The Orthoncology Clinic — Dr Srimanth B S
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Patient Awareness · Benign Soft Tissue Tumours

Desmoid Tumour (Aggressive Fibromatosis)

A non-cancerous growth of scar-like tissue that never spreads to other organs, but can invade nearby muscle and nerves — which is why many are safely watched rather than immediately operated on.

Overview

What is a desmoid tumour?

A desmoid tumour — also known as aggressive fibromatosis or desmoid-type fibromatosis — is a benign but locally aggressive growth of fibroblasts arising in the deep soft tissues. It does not metastasise, yet it can grow into muscles, nerves and blood vessels and cause significant pain and loss of function.1

Key point: "Benign" does not mean "do nothing matters". The goal in desmoid care is to control the tumour with the least possible harm — sometimes that means treatment, and often it means careful observation.2,7
Who's Affected

Who gets desmoid tumours and where do they occur?

Age
15–60 yrs

Peak incidence in the 30s

Sex
Female

Slight female predominance

Common sites
Limbs & trunk

Shoulder, chest wall, arms and legs

  • • Extra-abdominal: shoulder girdle, chest wall and the extremities
  • • Abdominal wall: often in young adults, frequently resectable
  • • Intra-abdominal: the mesentery, strongly associated with familial adenomatous polyposis

1,6

Causes

What causes a desmoid tumour?

Desmoid tumours are driven by over-activation of the Wnt/β-catenin pathway. Most tumours that arise on their own carry a CTNNB1 (β-catenin) mutation, which keeps the fibroblasts multiplying when they should stop.1

Inherited forms
  • • APC mutations in familial adenomatous polyposis (FAP)
  • • FAP-related desmoids are typically intra-abdominal
  • • Trauma, surgery and hormonal change may act as triggers
  • • Nothing a patient did or ate causes a desmoid tumour

1,6

Warning Signs

What symptoms should I look out for?

Desmoids usually announce themselves as a firm, deep lump that grows slowly over months. Symptoms depend far more on where the tumour sits than on how large it is.6

A firm, deep, fixed lump
Usually painless at first, felt within muscle rather than under the skin.
Pain or nerve symptoms
Aching, numbness or tingling when the tumour presses on a nerve.
Loss of movement
Joint stiffness or weakness as the tumour infiltrates muscle.
Abdominal symptoms
Bowel obstruction or pressure symptoms with mesenteric desmoids.
Seek a specialist opinion if you have
  • • Any deep lump larger than a golf ball, or one that is growing
  • • A lump that is firm, fixed and sits below the muscle layer
  • • New numbness, weakness or persistent pain over a lump
  • • A previously stable lump that has started to change
Diagnosis

How is a desmoid tumour diagnosed?

MRI — the key investigation
  • • MRI with contrast defines the size of the tumour and its relationship to nerves, vessels and muscle
  • • Shows the characteristic infiltrative, band-like fibrous pattern
  • • The same MRI protocol is repeated at follow-up to judge growth or regression
  • • CT is used for intra-abdominal and mesenteric disease
Biopsy and genetics
  • • A planned core-needle biopsy confirms the diagnosis before any treatment decision
  • • Beta-catenin staining and CTNNB1 mutation testing support the diagnosis
  • • APC testing and a bowel review are considered if familial adenomatous polyposis is suspected
  • • The biopsy track is planned so it can be removed if surgery is later needed
A desmoid can look like a sarcoma on scans, so the diagnosis should be settled with a properly planned biopsy and reviewed with specialist diagnostic guidance before any operation is contemplated.1,7
Treatment

How is a desmoid tumour treated?

Desmoid care has changed considerably. Surgery is no longer the automatic first step; the modern approach starts with active surveillance and escalates only when the tumour grows or causes trouble.2,7

Watchful waiting — the usual first step

  • • About 20% of desmoids shrink on their own
  • • Roughly 50% stay stable with no treatment at all
  • • Guidelines recommend surveillance first for tumours that are neither symptomatic nor threatening vital structures
  • • Clinical review and MRI every 3–6 months for two years, then annually

2,7

When active treatment is needed

  • • Tumours that are clearly progressing on serial MRI
  • • Symptomatic tumours causing pain or functional loss
  • • High-risk locations — head and neck, or the mesentery
  • • Patient preference after a full multidisciplinary discussion

7

Treatment options in detail

1. Surgery
  • • Goal: remove the tumour with minimal functional loss
  • • Best suited to abdominal wall tumours and resectable extra-abdominal lesions
  • • Recurrence 15–30% even with clear margins
  • • Where a limb is involved, planning follows the same principles as limb salvage surgery

3

2. Radiotherapy
  • • Used after incomplete removal, or for unresectable disease
  • • Dose kept at ≤56 Gy to limit toxicity
  • • Trade-off: fibrosis and joint stiffness in the treated area
  • • Delivered alongside our radiotherapy partners

