Soft-tissue sarcoma

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Soft-tissue sarcoma is a family of more than one hundred mesenchymal malignancies rather than one disease. It may arise anywhere, including limb, trunk, retroperitoneum, head and neck, viscera and skin. The classic lesion is a painless enlarging mass. Referral rules deliberately favour sensitivity because benign lumps vastly outnumber sarcoma and early expert imaging prevents an avoidable unplanned removal.

Ultrasound distinguishes a simple cyst or classic superficial lipoma from a solid, deep or vascular lesion, but indeterminate findings are not a diagnosis. MRI maps tumour, oedema and relation to fascia, nerves, vessels and bone. A radiologist then places multiple core samples through a route agreed with the surgeon. The tract is considered contaminated and removed with the tumour. Fine-needle aspiration alone usually lacks architecture for subtype and grade, while a large open biopsy can contaminate several compartments.

Expert pathology integrates morphology, immunophenotype and subtype-specific molecular tests. Grade, size, depth and margin predict outcome, but biology matters: well-differentiated liposarcoma tends to recur locally, leiomyosarcoma favours blood-borne spread, and some translocation-driven sarcomas have characteristic age and site. A multidisciplinary review must reconcile imaging and tissue; a core labelled benign that does not explain a growing heterogeneous mass requires re-biopsy.

Wide surgery is the curative foundation for resectable local disease. The specimen is removed intact with the biopsy tract and a planned margin, using plastic, vascular, orthopaedic or visceral reconstruction when needed. Radiotherapy improves local control in selected higher-risk tumours. Advanced disease treatment is goal specific: doxorubicin may prolong control, combination treatment may be used when rapid shrinkage could relieve symptoms or enable surgery, and later options depend on histology, molecular targets, prior therapy and funding. Rehabilitation and palliative care run alongside tumour treatment.

Key points

An enlarging lump is the single most important warning feature; lack of pain does not make a soft-tissue mass benign.
Deep location, size above 5 cm, fixation, recurrence and pain increase concern, but a small superficial sarcoma still occurs.
In primary care, urgent ultrasound is the practical first-line test for an unexplained enlarging lump; an uncertain or suspicious study requires direct sarcoma-pathway referral.
MRI with contrast is the preferred local-staging test for a limb or trunk-wall mass and should precede biopsy whenever possible.
The diagnostic reference standard is multiple image-guided core biopsies planned with the sarcoma surgeon so the tract can be excised at definitive surgery.
Do not perform an unplanned excision, transverse incision or drainage of a possible sarcoma; obtain imaging and specialist tissue first.
Pathology should state histological subtype, grade, necrosis, molecular result when relevant and later the size, depth and margin of resection.
CT chest is the first-line metastatic staging test for most high-grade limb and trunk sarcomas because lung spread predominates.
First-line curative treatment for localised adult soft-tissue sarcoma is specialist wide en-bloc resection with a negative margin while preserving function where oncologically safe.
Preoperative or postoperative radiotherapy improves local control for selected intermediate- or high-grade, deep, large or close-margin tumours; timing trades smaller fields against wound complications.
Adjuvant chemotherapy is not automatic. It is considered for selected high-risk, chemosensitive subtypes after an individual benefit and toxicity discussion.
Doxorubicin is a standard first-line systemic option in advanced adult soft-tissue sarcoma; adding ifosfamide may increase response when shrinkage is important but also increases toxicity.
Retroperitoneal sarcoma requires an expert high-volume MDT before biopsy or surgery because subtype and organ relationships determine an en-bloc multivisceral strategy.
Surveillance is risk adapted and includes clinical local assessment plus lung imaging, functional recovery and late radiotherapy and chemotherapy effects.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Mostly sporadic mesenchymal disease

Most adult soft-tissue sarcomas arise without a known cause and encompass many adipocytic, smooth-muscle, fibroblastic, vascular, neural and undifferentiated lineages.

Inherited susceptibility

Li-Fraumeni, neurofibromatosis type 1, hereditary retinoblastoma and other rare syndromes increase selected sarcoma risks and justify genetics assessment when phenotype or family history fits.

