Fact-sheet: Deep fibromatosis - desmoid tumor


Updated on 09/27/2024 at 3:56 PM

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Definition

Tumor of intermediate malignancy characterized by the disorderly proliferation of monoclonal fibroblasts and myofibroblasts within a collagenous stroma, presenting two types:

  • sporadic with beta-catenin mutation
  • with germline mutation of the APC gene associated with polyposis in the setting of Gardner syndrome

Clinical features

Slow-growing tumor, thus often large in size

Triggering factors: pregnancy, trauma

Occurs mainly in young adults

  • Abdominal wall form, more common in women after pregnancy or on a surgical scar
  • Extra-abdominal form: shoulder, chest wall, thigh. Multifocal in 5-15% of cases
  • Intra-abdominal form: see specific fact sheet on mesenteric desmoid tumor

Some are stable or regress spontaneously while others are aggressive and recurrent

No metastasis

Ultrasound

Poorly defined hypoechoic mass with posterior acoustic shadowing and possible hypervascularity

CT

Relatively homogeneous soft tissue mass, occasionally focally dense relative to surrounding tissues, enhancing after IV administration of iodinated contrast material.

MRI

Reference examination

Abdominal wall desmoid tumor: poorly defined, heterogeneous, infiltrative abdominal wall tumor, with a fibrous component and a hypercellular component

Extra-abdominal desmoid tumor:

  • intermuscular mass frequently infiltrating muscles, more or less well defined, with a frequent fascia tail sign = linear extension of the lesion along the fascia.
  • fibrous components hypointense on T1 and T2, with minimal enhancement,
  • hypercellular components hypointense on T1, hyperintense on T2, enhancing,
  • rare calcifications, possible hemosiderin deposits and myxoid changes

Nuclear medicine

Extra-abdominal desmoid tumor:

  • do not take up 67Ga-citrate
  • take up 99mTc-DMSA
  • FDG-PET: hypermetabolism with median SUVmax of 4.1 [1-8.1]

Management

NetSarc+ tumor board

Therapeutic options:

  • Surveillance
  • Medical treatment
  • Cryotherapy
  • Surgery but frequent recurrence

Differential diagnosis

The mesenteric location of desmoid tumor is discussed in a dedicated fact sheet: Mesenteric desmoid tumor

Carcinoid tumor