Rhabdomyosarcoma in children (also called “rhabdo” or RMS) is a tumor in which malignant (cancer) cells look like young, immature muscle cells. It is the most common soft tissue sarcoma (cancer of soft and connective tissue) found in children. In the United States, about 350 new cases are diagnosed each year in children under 20 years of age. Almost two-thirds of pediatric rhabdomyosarcoma cases are diagnosed in children under 6.
RMS can arise in any muscle of the body, but the most common sites are:
- Adjacent to the base of the skull (parameningeal)
- Around the eye (orbital)
- Other sites in the head and neck, such as the cheek or lip
- Arms and legs (extremities)
- Urinary and reproductive organs (genitourinary system) including bladder, vagina, prostate and soft tissue around the testicles
In children, there are two major subtypes of RMS, based on the tumor cell appearance under the microscope:
- Embryonal rhabdomyosarcoma (ERMS): It is the most common type (60-70% of cases) and tends to occur in younger children.
- Alveolar rhabdomyosarcoma (ARMS): More commonly found in adolescents.
Signs and Symptoms of Rhabdomyosarcoma
The most common presenting symptom of RMS is a growing mass or swelling wherever the tumor forms. Other signs and symptoms depend on the location of the primary tumor, which are described below.
For tumors presenting in the urinary and reproductive organs, children may experience blood in the urine, difficulty urinating, or bleeding from the vagina.
For tumors presenting adjacent to the base of skull (includes the nasal cavity, middle ear, and sinuses), the cancer can cause facial asymmetry, blurred vision, difficulty breathing, ear bleeding or discharge, headaches and facial pain. Swelling or bulging around the eye is a common sign of a tumor arising around the orbit.
Extremity tumors (those in the arms or legs) often present as a rapidly enlarging, firm mass.