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Mammary-Type Myofibroblastoma

Last updated Nov. 13, 2018

Approved by: Maulik P. Purohit MD, MPH

Mammary-Type Myofibroblastoma (MTMF) is a benign soft tissue tumor that involves the mesenchyme.

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

  • Mammary-Type MFB
  • Mammary-Type Myofibroblastoma of Soft Tissue
  • MTMF (Mammary-Type Myofibroblastoma)

What is Mammary-Type Myofibroblastoma? (Definition/Background Information)

  • Mammary-Type Myofibroblastoma (MTMF) is a benign soft tissue tumor that involves the mesenchyme. The mesenchymal tissue is the source for bone, muscle, connective tissue, and dermis of skin
  • These tumors are histologically similar to myofibroblastoma of breast (or the mammary gland), and hence, they are known as Mammary-Type Myofibroblastoma. MTMF is observed to arise along the natural milk lines of the body, which runs from the armpits to groin
  • Mammary-Type Myofibroblastoma tumors are mostly seen in the pelvis of middle-aged and older adults. They are generally painless and may remain undetected due to a lack of significant signs and symptoms
  • Mammary-Type Myofibroblastoma does not cause any significant sign or symptom, unless a large-sized tumor starts compressing adjoining organs. It may be diagnosed through imaging studies and a tissue biopsy
  • The treatment of choice is a surgical removal of the entire tumor. The prognosis of Mammary-Type Myofibroblastoma is excellent with appropriate treatment

Who gets Mammary-Type Myofibroblastoma? (Age and Sex Distribution)

  • Mammary-Type Myofibroblastoma is generally present in adults with age ranging from 35-86 years; average age of presentation is 56 years
  • The tumors have been observed both in males and females. Some studies indicate that there is a male predominance of 4:1 (male to female ratio)
  • There is no geographical, racial, or ethnic preference noticed

What are the Risk Factors for Mammary-Type Myofibroblastoma? (Predisposing Factors)

  • No specific risk factors are evident for Mammary-Type Myofibroblastoma
  • It is believed that certain hormonal factors may play a role in tumor 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 Mammary-Type Myofibroblastoma? (Etiology)

The exact cause of Mammary-Type Myofibroblastoma occurrence is unknown.

  • Some research studies indicate that the tumor formation may occur due to change of hormonal status in the body
  • The tumors are known to arise along the natural milk lines (also known as the ventral epidermal ridges) of the body, which runs from the armpits to the groin region
  • Partial monosomy, or an anomaly when a part of the chromosome is missing, is observed in some studies
  • MTMF is also shown to be related to two benign tumors, namely cellular angiofibroma and spindle cell lipoma, on tumor cell genetic study

Currently, research is being performed to understand the relevant causative factors.

What are the Signs and Symptoms of Mammary-Type Myofibroblastoma?

The signs and symptoms of Mammary-Type Myofibroblastoma include:

  • MTMF tumors are well-circumscribed, hard, and firm; they may move around the region when touched
  • Most tumors form in the pelvic or groin region; near the testicles in males and near the vagina in females
  • The tumor size can range from 8 mm to 13 cm, with an average size of 5.5 cm; some may grow to large sizes. In some cases, there may be pain from the tumor
  • In rare cases, the tumors may be buried deep in the body; though most are found to form subcutaneously
  • Mostly these tumors appear as painless masses, due to which these are usually detected incidentally; they could go unnoticed for years
  • Signs and symptoms may be observed when large tumors compress and restrict the surrounding organs
  • Other tumor locations include the buttocks (around the anus), abdominal wall, back, shoulder, neck, and behind the kneecap

How is Mammary-Type Myofibroblastoma Diagnosed?

Mammary-Type Myofibroblastoma diagnosis may involve the following tools:

  • Complete physical examination with thorough evaluation of medical history
  • Ultrasound, CT, MRI scans of the affected region: Imaging studies are not known to be particularly useful in analyzing the tumor
  • Tissue biopsy: A tissue biopsy is performed and sent to a laboratory for a pathological examination, who examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

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 Mammary-Type Myofibroblastoma?

The possible complications of Mammary-Type Myofibroblastoma include:

  • Emotional stress and concern, especially with tumors in the genital region
  • Damage of vital nerves, blood vessels, and surrounding structures, during surgery to remove MTMF

How is Mammary-Type Myofibroblastoma Treated?

Following are the treatment methods adopted for Mammary-Type Myofibroblastoma:

  • The healthcare provider may recommend a ‘wait and watch’ approach for small-sized tumors presenting mild signs and symptoms
  • Complete excision and removal of the tumor is normally sufficient treatment. A risk of tumor recurrence is not noted
  • Follow-up care with regular screening and check-ups are important

How can Mammary-Type Myofibroblastoma be Prevented?

Current medical research has not established a way of preventing Mammary-Type Myofibroblastoma.

What is the Prognosis of Mammary-Type Myofibroblastoma? (Outcomes/Resolutions)

  • The prognosis of Mammary-Type Myofibroblastoma is generally excellent on surgical excision and removal of the tumor. It is a benign tumor with no recurrence risk
  • However, periodic follow-up check-ups with screening may be required

Additional and Relevant Useful Information for Mammary-Type Myofibroblastoma:

Please visit our Cancer & Benign Tumor Health Center for more physician-approved health information:


What are some Useful Resources for Additional Information?

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Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 22, 2016
Last updated: Nov. 13, 2018