Desmoid Tumour (Aggressive Fibromatosis)

A desmoid tumour is a rare growth of fibrous tissue arising in the connective tissue of the abdominal wall, inside the abdomen or in the limbs, shoulder girdle and chest wall. It does not spread to other parts of the body, so it is not a cancer in the usual sense.

It can, however, grow into neighbouring structures and cause pain and loss of function, and it often returns after surgery. Its behaviour is unpredictable: many desmoids stop growing or shrink without treatment. For that reason expert guidelines now advise watching first, not operating.

Symptoms

• A firm, deep lump, often painless at first
• Pain or aching as it presses on muscle or nerves
• Restricted movement of a nearby joint
• Tingling or weakness if a nerve is involved
• Abdominal pain, bloating or bowel obstruction with tumours inside the abdomen
• A lump in the abdominal wall appearing during or after pregnancy, or in a surgical scar

Causes and risk factors

Most sporadic desmoids carry a mutation in the CTNNB1 (beta-catenin) gene within the tumour cells. About one in ten occur in people with familial adenomatous polyposis, caused by an inherited APC gene variant, and these usually develop inside the abdomen, often after bowel surgery. Oestrogen exposure appears to play a part, since many cases arise in women during or after pregnancy. Previous surgery or injury at the site is another recognised trigger.

How it is diagnosed

• MRI: The preferred scan for size, extent and follow-up. Signal changes give clues to how active the tumour is.
• Core needle biopsy: Required to confirm the diagnosis and exclude a sarcoma. Pathology should be read by a soft tissue specialist.
• Mutation testing: CTNNB1 analysis supports the diagnosis. If it is absent, the APC gene and a colonoscopy are considered to look for polyposis.
• CT: Used for tumours inside the abdomen and the mesentery.

Treatment options

• Active surveillance: The first step for most patients: MRI at one to two months, then every three to six months. A half or more remain stable or regress.
• Systemic treatment: For tumours that grow, cause symptoms or threaten organs. Options include sorafenib, pazopanib, the gamma secretase inhibitor nirogacestat, and low-dose methotrexate with vinblastine or liposomal doxorubicin.
• Cryoablation: Image-guided freezing for suitable tumours outside the abdomen, available in specialist centres.
• Surgery: Now reserved for selected situations, such as abdominal wall tumours, where removal is straightforward and would not leave disability.
• Radiotherapy: Considered for progressing tumours where surgery would be mutilating and drugs have failed, mainly in older adults.
• Pain management and physiotherapy: Important throughout, as pain is often the main burden.

When it is urgent

Severe abdominal pain with vomiting and a swollen abdomen may mean bowel obstruction and needs emergency care locally. Rapid growth, new weakness or numbness in a limb, or a swollen leg should be reviewed promptly by your treating team.

Travelling to Türkiye for treatment

The most valuable thing a rare tumour centre offers is often the advice not to operate. A remote review of MRI scans and pathology by a sarcoma team is a sound first step, and travel is needed only if you then require a treatment unavailable at home, such as cryoablation or a specific drug. Surveillance scans and long-term tablets are best coordinated locally. Be cautious if surgery is proposed as the first and only option without discussion of observation.

Send your reports, scans and a short history and a Clinic-Y coordinator replies within 24 hours with suitable teams and written, all-inclusive proposals side by side. Reviewing your case is free.

Frequently Asked Questions