Rhabdomyosarcoma

Overview
A rhabdomyosarcoma 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 anywhere, to include the neck area. It is most common in children ages one to five, and teens aged 15 to 19, although quite rare in the latter. It can be a cardiac manifestation of tuberous sclerosis.

Rhabdomyosarcoma is a relatively rare form of cancer. Its two most common forms are embryonal rhabdomyosarcoma and alveolar rhabdomyosarcoma. In the former, which is more common in younger children, the cancer cells resemble those of a typical 6-to-8-week embryo. In the latter, which is more common in older children and teenagers, they resemble those of a typical 10-to-12-week embryo.

Diagnosis
When rhabdomyosarcoma is suspected, tests will be run for blood, muscle, and marrow.

Diagnosis of rhabdomyosarcoma depends on recognition of differentiation toward skeletal muscle cells. The protein myo D1 is a protein normally found in developing skeletal muscle cells which disappears after the muscle matures and becomes innervated by a nerve. Thus, myo D1 is not found in normal skeletal muscle and serves as a useful immunohistochemical marker of rhabdomyosarcoma.

Treatment
Treatment for rhabdomyosarcoma consists of chemotherapy, radiation therapy and sometimes surgery. Surgery to remove the tumor is often difficult or impossible because the tumor is usually embedded deep within the tissue, leaving it difficult to reach. If a tumor presents itself in the extremities, amputation is often necessary to improve survival.

If there is no evidence of metastasis, surgery combined with chemotherapy and radiation offer the best prognosis. Patients whose tumors have metastasized usually have a poor chance for long-term survival. In patients who began treatment before metastasis, the prognosis is better, although the disease is generally incurable because the tumors that cannot be surgically removed tend to spread.