2

3. Percutaneous ablation
  • • Cryoablation: an ice ball is created through a needle to destroy tumour cells; the ablation zone is visible in real time and pain levels are lower — 80–90% local control in reported series
  • • Radiofrequency ablation: heat generated by a high-frequency current; a day-case procedure with a 75–85% symptomatic response, best for small, accessible lesions
  • • Both are minimally invasive alternatives to open surgery

2

4. Medical therapy
  • • NSAIDs and anti-oestrogens (sulindac, tamoxifen) — older options with variable results
  • • Sorafenib: two-year progression-free survival of 81% versus 36% with placebo, and symptom relief in about 70% of patients
  • • Pazopanib, imatinib and nirogacestat — growing evidence of benefit
  • • Investigational gamma-secretase and CSF1R inhibitors remain in trials
  • • Systemic treatment is coordinated with our medical oncology colleagues

4,5

Why a multidisciplinary team matters

Desmoid decisions are made jointly by orthopaedic oncology, surgical oncology, medical oncology, radiation oncology, radiology, pathology and rehabilitation. Combining the right modalities in the right order is what protects function while still controlling the tumour.6,7

Large, complicated or recurrent desmoids

Why they are challenging
  • • Infiltration of critical structures — nerves and vessels
  • • Pain, joint stiffness and organ compromise
  • • Recurrence of 24–77% after surgery alone

1,3

How recurrence is managed
  • • Repeat surgery or ablation for an isolated recurrence
  • • Radiotherapy after removal for local control
  • • Adding or switching to drug therapy for unresectable or repeatedly recurrent disease
  • • Observation for slow-growing recurrences

2,7

Outlook

What is my outlook with a desmoid tumour?

Spontaneous regression
20%
Tumours that shrink without any treatment
Stable without treatment
~50%
Remain unchanged under surveillance
5-year progression-free
>50%
With modern medical therapy

Desmoid tumours are not fatal, though they can be disabling if left poorly controlled. Quality of life improves markedly once symptoms are controlled and function is preserved — which is why the least harmful effective option is always preferred.2,6

Decision Guide

Which approach is right for me?

Watchful waiting if…
  • • The tumour causes no symptoms
  • • It is not close to nerves, vessels or vital organs
  • • Serial MRI shows it is stable or shrinking
Ablation or surgery if…
  • • The tumour is small and accessible — ablation is often enough
  • • It sits in the abdominal wall or is cleanly resectable
  • • Symptoms persist despite a period of observation
Drug therapy if…
  • • The tumour is unresectable or in a high-risk location
  • • It has recurred more than once
  • • Surgery would cost more function than the tumour itself
Follow-up

What follow-up will I need?

Monitoring plan
  • • First two years: clinical review and MRI every 3–6 months
  • • After two years: annual review if the tumour is stable
  • • The same MRI protocol each time, so changes are directly comparable
  • • Earlier review for any new pain, growth or nerve symptom

2,7

Living well alongside a desmoid
  • • Physiotherapy to protect joint movement and muscle strength
  • • A clear pain-management plan rather than enduring symptoms
  • • Bowel screening where familial adenomatous polyposis is suspected
  • • Normal activity is encouraged unless a specific structure is at risk

6

Next Steps

Next Steps — Talk to a Specialist

Book an AppointmentContact the clinic
Sources

References

  1. 1Kasper B, Baumgarten C, Garcia J, et al. An update on the management of sporadic desmoid-type fibromatosis: a European Consensus Initiative. PubMed, 2017.
  2. 2Desmoid tumours: current management, observation strategies and image-guided ablation. NCBI PMC, 2018.
  3. 3Surgical management and recurrence patterns in desmoid-type fibromatosis. NCBI PMC, 2014.
  4. 4Sorafenib improves progression-free survival for patients with desmoid tumors — trial results. National Cancer Institute, 2018.
  5. 5Gounder MM, Mahoney MR, Van Tine BA, et al. Sorafenib for advanced and refractory desmoid tumors. N Engl J Med. 2018;379(25):2417–2428. PubMed.
  6. 6Kasper B, Ströbel P, Hohenberger P. Desmoid tumors: clinical features and treatment options for advanced disease. The Oncologist, 2011. NCBI PMC.
  7. 7The Desmoid Tumor Working Group. The management of desmoid tumours: a joint global consensus-based guideline. PubMed, 2020.
Medical Disclaimer

Important Notice: This information is provided for educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. It should not be used to diagnose or treat any health condition.

Always seek the advice of a qualified orthopaedic oncologist or healthcare provider with any questions about desmoid tumours or any other medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here.

Treatment varies with the site, size and growth rate of the tumour, the symptoms it causes and the structures it involves. Individual outcomes differ, and decisions are best made within a multidisciplinary team.

The Orthoncology Clinic is committed to providing current, evidence-based information while emphasising multidisciplinary collaboration for complex tumour management.