Nodular fasciitis, fibromatoses and desmoid tumour
- Lesion
A fast-growing but harmless lump, a scarring disease of palms and soles, and a tumour that invades locally but never spreads.
What it is
Fibroblastic and myofibroblastic tumours range from self-limited to malignant. Nodular fasciitis is a rapidly growing nodule, often on the forearm of young adults, that looks alarming under the microscope but regresses; it is a transient clonal neoplasm with USP6 rearrangements. Superficial fibromatoses are nodular proliferations of myofibroblasts in the palm (Dupuytren), sole (Ledderhose) and penis (Peyronie) that contract tissue. Deep fibromatosis (desmoid tumour) infiltrates muscle and fascia, recurs locally but does not metastasize; it carries CTNNB1 or APC mutations, and is part of familial adenomatous polyposis (Gardner syndrome). Adult fibrosarcoma is now a rare diagnosis of exclusion.
Structure
- Nodular fasciitis: loosely arranged plump fibroblasts with mitoses but no atypia, in a myxoid stroma with lymphocytes and red cells; looks like cells in tissue culture.
- Superficial fibromatosis: nodules of myofibroblasts that mature into dense collagen cords.
- Desmoid: long sweeping fascicles of uniform, bland spindle cells in collagen, infiltrating muscle at the edges.
- Fibrosarcoma: dense herringbone fascicles of atypical spindle cells with many mitoses.
Step by step
- In desmoids, a CTNNB1 mutation or loss of APC stabilizes beta-catenin.
- Beta-catenin enters the nucleus and switches on WNT target genes.
- Myofibroblasts proliferate and lay down collagen, infiltrating muscle and fascia.
- Growth is influenced by hormones and trauma (pregnancy, surgical scars).
- Without metastatic capacity, the tumour harms by local invasion and recurrence.
Fibrous lesions compared
| Lesion | Typical patient and site | Genetics | Behaviour |
|---|---|---|---|
| Nodular fasciitis | Young adults; forearm, trunk | USP6 rearrangement | Self-limited |
| Superficial fibromatosis | Older men; palm, sole, penis | Polygenic risk | Contracture; recurs |
| Desmoid tumour | Young adults; abdominal wall, mesentery, shoulder girdle | CTNNB1 or APC | Locally aggressive, no metastasis |
| Fibrosarcoma | Adults (rare); infants (infantile type) | Complex; ETV6-NTRK3 in infantile | Malignant |
Markers
- Nuclear beta-catenin (desmoid)
- SMA (myofibroblasts)
Clinical notes
- A mesenteric desmoid in a patient with FAP can obstruct bowel and is a major cause of death after colectomy.
- Peyronie disease causes penile curvature and painful erection.
- Fast growth over a few weeks favours nodular fasciitis over a sarcoma.
Test yourself
Think of the answer, then tap the question to see it.
Which gene rearrangement is typical of nodular fasciitis?
USP6.
Which pathway is activated in desmoid tumours?
WNT signaling, through CTNNB1 mutation or APC loss, giving nuclear beta-catenin.
Do desmoid tumours metastasize?
No. They invade locally and recur but do not metastasize.
What are the three sites of superficial fibromatosis?
Palm (Dupuytren), sole (Ledderhose) and penis (Peyronie).
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Dupuytren Contracture (StatPearls (NCBI Bookshelf), 2025); Desmoid tumor: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2025); Soft Tissue Sarcoma Treatment (PDQ®)–Health Professional Version (National Cancer Institute, 2025).
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Representative model, for educational purposes only.