Rhabdomyosarcoma
Encyclopedia
A rhabdomyosarcoma is a type of cancer
, specifically a sarcoma
(cancer of connective tissue
s), 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. Most occur in areas naturally lacking in skeletal muscle, such as the head, neck, and genitourinary tract.
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.
It is most common in children ages one to five, and is also found in teens aged 15 to 19, although this is more rare. This cancer is also an adult cancer but it is rare.
St. Jude Children's Research Hospital
reports that rhabdomyosarcoma is the most common soft tissue sarcoma in children. Soft tissue sarcomas make up about 3% of childhood cancers.
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.
International Classification of Rhabdomyosarcoma
Several additional subtypes of rhabdomyosarcoma exist that do not fit into the International Classification scheme. Pleomorphic rhabdomyosarcoma usually occurs in adults rather than children, and, thus, is not included in this system. Sclerosing rhabdomyosarcoma
is a rare rhabdomyosarcoma subtype recently characterized by Folpe, et al; it is not included in this system.
Although botryoid and spindle cell rhabdomyosarcoma are classically considered as subtypes of embryonal rhabdomyosarcoma
, they have more favorable clinical behavior and prognosis than classic embryonal rhabdomyosarcoma.
, 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.
alloy embedded in muscle (e.g. shrapnel).
However, the tungsten alloy contained 6% Nickel
and 3% Cobalt
, which are known carcinogens. A synergistic effect of alloying tungsten with Ni and Co is suggested (i.e. increasing the toxicity relative to either of the pure metals).
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, specifically a sarcoma
Sarcoma
A sarcoma is a cancer that arises from transformed cells in one of a number of tissues that develop from embryonic mesoderm. Thus, sarcomas include tumors of bone, cartilage, fat, muscle, vascular, and hematopoietic tissues...
(cancer of connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
s), in which the cancer cells are thought to arise from skeletal muscle
Skeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
progenitors. It can also be found attached to muscle tissue, wrapped around intestines, or in any anatomic location. Most occur in areas naturally lacking in skeletal muscle, such as the head, neck, and genitourinary tract.
Presentation
Its two most common forms are embryonal rhabdomyosarcomaEmbryonal rhabdomyosarcoma
Embryonal rhabdomyosarcoma is a rare histological form of cancer of connective tissue wherein the mesenchymally-derived malignant cells resemble the primitive developing skeletal muscle of the embryo...
and alveolar rhabdomyosarcoma
Alveolar rhabdomyosarcoma
Alveolar rhabdomyosarcoma is a type of rhabdomyosarcoma characterized by its appearance, which is similar to the alveoli of the lungs.It can be associated with a fusion protein between PAX3 and FKHR ....
. 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.
Epidemiology
Rhabdomyosarcoma is a relatively rare form of cancer.It is most common in children ages one to five, and is also found in teens aged 15 to 19, although this is more rare. This cancer is also an adult cancer but it is rare.
St. Jude Children's Research Hospital
St. Jude Children's Research Hospital
St. Jude Children's Research Hospital, founded in 1962, is a leading pediatric treatment and research facility focused on children's catastrophic diseases. It is located in Memphis, Tennessee. It is a nonprofit medical corporation chartered as a 501 tax-exempt organization under IRS regulations.In...
reports that rhabdomyosarcoma is the most common soft tissue sarcoma in children. Soft tissue sarcomas make up about 3% of childhood cancers.
Diagnosis
The diagnosis of rhabdomyosarcoma is made by a pathologist, a physician who specializes in the diagnosis of disease. The pathologist will examine a biopsyBiopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
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
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
. 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.
Classification
Several different histological subtypes of rhabdomyosarcoma exist, each of which has different clinical and pathological characteristics. Prognosis and clinical behavior of the tumor is also partially dependent on histologic subtype. Multiple classification systems have been proposed for subclassifying these tumors. The most recent classification system, the "International Classification of Rhabdomyosarcoma", was created by the Intergroup Rhabdomyosarcoma Study. This system attempts to combined elements of the previous systems and correlate these with prognosis based on tumor type.International Classification of Rhabdomyosarcoma
| Histologic Subtype | Prognosis |
|---|---|
| Botryoid Rhabdomyosarcoma Sarcoma botryoides Sarcoma botryoides or botryoid sarcoma or botryoid rhabdomyosarcoma is a subtype of embryonal rhabdomyosarcoma, that can be observed in the walls of hollow, mucosa lined structures such as the nasopharynx, common bile duct, urinary bladder of infants and young children or the vagina in females,... |
Superior Prognosis |
| Spindle cell rhabdomyosarcoma Spindle cell rhabdomyosarcoma Spindle cell rhabdomyosarcoma is a subtype of embryonal rhabdomyosarcoma first described by Cavazzana, Schmidt and Ninfo in 1992. This subtype has a more favorable clinical course and prognosis than usual embryonal rhabdomyosarcoma. Spindle cell rhabdomyosarcoma typically occurs in young males... |
Superior Prognosis |
| Embryonal rhabdomyosarcoma Embryonal rhabdomyosarcoma Embryonal rhabdomyosarcoma is a rare histological form of cancer of connective tissue wherein the mesenchymally-derived malignant cells resemble the primitive developing skeletal muscle of the embryo... |
Intermediate Prognosis |
| Alveolar rhabdomyosarcoma Alveolar rhabdomyosarcoma Alveolar rhabdomyosarcoma is a type of rhabdomyosarcoma characterized by its appearance, which is similar to the alveoli of the lungs.It can be associated with a fusion protein between PAX3 and FKHR .... |
Poor Prognosis |
| Undifferentiated Sarcoma | Poor Prognosis |
Several additional subtypes of rhabdomyosarcoma exist that do not fit into the International Classification scheme. Pleomorphic rhabdomyosarcoma usually occurs in adults rather than children, and, thus, is not included in this system. Sclerosing rhabdomyosarcoma
Sclerosing rhabdomyosarcoma
Sclerosing rhabdomyosarcoma is a rare subtype of rhabdomyosarcoma that was characterized by Folpe et al. in 2002. It is microscopically characterized by primitive round cells forming microalveoli, nests, and cords in a sclerotic background....
is a rare rhabdomyosarcoma subtype recently characterized by Folpe, et al; it is not included in this system.
Although botryoid and spindle cell rhabdomyosarcoma are classically considered as subtypes of embryonal rhabdomyosarcoma
Embryonal rhabdomyosarcoma
Embryonal rhabdomyosarcoma is a rare histological form of cancer of connective tissue wherein the mesenchymally-derived malignant cells resemble the primitive developing skeletal muscle of the embryo...
, they have more favorable clinical behavior and prognosis than classic embryonal rhabdomyosarcoma.
Treatment
Treatment for rhabdomyosarcoma consists of chemotherapyChemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
, radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
and sometimes surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
. 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.
Tungsten Alloy and RMS
A study has shown a link between RMS and TungstenTungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
alloy embedded in muscle (e.g. shrapnel).
However, the tungsten alloy contained 6% Nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
and 3% Cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
, which are known carcinogens. A synergistic effect of alloying tungsten with Ni and Co is suggested (i.e. increasing the toxicity relative to either of the pure metals).
External links
- humpath #1956 (Pathology images)
- Rhabdomyosarcoma by Leonard Wexler, MD in the Sarcoma Learning Center
- Ped-Onc Resource Center
- Information about Rhabdomyosarcoma from St. Jude Children's Research Hospital
- http://www.healthsystem.virginia.edu/uvahealth/peds_oncology/rhabdo.cfm