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Health condition · Clinically reviewed

Myxofibrosarcoma, a rare limb sarcoma that needs specialist margins.

A slow-growing lump can hide an infiltrative tumour. Early sarcoma-centre referral and wide excision are what keep recurrence rates down.

Jump to treatment
A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE NG161 and specialist sarcoma-centre standards you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK sarcoma-pathway guidance, including MDT-led surgery and radiotherapy planning.

Key facts

Myxofibrosarcoma at a glance.

The essentials, in plain English - what it is, who it affects, and why margins matter so much.

  • What it is

    A rare soft tissue sarcoma of fibroblastic origin, typically arising in the deep or subcutaneous tissues of a limb.

  • Who it affects

    Most common in older adults, often in the sixth to eighth decade, with a slight male predominance.

  • Usual site

    Most often the legs, followed by the arms - usually as a slow-growing lump deep to or within the fascia.

  • Growth pattern

    Infiltrative, with microscopic tumour extensions ("tentacles") reaching well beyond the visible or palpable mass.

  • Key risk

    A high rate of local recurrence, driven by that infiltrative margin rather than by aggressive metastasis in low-grade disease.

  • Mainstay treatment

    Wide local excision with clear margins at a specialist sarcoma centre, often combined with radiotherapy.

Why this guide matters

A rare tumour that punishes a rushed operation.

Myxofibrosarcoma is uncommon, but its behaviour is well understood. The three points below shape everything else on this page.

  • Biopsy before surgery, always

    A core needle biopsy at a sarcoma centre confirms diagnosis and grade before any operation is planned - never the other way round.

  • Margins are everything

    The infiltrative growth pattern means clear margins matter more here than tumour size alone - this drives the surgical approach.

  • Follow-up is long-term

    Local recurrence can appear years after treatment, so surveillance continues well beyond the initial recovery period.

How the diagnosis is made

From first lump to an MDT-led plan.

The steps a UK sarcoma pathway will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Lump assessment in primary care

    A GP examines any soft tissue lump for size, depth, growth rate and fixation to deeper structures.

  2. 02

    Assessing

    Urgent suspected-sarcoma referral

    Per NICE NG161, any lump over 5cm, enlarging, or deep to the deep fascia triggers an urgent referral pathway.

  3. 03

    Assessing

    MRI as first-line imaging

    MRI of the affected limb defines the size, depth and relationship to muscle, nerves and vessels before any biopsy.

  4. 04

    Confirming

    Core needle biopsy at a sarcoma centre

    A specialist-performed biopsy confirms the diagnosis and grade. This must happen before any surgery is planned.

  5. 05

    Confirming

    Staging CT chest

    Because sarcomas can spread to the lungs, a CT chest checks for metastatic disease before treatment begins.

  6. 06

    Preparing

    Regional sarcoma MDT review

    A specialist commissioned multidisciplinary team - surgeons, oncologists, radiologists and pathologists - agrees the treatment plan.

  7. 07

    Preparing

    Surgical planning meeting

    The MDT maps out excision margins and considers whether radiotherapy should come before or after surgery.

Typical timeline: referral to a specialist sarcoma centre within weeks, as recommended by NICE NG161.

Symptoms

What myxofibrosarcoma actually feels like.

A quiet, slow-growing lump that is easy to underestimate. And the features that mean it’s time to get it checked properly.

  • Painless enlarging mass

    The most common presentation - a firm, gradually growing lump that is often noticed incidentally.

  • Mild ache or pressure

    Some tumours cause a dull ache or a feeling of pressure, particularly as they enlarge or press on nearby structures.

  • Limb location

    Most often felt in the thigh, calf, upper arm or forearm, sometimes deep enough to be missed on early examination.

  • Skin changes

    Superficial tumours can cause overlying skin thinning, a bluish tinge, or a fixed, tethered feel.

  • Fixation to deeper tissue

    A lump that does not move freely over muscle or fascia is a more concerning finding than one that slides easily.

  • Mistaken for a benign lump

    Slow growth means it can be dismissed as a lipoma or cyst for months before review, delaying diagnosis.

  • Gradual size increase

    Change over weeks to months, rather than days, is typical - but any change in a longstanding lump warrants review.

  • Red flag - large or deep lump

    Any lump over 5cm, growing, or deep to fascia should be treated as suspicious until proven otherwise.

Treatment

How myxofibrosarcoma is treated in the UK.

Wide surgical excision underpins every plan, with radiotherapy, re-excision and selective chemotherapy layered in as needed.

  • Wide local excision

    Surgical removal with a margin of healthy tissue is the mainstay of treatment, carried out at a specialist sarcoma centre.

  • Re-excision surgery

    Because of the infiltrative growth pattern, a further operation is often needed if initial margins come back involved or close.

