% of the cases)

Signs and symptoms:

• The tumors can arise in a variety of anatomical locations in the urogenital system
• Depending on the location of the tumor the signs and symptoms vary
• Scrotal mass, blood in urine, and an inability to empty the bladder (urinary retention) are the most common presentations

Diagnosis:

• Blood and urine tests
• Radiological studies
  • Ultrasound of abdomen
  • CT and MRI scan of abdomen
• Tissue biopsy of the tumor mass can help achieve a definitive diagnosis
• Molecular testing is important

Complications:

• Emotional stress
• Tumor metastasis to different organs and regions
• Incomplete removal results in tumor recurrence

Treatment:

• American Joint Committee on Cancer (AJCC) staging system or Union for International Cancer Control (UICC) system for soft tissue sarcoma is used
• Staging for rhabdomyosarcoma in children is based on the Intergroup Rhabdomyosarcoma Study Group (IRSG) system that mainly focuses on site of origin of the tumor
• Treatment depends on the location and the size of the tumor
• Surgery remains the primary treatment modality
• Other options include chemotherapy and radiation therapy

Prevention: Presently, it is not possible to prevent the formation of Rhabdomyosarcoma of the Genitourinary System.

Prognosis:

• Fusion status can affect prognostic outcomes along-with cancer stage
• In ERMS, age of the patient and tumor stage are key indicators
• Fusion positive ARMS tumors have worse outcomes than fusion negative ERMS
• In individuals with ARMS tumors, having PAX3::FOXO1 fusion gene is worse than PAX7::FOXO1 fusion gene
• For SCSRMS, MYOD1 mutation is associated with aggressive tumor behavior and poorer outcomes
• VGLL2::NCOA2 and VGLL2::CITED2 fusion gene rearrangements predict slightly better outcomes