Rhabdomyosarcoma (RMS), is a type of cancer, specifically a sarcoma (cancer of connective tissues), in which the cancer cells are thought to arise from skeletal muscle progenitors. It can also be found attached to muscle tissue, wrapped around intestines, or in any anatomic location. It mostly occurs in areas naturally lacking in skeletal muscle, such as the head, neck, and genitourinary tract.
- Head lump
- Neck lump
- Tongue lump
- Genitourinary symptoms
- Prostate lump
Genetic syndromes include the following:
- Neurofibromatosis (4-5% risk of any one of numerous malignancies)
- Li-Fraumeni syndrome (germline mutation of the tumor suppressor gene TP53)
- Rubinstein-Taybi syndrome
- Gorlin basal cell nevus syndrome
- Beckwith-Wiedemann syndrome
- Costello syndrome 9
A higher prevalence of congenital anomalies are observed in patients who later develop rhabdomyosarcoma with locations as follows:
- Genitourinary (GU) tract
- CNS (ie, Arnold-Chiari malformation)
- GI tract
- Cardiovascular system
Environmental factors appear to influence the development of rhabdomyosarcoma, as follows:
- Parental use of marijuana and cocaine
- Intrauterine exposure to X-rays
- Previous exposure to alkylating agents
The diagnosis of rhabdomyosarcoma is made by a pathologist; he or she will examine a biopsy of the tumor under the microscope and arrive at the diagnosis of rhabdomyosarcoma based on the morphology (appearance) of the tumor cells and the results of immunohistochemical stains.
Diagnosis of rhabdomyosarcoma depends on recognition of differentiation toward skeletal muscle cells. The proteins myoD1 and myogenin are transcription factor proteins normally found in developing skeletal muscle cells which disappears after the muscle matures and becomes innervated by a nerve. Thus, myoD1 and myogenin are not usually found in normal skeletal muscle and serve as a useful immunohistochemical marker of rhabdomyosarcoma.
Early manifestation can be misdiagnosed as a pseudotumor that is non responsive to steroid treatment.
MRI is the imaging modality of choice for the assessment of the primary adult rhabdomyosarcoma involving most body regions with additional value of diffusion weighted imaging and whole body MRI for staging.
Treatment for rhabdomyosarcoma consists of chemotherapy, radiation therapy and sometimes surgery. Surgery to remove the tumor may be difficult or impossible depending on the location of the tumor.
If there is no evidence of metastasis, surgery combined with chemotherapy and radiation offers the best prognosis. Patients whose tumors have not metastasized usually have a good chance for long-term survival, depending on the subtype of the tumor.
St Jude's Children's Research Hospital reports that more than 70% of children diagnosed with localized rhabdomyosarcoma have long-term survival.