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Alveolar Rhabdomyosarcoma (ARMS)

Last updated April 13, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Nephron

Intermediate magnification micrograph of an alveolar rhabdomyosarcoma, H&E stain.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Monomorphous Round Cell Rhabdomyosarcoma
  • Rhabdomyoblastoma
  • Rhabdomyopoietic Sarcoma

What is Alveolar Rhabdomyosarcoma? (Definition/Background Information)

  • Alveolar Rhabdomyosarcoma (ARMS) is an infrequent, but highly malignant ‘skeletal muscle’ tumor of the soft tissues
  • The tumors are poorly-defined masses of round cells resembling lymphomas (types of blood cancer), developing deep within the body tissues, or sometimes below the skin surface. They occur due to inherited or random gene mutations
  • Young adults and adolescents are highly prone to this type of soft tissue sarcoma
  • The common locations for this tumor are the limbs, spinal cord, and pelvic region, followed by the urogenital area. Other not so frequent locations include the skin and abdomen

Who gets Alveolar Rhabdomyosarcoma? (Age and Sex Distribution)

  • Alveolar Rhabdomyosarcoma is observed in all ages; but, most cases are noticed in adolescents, teenagers, and young adults. Young children, infants, and newborns are hardly affected
  • Both male and female genders are at equal risk
  • There is no ethnic/racial preference noticed

What are the Risk Factors for Alveolar Rhabdomyosarcoma? (Predisposing Factors)

Alveolar Rhabdomyosarcoma risk is thought to be linked to the following factors and disorders:

  • Inherited genetic defects
  • Use of drugs like cocaine, marijuana by the parent mother
  • Carcinogens (some have been found on mice and certain types of fish)
  • Beckwith-Wiedemann syndrome
  • Costello syndrome
  • Li-Fraumeni syndrome
  • Neurofibromatosis (type) 1
  • Noonan syndrome

The body physiological conditions, a regular lifestyle, or environmental factors, do not play any role in Alveolar Rhabdomyosarcoma development.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Alveolar Rhabdomyosarcoma? (Etiology)

The cause and mechanism of Alveolar Rhabdomyosarcoma formation is unknown.

  • The rapidly forming and acutely infiltrative tumor is said to arise from embryonic connective tissues responsible for skeletal muscle development
  • It is suspected that either inherited genetic defects or de novo (sporadic and spontaneous) genetic mutations may be the causative factors
  • Translocation (exchange) of chromosome 1 and chromosome 2, with chromosome 13 leading to the formation of a cancer-causing fusion gene (termed as oncogene), and/or an inactive tumor suppressor gene has been observed. These changes are said to cause damage to the DNA, leading to ARMS formation. The exact process how the tumor develops is not clearly understood
  • Hereditary forms of the disorder might be associated with any of the conditions such as; Beckwith-Wiedemann syndrome, Costello syndrome, Li-Fraumeni syndrome, Neurofibromatosis (type) 1, and Noonan syndrome. Nevertheless, these hereditary forms (termed syndrome-associated ARMS) are said to account for only a few percentage of the total number of cases

What are the Signs and Symptoms of Alveolar Rhabdomyosarcoma?

The presentations are based on the location of ARMS. Signs and symptoms of Alveolar Rhabdomyosarcoma include:

  • In the initial growing phase of the tumors, they are normally asymptomatic
  • As the tumor grows rapidly, its presence is felt by pain and a sensation of mass. The mass can cause compression on the body region, resulting in obstruction of adjacent organs
  • Most lesions occur on the hands and feet, region around the spine, nose, and pelvis, followed by urinary and genital region (bladder, vagina, and testes). Occasionally, it is found in the abdomen and under the skin too
  • Some of the symptoms noted are: Bulging of the eyes, double vision, deafness (on the side where lesion is present), inflammation of nasal cavity (sinusitis), nosebleeds, congestion, headaches, vomiting, constipation, blocked urinary bladder, scrotal mass, blood/fluid discharge from vagina, yellowing of the eyes (jaundice)
  • Functional impairment of organs due to mass effect

How is Alveolar Rhabdomyosarcoma Diagnosed?

Alveolar Rhabdomyosarcoma is diagnosed by:

  • Physical examination, evaluation of patient’s medical history
  • Histopathological studies conducted on a biopsy specimen. High cell variations and many stages of morphological genesis can be observed
  • Ultrasonography of the affected region
  • CT, MRI scan of the affected region
  • Whole-body PET scan, bone scan of the affected region to check for tumor metastasis. This helps with the staging of the tumor

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Alveolar Rhabdomyosarcoma?

Complications from Alveolar Rhabdomyosarcoma could include:

  • Complications are dependent on the site and stage of the tumor. It is easier to treat the primary tumor; but if metastasis occurs, treatment can be challenging
  • Metastasis affects bones (bone marrow) and lungs causing symptoms such as, cranial nerve/nerve root anomalies, breathing difficulty, anemia, fluid in the space around lungs, low blood count, frequent infection, bleeding, etc.
  • Damage to vital nerves, blood vessels, and surrounding structures during surgery
  • Side effects from chemotherapy (such as toxicity), radiation therapy (radiation fibrosis)

How is Alveolar Rhabdomyosarcoma Treated?

Treatment measures for Alveolar Rhabdomyosarcoma include the following:

  • Wide surgical excision of ARMS with removal of the entire lesion; which is followed by radiation and a course of intensive chemotherapy. This is the standard treatment protocol
  • If possible, sometimes chemotherapy/radiotherapy is given prior to the operation, to shrink the tumor
  • Arterial embolization of the tumor is used to provide temporary relief from the symptoms, and reduce blood loss during ‘tumor removal’ surgical procedure
  • When ARMS is at an inaccessible location, or is unsafe for a surgical intervention; non-invasive procedures are adopted
  • Post-operative care is important. Minimum activity level is to be ensured until the surgical wound heals
  • Follow-up care with regular screening and check-ups are important

How can Alveolar Rhabdomyosarcoma be Prevented?

  • Current medical research have not established a way of preventing Alveolar Rhabdomyosarcoma
  • Genetic counseling and testing: If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • The presence of any tumor or lesion should be immediately informed to the physician
  • Regular medical screening at periodic intervals with blood tests, scans, and physical examinations are mandatory for those who have already endured ARMS; due to its metastasizing potential and chances of recurrence. Often several years of active vigilance is necessary

What is the Prognosis of Alveolar Rhabdomyosarcoma? (Outcomes/Resolutions)

  • Alveolar Rhabdomyosarcomas are rare, but highly malignant tumors
  • The long-term prognosis may depend on a combination of factors such as the: Age of the individual, tumor stage at detection, size, type, and location of the tumor, and whether it has spread around the area, or to other distant locations (particularly to the lymph nodes and distal areas)
  • The long-term outcome is grim with metastases for most individuals (with a 15% survival rate)

Additional and Relevant Useful Information for Alveolar Rhabdomyosarcoma:

  • Amongst pediatric soft tissue sarcomas (affecting children less than 15 years), rhabdomyosarcomas form the largest category
  • Embryonic, Alveolar, and Pleomorphic Rhabdomyosarcoma are the 3 types of rhabdomyosarcoma. About 20-30% of rhabdomyosarcoma tumors are the alveolar type

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 30, 2013
Last updated: April 13, 2018