Synonyms

Desmoid-type fibromatosis associated with familial adenomatous polyposis

Category

Soft tissue

Behaviour

Benign

Gender

Both equally

Tissue of Origin

Fibrous

Epidemiology

• Benign fibromatosis in FAP Syndrome
• Peak incidence 2nd-3rd decades
• Abdominal wall predominance in FAP

Clinical Features

• Firm nodular mass
• Often multifocal in FAP patients

Location

• Abdominal wall (most common in FAP)
• Mesentery
• Deep soft tissues

Imaging

MRI: infiltrative Fibrous mass

Pathology

Fibroblasts in fascicles without atypia

Genetics

• Associated with APC mutations (FAP)
• Somatic TP53 mutations in some

Treatment

Observation vs surgical excision depending on symptoms

Prognosis

Benign but may progress without treatment

Key Points

• Benign fibromatosis variant
• Associated with familial adenomatous polyposis

Workup - Blood Tests

No specific blood tests

Workup - Local Imaging

MRI - characterise extent

Workup - Biopsy

Core needle biopsy if diagnosis uncertain

Workup - Staging

No staging required

Workup - Other

• Genetic counselling for FAP
• Surveillance for associated malignancies