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

• Extra-Abdominal Aggressive Fibromatosis
• Extra-Abdominal Desmoid Fibromatosis
• Extra-Abdominal Desmoid Tumour

What is Extra-Abdominal Desmoid Tumor? (Definition/Background Information)

• Desmoid Tumor is benign tumor of the connective tissues that forms in the ligaments and tendons of the body. Even though the tumor is not malignant, it displays local aggression and can invade uncontrollably into the adjoining/surrounding tissues and structures
• Extra-Abdominal Desmoid Tumor is a type of desmoid tumor that occurs outside the abdomen such as in the limbs and shoulders. They may occur at any site in the body, outside of the abdomen
• Extra-Abdominal Desmoid Tumors are observed in older children and adults. They can cause a wide-ranging set of signs and symptoms depending on their location
• The cause of desmoid tumor is general unknown, but several contributory factors that relate to genetic abnormalities, physical trauma, and hormonal issues have been proposed
• The usually recommended treatment for Extra-Abdominal Desmoid Tumor is surgical excision. However, other measures may be necessary due to the infiltrative nature of the tumor
• The prognosis is generally good for small-sized superficial tumors that are detected early. The prognosis of large-sized and/or deep-seated Extra-Abdominal Desmoid Tumors may depend on a set of multiple factors

Who gets Extra-Abdominal Desmoid Tumor? (Age and Sex Distribution)

• The worldwide incidence of desmoid tumor is between 1 in 250,000 to 500,000; although desmoid tumors occurring outside the abdomen is a fairly uncommon condition
• Extra-Abdominal Desmoid Tumors are more common in children than adults; tumors that occur in the abdomen and outside the abdomen are equally distributed in adults after middle-age
• Males and females are both affected
• All racial and ethnic groups are affected and no specific predilection is seen

What are the Risk Factors for Extra-Abdominal Desmoid Tumor? (Predisposing Factors)

The specific risk factors for Extra-Abdominal Desmoid Tumor have not been identified. The condition is believed to arise due to several factors which include:

• Genetic factors: Some tumors are known to be inherited (family history), while some have been associated with Gardner-type familial adenomatous polyposis
• Hormonal factors (related to endocrine system), such as due to the hormone estrogen
• Physical factors: Some studies show that desmoid tumors are associated with trauma due to surgery; or may be caused by irritation
• Sporadic tumors, which do not occur against a background of any associated genetic disorders, are more common

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 Extra-Abdominal Desmoid Tumor? (Etiology)

The exact cause of development of Extra-Abdominal Desmoid Tumor is currently not clearly understood. However, the following observances have been made by research scientists:

• Genetics:
  • In some cases, 30% of the tumor cells seem to show trisomy for chromosome 8 and 20 (or for either of them). Nevertheless, the experts observe that this anomaly may not be a significant factor for tumor formation
  • 85% of the desmoid tumors occurring with no attributed cause (sporadic tumors) show genetic mutations on the CTNNB1 gene; 10-15% show APC gene mutations. The significance of the role of tumor development due to genetic abnormalities is not clearly understood
  • Desmoid tumors associated with familial adenomatous polyposis (Gardner-type) are also known to display APC gene mutations
  • Both APC and CTNNB1 genes are important for cell growth and cell division through the regulation of certain proteins (such as beta-catenin). A mutation in any of these genes can lead to an uncontrolled proliferation of cells resulting in the formation of desmoid tumors
• Some studies report that hormonal influence may play a role in tumor formation and development
• Iatrogenic factors: Trauma due to a surgery is thought to be a most likely cause of tumor formation

What are the Signs and Symptoms of Extra-Abdominal Desmoid Tumor?

Desmoid tumors may remain silently buried in the body tissues and form gradually, before making their presence felt through associated signs and symptoms. They have a potential to cause severe damage to adjoining tissues and organs, with no pain or mild pain.

The signs and symptoms of Extra-Abdominal Desmoid Tumor may include the following:

• The presence of superficial or deep-seated tumors that is firm with size ranging from 5-10 cm. The tumors are generally poorly-circumscribed
• Tumors that occur on the skin or just below the skin display lesser aggression than deep-seated tumors. Extra-abdomen tumors have the potential to occur anywhere in the body
• Common locations include the extremities (arms and legs or limb girdle) and trunk (chest and back)
• Most tumors are solitary, while some are multiple. It can display aggressive invasion to nearby tissues and structures
• Desmoid tumors are generally painful; the pain is caused when the surrounding nerve fibers or muscles are compressed
• In children, it is more common to find tumors just below the skin surface than deep tumors
• Tumors in the pelvis typically do not present any symptoms. They can be slow-growing masses that can be felt by touch. Some are mistaken for ovarian tumors in women
• Tumors in the joints can restrict joint movement (the arm or leg may be affected); if the knee is affected, it can cause walking difficulty (limping)

How is Extra-Abdominal Desmoid Tumor Diagnosed?

