Fact-sheet: Mesenteric fibromatosis - Desmoid tumor


Updated on 04/24/2020 at 9:53 AM

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Definition

Mesenchymal tumor characterized by infiltrative fibroblastic proliferation.

This is a low-grade soft tissue neoplasm, but one that is prone to recurrence.

Mesenteric desmoid tumors are the most common cause of mesenteric tumors; most cases are sporadic, but 10% occur in the setting of Gardner syndrome.

They occur at a variable age, on average around 35-40 years, affecting men and women equally.

Clinical features

Association with familial adenomatous polyposis in 10% of cases.
Post-surgical onset is suggestive, particularly following cesarean section.

Patients typically present with an asymptomatic, sometimes painful, abdominal mass.
Diagnosis is often made following a complication such as gastrointestinal bleeding, perforation, or ureteral compression.

CT

Tumor size is often substantial: 10 cm or more

Well-circumscribed, well-defined, rounded margins

The appearance of desmoid tumors varies according to their composition (intratumoral collagen density and/or capillary richness)

The lesion may therefore appear iso-, hypo-, or hyperdense relative to muscle

Homogeneous (unless hemorrhagic changes are present)

Contrast enhancement after injection, which may be moderate

Assessment of mass effect on adjacent structures:

  • bowel compression
  • ureteral compression
  • vascular compression, notably with risk of mesenteric ischemia
  • nerve compression
  • venous compression

MRI

Desmoid tumors appear:

  • heterogeneous
  • hypointense or isointense on T1
  • variable signal on T2 depending on the predominant component (cellular or fibrous)
  • markedly hyperintense on STIR
  • intense enhancement after gadolinium injection

Note that when T2 signal is high, the tumor is highly cellular and has greater growth potential.

Differential diagnosis

GIST,
Leiomyoma,
Sarcoma, Fibrosarcoma