  • Pre-operative radiotherapy

    Used in some cases to shrink the tumour and improve the chance of a clear margin before surgery.

  • Post-operative radiotherapy

    Commonly given after surgery given the high local recurrence risk, particularly for larger or deeper tumours.

  • Chemotherapy

    Reserved for high-grade, large, or metastatic disease, usually as part of a wider systemic treatment strategy.

  • Limb-sparing reconstruction

    Plastic or orthopaedic reconstruction after excision aims to preserve limb function wherever possible.

  • Surveillance imaging

    Regular clinical review and MRI follow-up monitor for local recurrence, which can occur even years after treatment.

  • Specialist MDT management

    Ongoing care stays with a regional sarcoma centre, coordinating surgery, oncology and rehabilitation.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist sarcoma-society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your specialist sarcoma team knows your case and imaging and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Suspected cancer: recognition and referral - sarcoma (NG12/NG161).

  • National Cancer Research Institute. Sarcoma clinical guidelines.

  • British Sarcoma Group. Guidelines for the management of soft tissue sarcoma.

  • NHS England. Sarcoma service specification for specialist commissioning.

Red flags

When a lump needs urgent attention.

Most soft tissue lumps are benign. These are the features that shift the balance towards urgent sarcoma referral.

  • Lump over 5cm

    Any soft tissue lump larger than 5cm should be referred urgently under the suspected sarcoma pathway.

  • Deep to fascia

    A lump felt to be beneath the deep fascia, rather than sitting just under the skin, raises suspicion significantly.

  • Rapid or continued growth

    A lump that keeps enlarging, rather than staying static, should not simply be watched.

  • Recurrence after previous excision

    New swelling at or near a prior surgical scar needs prompt sarcoma-centre review, not reassurance alone.

  • New pain in a longstanding lump

    A lump that was previously painless becoming painful can signal growth or nerve involvement.

  • Neurological symptoms

    Numbness, weakness or tingling in the limb suggests possible nerve compression and needs urgent assessment.

  • Skin ulceration or bleeding

    Breakdown of the overlying skin over a soft tissue mass is a marker of advanced local disease.

  • Unexplained weight loss

    Systemic symptoms alongside a growing lump raise concern for more advanced or metastatic disease.

  • Breathlessness or chest symptoms

    Because the lungs are the most common site of spread, new respiratory symptoms warrant prompt investigation.

Living with it

Treatable and manageable, with vigilant follow-up.

Four things that make the biggest difference after treatment - keeping appointments, rebuilding function, staying aware of your limb, and using the support available.

A quiet reminder

Recurrence caught early is far easier to treat.

Sticking with surveillance, even when you feel well, is what protects the outcome long term.

  1. 01 Follow-up

    Keep every surveillance appointment

    Local recurrence is the main risk with this tumour, and it is picked up earliest through scheduled MRI and clinical review.

  2. 02 Function

    Work with rehabilitation early

    Physiotherapy and occupational therapy after limb surgery help rebuild strength and range of movement.

  3. 03 Awareness

    Know your own scar and limb

    Getting used to how your operated limb normally feels makes it easier to notice a genuine change early.

  4. 04 Support

    Ask about sarcoma support services

    Specialist sarcoma nurses and charities offer practical and emotional support through treatment and beyond.

Frequently asked

Everything we get asked about myxofibrosarcoma.

Quick answers on diagnosis, surgery, recurrence and follow-up.

  • What is myxofibrosarcoma?

    It is a rare soft tissue sarcoma arising from fibroblast-like cells, most often found in the limbs of older adults. It typically presents as a slow-growing, often painless mass and is notable for an infiltrative growth pattern that extends microscopically beyond the visible lump.

  • Why does it come back so often?

    Myxofibrosarcoma grows with finger-like microscopic extensions well beyond what can be seen or felt. Even with careful surgery, cells can be left behind at the margin, which is why local recurrence rates are higher than for many other soft tissue tumours.

  • Do I need a biopsy before surgery?

    Yes. NICE guidance and sarcoma-centre practice both require a core needle biopsy to confirm the diagnosis and grade before any surgical planning, because the approach to excision depends on knowing exactly what is being treated.

  • Will I need more than one operation?

    Possibly. Because of the infiltrative margins, a re-excision is common if the first operation does not achieve a fully clear margin. Your sarcoma team will discuss this as part of the initial plan, not as an unexpected setback.

  • Is chemotherapy always needed?

    No. Chemotherapy is usually reserved for high-grade tumours, larger disease, or cases where it has spread. Many people with lower-grade, localised myxofibrosarcoma are treated with surgery and radiotherapy alone.

  • What does follow-up look like?

    Regular clinical examination and MRI of the treated area, continuing for several years, because local recurrence can occur later than with many other cancers. A staging CT chest is also used periodically to check for spread.

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