Rhabdomyosarcoma

Introduction:
Rhabdomyosarcoma also called in short as RMS is a malignancy of mesenchymal origin. It is a tumor of muscle cells called rhabdomyoblasts. It is third most common solid tumor of childhood.

Incidence:
In the United States, about 350 new cases are diagnosed each year in children. Almost two-thirds of RMS cases develop in children under the age of 10. It accounts for more than half of soft tissue sarcomas of childhood.

Associated conditions & predisposing factors:
· Li-Fraumeni syndrome
· Neurofibromatosis type 1
· Beckwith-Wiedemann syndrome
· Cardio-facio-cutaneous syndrome
· Costello syndrome
· Maternal & paternal abuse of cocaine and marijuana

Sites:
Parameningeal- Adjacent to the base of the skull
Orbital - Around the eye
Head and neck
Arms and legs (extremities)
Urinary system and reproductive organs (bladder, vagina, prostate and paratestes sites)

Types of RMS:
Embryonal
Alveolar
Pleomorphic
Undifferentiated

Symptoms:
Rapidly enlarging firm mass
Haematuria,
Dysuria,
Vaginal mass or bleeding
Scrotal mass
Periorbital swelling
Nasal discharge
Lump in abdomen

Investigations:
CT scan or MRI of local site
Bone marrow studies
CT scan chest
Bone scan
Biopsy of the tumor
PET scan

Histopathology: Rhabdomyosarcoma is a small round blue cell tumor

Treatment:
1. Surgery: If the tumor can be completely resectable with achievement of negative margins, then surgery should be done upfront.

2. Chemotherapy: It is used as neo-adjuvant or adjuvant setting. The drugs used are
Vincristine
Ifosphamide
Etoposide
Adriamycin
Cyclophosphamide
Dactinomycin

3. Radiotherapy: It is used to minimize local recurrence in high risk cases.

Prognostic factors:
5-Year survival of RMS is increased over 70%.
Prognostic factors include
Extent of the disease
Primary tumor site: favorable sites are the orbit, head and neck and bladder, all other sites including parameningeal tumors and non-bladder genitourinary sites are classified unfavorable.
Histology subtype: Embryonal & pleomorphic histology tumors have a more favorable outcome while alveolar & undifferentiated has unfavorable outcome.
Age: Patients under one and over 10 years of age have a somewhat less favorable prognosis.
Presence of Distant Metastasis: Metastatic at presentation has a less favorable prognosis.