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Locally aggressiveFAP / sporadicICD-10 D48.1

Desmoid tumour

Aggressive fibromatosis ยท desmoid fibromatosis ยท musculoaponeurotic fibromatosis

Desmoid tumours are locally aggressive monoclonal fibroblastic proliferations that do not metastasise but cause significant morbidity through infiltrative growth. They are classified as sporadic (~85%; somatic CTNNB1 mutation) or FAP-associated (~15%; germline APC mutation). Their unpredictable behaviour โ€” with spontaneous regression in some, indolent stability in many, and aggressive progression in others โ€” has shifted management away from radical surgery toward active surveillance, systemic therapy (sorafenib, nirogacestat, doxorubicin) and selective intervention through a specialist sarcoma MDT.

CurrentLast reviewed 18 May 2026

Epidemiology

  • Incidence ~5-6 per million / year in UK; sporadic predominant.
  • ~15% are FAP-associated (germline APC).
  • Female > male (3:1 in non-FAP).
  • Peak age 30-40 years.
  • Triggers: pregnancy, trauma, surgery (especially in FAP), hormones.

Biology

  • Monoclonal fibroblastic / myofibroblastic proliferation.
  • Wnt / ฮฒ-catenin pathway activation:
    • Sporadic: somatic CTNNB1 mutation (T41A, S45F, S45P).
    • FAP-associated: germline APC mutation โ†’ loss of ฮฒ-catenin degradation.
  • S45F mutation carries worse prognosis with higher recurrence.
  • Hormonal (oestrogen) and inflammatory signals modulate growth.
  • No metastatic potential; locally invasive only.

Anatomical sites

  • Extra-abdominal (35-50%):
    • Shoulder, neck, chest wall, paraspinal, gluteal, thigh.
    • Common after trauma.
  • Abdominal wall (25-30%):
    • Post-pregnancy / post-laparotomy.
    • Rectus muscle, oblique muscles.
  • Intra-abdominal / mesenteric (15-20%):
    • Particularly FAP-associated.
    • Mesentery, retroperitoneum.
    • Major morbidity / mortality cause in FAP (bowel obstruction, fistula, vascular compromise).

Clinical features and imaging

  • Firm, slowly-enlarging mass; often painless initially.
  • Pain develops with infiltration / size.
  • Functional impairment based on site.
  • FAP: often multiple, post-colectomy.
  • MRI: hyperintense T2 with infiltrative margins; characteristic but non-specific.
  • CT: soft-tissue mass; useful for surgical planning.
  • Core / incisional biopsy with ฮฒ-catenin IHC and CTNNB1 / APC sequencing.
  • Histology: bland spindle cells in collagenous stroma; ฮฒ-catenin nuclear positivity.

Management

  • Active surveillance โ€” first-line:
    • Many lesions stable or regress.
    • Serial MRI every 3-6 months for 1-2 years, then annually.
    • Symptom-led intervention if growth / pain / function compromise.
  • Systemic therapy:
    • Sorafenib โ€” multikinase inhibitor with phase 3 evidence; UK use should be confirmed through the sarcoma MDT / specialist commissioning route rather than cited to a NICE TA.
    • Nirogacestat โ€” ฮณ-secretase inhibitor with phase 3 evidence; NICE appraisal GID-TA11559 / ID6453 is in development, with draft guidance published in 2026 and no final positive recommendation at this review date.
    • Tamoxifen / toremifene โ€” hormonal; some response.
    • Doxorubicin-based chemotherapy โ€” for symptomatic / aggressive disease.
    • Methotrexate + vinblastine โ€” alternative.
  • Radiotherapy: 50-56 Gy fractionated; reserved for unresectable / recurrent.
  • Surgery:
    • No longer first-line.
    • Indicated for life-threatening complications (mesenteric vascular compromise).
    • Wide local excision with negative margins; high recurrence even with R0 (20-40%).
    • Avoid in FAP unless mandatory โ€” surgery triggers further desmoids.
  • FAP considerations:
    • Annual abdominal MRI surveillance.
    • Multidisciplinary management โ€” clinical genetics, GI, sarcoma MDT, plastic surgery.
    • Avoid trauma-provocative surgery (delay reconstructive procedures).
  • Specialist sarcoma centre referral recommended for all desmoids (NICE CSG9 / NHSE sarcoma service specification).

References

  1. Kasper B et al. An update on the management of sporadic desmoid-type fibromatosis: a European Consensus Initiative. Ann Oncol. 2017;28:2399-2408.
  2. Gounder MM et al. Sorafenib for advanced and refractory desmoid tumors (Alliance A091105). N Engl J Med. 2018;379:2417-2428.
  3. Gounder MM et al. Nirogacestat, a ฮณ-secretase inhibitor, for desmoid tumors (DeFi). N Engl J Med. 2023;388:898-912.
  4. NICE. Improving outcomes for people with sarcoma (CSG9). London: NICE; 2006.
  5. NICE GID-TA11559 / ID6453. Nirogacestat for treating desmoid tumours. In development; expected publication 2026.
  6. NHS England. Sarcoma service specification. London: NHSE; 2022.

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