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Pleomorphic Rhabdomyosarcoma (PRMS)

Last updated Dec. 23, 2018

Approved by: Maulik P. Purohit MD, MPH

Pleomorphic Rhabdomyosarcoma (PRMS) is an extremely infrequent, but highly malignant ‘skeletal muscle’ tumor of the soft tissues.

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

  • Anaplastic Rhabdomyosarcoma and Undifferentiated Sarcoma
  • PRMS (Pleomorphic Rhabdomyosarcoma)

What is Pleomorphic Rhabdomyosarcoma? (Definition/Background Information)

  • Pleomorphic Rhabdomyosarcoma (PRMS) is an extremely infrequent, but highly malignant ‘skeletal muscle’ tumor of the soft tissues
  • It is composed of an unusual mix of round, spindle, and polygonal-shaped cells seen with differentiated skeletal muscles. It may develop deep within the body tissues
  • Middle-aged adults are affected by these soft tissue sarcomas
  • The regular locations for PRMS are the lower and upper limbs. Other not so frequent locations include the chest and abdomen
  • Treatment includes surgical removal of the tumor with radiation & chemotherapy; nevertheless, the long-term outcome is grim (especially if the tumor spreads to other regions)

Who gets Pleomorphic Rhabdomyosarcoma? (Age and Sex Distribution)

  • Even though Pleomorphic Rhabdomyosarcoma is observed across all ages; a majority of them are noticed in adults over 40 years, with a peak in the 50-60 year age range. Young children are hardly affected
  • Males are affected more than females
  • There is no ethnic/racial preference noticed

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

The risk is thought to be linked to inherited genetic defects, or to those defects that develop spontaneously. The body physiological conditions, a regular lifestyle, or environmental factors, do not play any role in Pleomorphic 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 ones 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 Pleomorphic Rhabdomyosarcoma? (Etiology)

  • The cause and mechanism of Pleomorphic 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 agents. Some random mutations of chromosomal anomalies/irregularities have been recorded

What are the Signs and Symptoms of Pleomorphic Rhabdomyosarcoma?

The presentations are based on the location of PRMS. Signs and symptoms of Pleomorphic 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 in the legs (in 45% of the cases) followed by the hands. Occasionally, it is found in the abdomen and on the chest wall too
  • Functional impairment of organs may occur owing to the large size of the tumor (5-15cm), due to mass effect

How is Pleomorphic Rhabdomyosarcoma Diagnosed?

Pleomorphic Rhabdomyosarcoma is diagnosed by:

  • Physical examination, evaluation of patient’s medical history
  • Histopathological studies conducted on a biopsy specimen
  • Ultrasonography the of 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 staging of the tumor

What are the possible Complications of Pleomorphic Rhabdomyosarcoma?

Complications from Pleomorphic 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 may occur within 12-15 months of tumor growth; the metastasis rate is around 55%
  • Recurrence of the tumor post-surgery; recurrence rate is 45% and often happens within a year of surgical excision of the primary tumor
  • Damage to vital nerves, blood vessels, and surrounding structures during surgery
  • Side effects from chemotherapy (such as toxicity), radiation therapy (radiation fibrosis)

How is Pleomorphic Rhabdomyosarcoma Treated?

Treatment measures for Pleomorphic Rhabdomyosarcoma include the following:

  • Wide surgical excision of PRMS with removal of the entire lesion; this is essentially followed by radiation and/or intensive chemotherapy
  • 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 PRMS 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 Pleomorphic Rhabdomyosarcoma be Prevented?

  • Current medical research have not established a way of preventing Pleomorphic 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 PRMS; due to its high metastasizing potential and chances of recurrence. Often several years of active vigilance is necessary

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

  • Pleomorphic Rhabdomyosarcomas are rare, but highly malignant cancers
  • A set of reliable factors for PRMS prognosis have not yet been developed. However, the long-term outcome may depend on a combination of factors such as; 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 regions
  • The long-term outcome is poor with metastases for most individuals (with a 30% survival rate)

Additional and Relevant Useful Information for Pleomorphic 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. Only about 5% of Rhabdomyosarcoma cancers are PRMS, and these occur primarily in adults
  • Pleomorphic Rhabdomyosarcoma has 3 morphological subdivisions: Classic PRMS, Round Cell PRMS, and Spindle Cell PRMS

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: Dec. 23, 2018