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

• IM (Intramuscular Myxoma)

What is Intramuscular Myxoma? (Definition/Background Information)

• Intramuscular Myxoma (IM) is an uncommon, benign tumor of the soft tissues, mostly occurring within the skeletal muscles of the body. The cause of tumor formation is unknown
• Middle-aged and elderly individuals, usually women, are prone to this condition. The tumor may be painful or painless, appearing as a single small mass (lump) in the large muscles of the body
• The most frequent location of IM is the thigh muscle, followed by the buttocks, shoulder, and arm. The tumor may be diagnosed using a biopsy
• Chemotherapy or radiotherapy is generally not employed, but a surgical removal of the entire tumor, ensures a complete cure
• With treatment, the prognosis for Intramuscular Myxoma is generally excellent

Who gets Intramuscular Myxoma? (Age and Sex Distribution)

• Intramuscular Myxoma is observed with a higher incidence in women, who are in their mid-adult to late-adult phase (40-70 years old)
• However, it has also been reported in a wider age group, from teenage to the very old
• There is no known ethnic or racial preference

What are the Risk Factors for Intramuscular Myxoma? (Predisposing Factors)

The risk factors for Intramuscular Myxoma have not been identified. However, the following conditions are known to be associated with IM:

• Mazabraud’s syndrome - in this syndrome, multiple IM lesions are noted
• McCune-Albright’s syndrome (a bone-related genetic disorder) - may have multiple tumors also

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 Intramuscular Myxoma? (Etiology)

• The exact cause and mechanism of formation of Intramuscular Myxoma is unknown
• It is speculated that they develop from connective tissue (mesenchyme) stem cells, which have differentiated into fibroblast cells that are dysfunctional

What are the Signs and Symptoms of Intramuscular Myxoma?

The signs and symptoms for Intramuscular Myxoma are based on the location of the tumor; all tumors are intramuscular. Some tumors have mild signs and symptoms, while some others may be asymptomatic. The presentations include:

• The benign nodules may grow at a very slow rate and appear as well-defined masses
• These tumors may also cause reduced motion range and discomfort
• They are usually painless, but occasionally can cause pain and tenderness
• The benign IM soft tissue tumors are normally solitary; although, multiple tumors may be present (in which case these are linked to Mazabraud’s syndrome)
• IM mainly occurs in the thigh muscles; other locations observed being the skeletal muscles of the shoulder, buttock, and upper arm (in rare cases)

How is Intramuscular Myxoma Diagnosed?

A diagnosis of Intramuscular Myxoma may involve:

• Physical examination, evaluation of patient’s medical history
• Tissue biopsy for IM, with histopathological studies conducted on a biopsy specimen - the specimen is studied under a microscope by a pathologist, in order to arrive at a definitive diagnosis
• Ultrasound studies of the affected region
• CT scan, MRI scan of the affected region

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 Intramuscular Myxoma?

The complications due to Intramuscular Myxoma may include:

• The quality of life may be affected due to restriction of motion of the affected region
  • Due to formation of the tumor in the thigh muscles, there may be difficulty walking
  • If it forms in the shoulder/arm, then raising one’s arms, folding hands, etc. may be difficult
• Complications due to the presence of associated disorders, such as Mazabraud’s syndrome and McCune-Albright’s syndrome
• Damage of the muscles, vital nerves, and blood vessels, during surgery
• Recurrence of Intramuscular Myxoma after surgery can occur, if the tumor is incompletely excised

How is Intramuscular Myxoma Treated?

The treatment of Intramuscular Myxoma is as follows:

• If there are no symptoms associated with IM, then non-surgical treatment measures may be adopted. However, periodic observations are maintained
• A complete surgical removal results in cure for Intramuscular Myxoma. On a complete surgical excision with clear margins, the recurrence rate for this tumor is very low
• Radiation therapy and chemotherapy are generally not required
• Post-operative care is important: A 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 Intramuscular Myxoma be Prevented?

• Current medical research has not established a way of preventing Intramuscular Myxoma
• Medical screening at regular intervals with scans and physical examinations, are advised for those who have already endured the tumor

What is the Prognosis of Intramuscular Myxoma? (Outcomes/Resolutions)

• The prognosis for Intramuscular Myxoma is excellent with surgical intervention, even though some tumors may be deep-seated
• With complete excision and removal, the recurrence risk of IM is minimized
• Asymptomatic and benign lesions may require no treatment, unless they affect the quality of life

Additional and Relevant Useful Information for Intramuscular Myxoma:

• The Intramuscular Myxoma tumor cells are primarily composed of fibroblasts (a type of cells found in connective tissues) in a myxoid stroma. The stroma is usually hypocellular 
• In spite of its consistently benign nature, an Intramuscular Myxoma lesion has regions of intense cell activity and increased fluid accumulation too. This can lead to a misdiagnosis of a malignant sarcoma, when examined by a pathologist. Hence, the tumor needs extensive sampling, while being processed in the laboratory