Extra-Abdominal Desmoid Tumor may be diagnosed in the following manner:

• Complete physical examination with comprehensive medical and family history evaluation
• Computerized tomography (CT) or magnetic resonance imaging (MRI) scan of the affected region
• Colonoscopy: This test procedure is generally recommended for individuals with desmoid tumors affecting the abdomen, since they are seen to occur in a setting of FAP which has an increased risk for colon cancer
• Tissue biopsy:
  • A biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist 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. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Sometimes, the pathologist may perform additional studies, which may include electron microscopy, immunohistochemical stains, and molecular studies to assist in the 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 Extra-Abdominal Desmoid Tumor?

The complications from Extra-Abdominal Desmoid Tumor may include the following:

• It can cause emotional stress due to concerns of a malignancy
• Rarely, deep-seated tumors can cause neurological symptoms or affect the joints and cause reduced movement range
• Severely infiltrating and aggressive tumors can destroy the surrounding tissues and organs and cause their functional impairment
• Recurrence of the tumor following incomplete tumor removal is commonly observed (20-50% recurrence rate); recurring tumors are shown to display an even more aggressive behavior
• Difficulty in removing the tumor completely due to its local aggression and infiltration

How is Extra-Abdominal Desmoid Tumor Treated?

The treatment of Desmoid Tumor is dependent upon the type of the tumor, the location of the tumor, the stage of the tumor, the health of the individual and many other factors. Often, a multidisciplinary team of healthcare professionals may be required to treat and manage the condition.

The following treatment methods for Extra-Abdominal Desmoid Tumor may be considered:

• The healthcare provider may consider a ‘wait and watch’ approach for tumors that are small, and those do not present pain or other significant signs and symptoms
• Symptomatic treatment of the condition through pain and anti-inflammatory medication
• Use of non-steroidal anti-inflammatory drugs (NSAIDs) is found to be beneficial in some cases, prior to surgery
• Surgical excision and removal of the entire tumor is normally recommended due to its aggressive and invasive nature. However, it is difficult to remove the tumor entirely due to its infiltrative nature. In many cases, multiple surgeries may be required to completely remove Desmoid Tumors
• Radiation therapy: Using high-energy beams, including x-rays, to destroy the tumor
• Chemotherapy: Using the help of drugs to either kill the tumor cells or shrink the tumor
• Hormone therapy drugs may be used to control the growth of tumor cells
• Targeted therapy: Targeted therapy drugs attack the tumor cells in a specific manner.
• Clinical trials: There may be some newer treatment options, currently on clinical trials, which can be considered for some patients depending on their respective risk factors. The tumors that do not respond to any of the above treatment measures may be referred to clinical trials.

Even though surgery may be recommended, in case of the following factors, other (or additional) treatment modalities may be considered:

• Individuals, who are not candidates for invasive procedures
• Recurring tumors showing poor response to surgical excision and removal
• Personal preferences; unwillingness to undergo surgery

Follow-up care with long-term regular screening and check-ups are important and encouraged.

How can Extra-Abdominal Desmoid Tumor be Prevented?

The development of Extra-Abdominal Desmoid Tumor is difficult to prevent. Currently, no specific preventive measures are available to avoid tumor formation.

What is the Prognosis of Extra-Abdominal Desmoid Tumor? (Outcomes/Resolutions)

• Extra-Abdominal Desmoid Tumor is a locally aggressive tumor that is known to infiltrate and destroy the surrounding tissue structures. The prognosis of the tumor may depend on several factors including:
  • Size of the tumor
  • Time of detection
  • Location of the tumor (whether superficial or deep-seated and the specific site)
  • Surgical accessibility
  • Age of the individual
• If the tumor is located superficially and diagnosed early, then the prognosis is generally excellent on a surgical excision and removal of the entire tumor. In such cases, the risk for recurrence is low
• If the tumors are deep-seated in the body and are discovered late, then it can adversely affect the prognosis
• Desmoid tumors occurring against a background of familial adenomatous polyposis may have a poor prognosis
• Local recurrence is commonly noted, but studies point to an incomplete excision and removal of the tumor. Due to infiltrative nature, it is also very difficult to achieve clear and wide margins for a complete surgical excision
• Even though the tumor is benign and no metastasis is noted, rarely deaths have occurred from desmoid tumor, because of their aggressive growth; in such cases, tumors mostly in the head and neck region have been implicated

Additional and Relevant Useful Information for Extra-Abdominal Desmoid Tumor:

• Study reports indicate that about 0.03% of all cancers may be desmoid tumors

The following DoveMed website links are useful resources for additional information:

http://www.dovemed.com/diseases-conditions/cancer/