Abdominal Wall Fibromatosis

An axial T2W MR image of a 32-year-old woman shows a large well-defined heterogeneous mass in the anterior abdominal wall involving the right rectus abdominis. There are a few linear band (arrowheads) of low signal intensity with in the mass, which are seen in all pulse sequences.

Facts:

• Also known as abdominal desmoid
• Predilection to develop in women of child-bearing age (usually 20-30 years)
• Mass in abdominal wall typically develops following pregnancy
• Most common muscle involved: rectus abdominis, internal oblique
• Some of the masses have estrogen receptor
• May be seen as a manifestation of Gardner's syndrome
• Rx = surgical removal but recurrence rate 15-40%

Imaging Findings

• Heterogeneous intramuscular mass (well- or ill-defined)
• Non-enhancing bands of low signal within the mass on all pulse sequences (probable fibrosis)
• Linear fascial extension "fascial tail sign"

Reference:

Kransdorf MJ, Murphy MD. Imaging of soft tissue tumors, 2nd ed, 2006.