Desmoid

Michael P. Federle, MD, FACR

Kathleen E. Jacobs, BA

Key Facts

Terminology

Imaging

Abdominal desmoids can be solitary or multiple
Tend to invade locally and recur and grow very rapidly, especially in Gardner syndrome
Mesenteric desmoids
- ± displacement, retraction, compression of bowel loops and mesenteric vessels
- ± infiltration into adjacent organs and musculature
Abdominal wall desmoids
- Involve rectus or oblique muscles (incision sites)
- Usually solid with well-defined margins

Top Differential Diagnoses

Clinical Issues

Usually associated with Gardner syndrome
- 18-20% of patients with Gardner syndrome develop desmoids
Most often in women of childbearing age
- 75% of patients with desmoid tumors have had prior abdominal surgery
Encasement of mesentery and bowel → ischemia and obstruction → progressive resection of bowel → short gut syndrome → small bowel transplantation

(Left) Axial CECT in a 35-year-old man with Gardner syndrome who had a colectomy at age 30 shows the suture line

for the ileoanal pouch that was anastomosed to the anus. (Right) Axial CECT in the same patient shows a small soft tissue density mesenteric mass

, a typical desmoid in this setting. This caused no symptoms and was not resected.

(Left) Axial CECT in the same patient 8 months later shows rapid growth of the mesenteric desmoids

. Note the encasement of the mesenteric vessels

. (Right) Axial CECT in the same patient shows the mesenteric desmoid encasing mesenteric vessels

and the bowel. The patient was treated with complete resection of the small bowel and mesentery followed by small bowel transplantation.

TERMINOLOGY

Synonyms

Definitions

Rare, benign, locally aggressive, nonencapsulated tumor of connective or fibrous tissue

IMAGING

General Features

Best diagnostic clue
- Small bowel mesentery or abdominal wall mass arising from scar of prior surgery
Location
- Abdominal
  - Mesentery: Small bowel (most common)
  - Musculature: Rectus, internal/external oblique, psoas, pelvic (rare)
  - Retroperitoneum
- Extraabdominal
  - Bladder, ribs, and pelvic bones
Size
- Mass may range from 4-20 cm
Morphology
- Well- or ill-defined, tan or white, hard fibrous mass
  - Clear, lobulated margin (75%); ill-defined, infiltrative (25%)
Key concepts
- Abdominal desmoids can be solitary or multiple
- Locally aggressive mesenteric primary tumor
- Tend to arise in musculoaponeurotic planes
- Tend to invade locally and recur and grow very rapidly, especially in Gardner syndrome
- May involve bowel loops, bladder, ribs, pelvic bones
- Sometimes classified as low-grade fibrosarcoma or subgroup of fibromatosis
- Usually associated with Gardner syndrome
  - Familial polyposis coli, osteomas, dental defects, congenital pigmented lesions of retina
  - Epidermoid (sebaceous) cyst and fibromas of skin
  - Periampullary, adrenal, thyroid, and liver carcinomas
- 75% of patients with desmoid tumors have had prior abdominal surgery
- 18-20% of patients with Gardner syndrome develop desmoids
  - Accounts for 45% of fibrous lesions in Gardner