Radiation and chronic tissue injury

A sarcoma can arise years after radiotherapy, while chronic lymphoedema predisposes to angiosarcoma and uncommon chemical exposures are linked to particular vascular tumours.

Molecularly defined subtypes

Translocations, amplifications and kinase alterations drive synovial sarcoma, liposarcoma, infantile fibrosarcoma and other entities, influencing diagnosis and sometimes targeted treatment.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Malignant cells grow along tissue planes
Sarcoma expands within a pseudocapsule but microscopic extensions and satellite nodules can remain outside the visible mass, requiring a cuff of uninvolved tissue for clearance.
2
Grade predicts metastatic behaviour
Differentiation, mitotic activity and necrosis generate a histological grade that strongly influences lung-spread risk, radiotherapy use and surveillance intensity.
3
Haematogenous spread predominates
Most limb and trunk sarcomas spread through blood to lung, whereas nodal spread is uncommon except in selected subtypes such as epithelioid, clear-cell and angiosarcoma.
4
Anatomical compartment determines resectability
Tumour relationship to fascia, major nerves, vessels, bone and viscera determines whether wide en-bloc resection preserves useful function or needs complex reconstruction.
5
Retroperitoneal biology differs
Large liposarcoma or leiomyosarcoma may envelop organs before symptoms, and local recurrence can dominate outcomes because generous circumferential margins are anatomically impossible.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Enlarging painless mass

Progressive growth over weeks or months is the most useful clinical signal and warrants imaging even when the lump is mobile and painless.

Deep or large lesion

A mass beneath fascia or around 5 cm or larger has greater malignant probability and requires MRI and specialist assessment rather than office excision.

False haematoma

A lump described as bruising without adequate injury, or one that enlarges instead of resolving, may be a haemorrhagic sarcoma and needs contrast imaging.

Neurovascular threatRed flag

Rapidly increasing pain, weakness, numbness, coolness, absent pulse or tense swelling indicates urgent compartment and vascular assessment.

Retroperitoneal disease

Abdominal fullness, early satiety, flank discomfort, weight loss, hydronephrosis or unilateral leg swelling can reflect a very large occult tumour.

Pulmonary relapse

New cough, dyspnoea or chest pain in a high-grade sarcoma survivor needs prompt chest imaging, although surveillance often finds asymptomatic nodules first.

Red flags requiring action

Any unexplained soft-tissue lump that is increasing in size requires prompt imaging, even when it is painless or initially small.
A mass deeper than investing fascia, larger than about 5 cm, painful, recurrent after excision or fixed to surrounding structures has increased malignant probability.
A presumed haematoma without substantial trauma, anticoagulation or expected interval resolution needs imaging and tissue review rather than repeated aspiration.
A deep intramuscular mass must not be shelled out as a lipoma; MRI and sarcoma-centre biopsy should precede definitive surgery.
A growing abdominal or retroperitoneal mass with early satiety, distension, flank pain, leg oedema or hydronephrosis can be sarcoma despite absent superficial lump.
A sudden increase in pain, neurological loss, bleeding or distal vascular compromise requires same-day specialist assessment.
Local recurrence within or beside a previous scar may extend well beyond the palpable focus and needs restaging before another operation.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line urgent ultrasoundFirst stepFirst line
Why
Determine whether an enlarging superficial lump is cystic, fatty, solid, vascular or deep and identify features requiring referral.
Interpretation and limitations
A confident benign diagnosis must match the history; any indeterminate, vascular, deep or heterogeneous lesion proceeds directly to the sarcoma service rather than serial community scans.
02
Preferred contrast MRIPreferred
Why
Define local tumour extent, fascial compartment, necrosis, oedema and relationship to skin, bone, joints, nerves and vessels before biopsy.
Interpretation and limitations
MRI cannot reliably determine histological subtype, and oedema is not identical to tumour; use it to plan a safely resectable biopsy tract and definitive field.
03
Reference image-guided core biopsy
Why
Provide viable tissue for morphology, grade, immunohistochemistry and molecular testing while preserving future margins.
Interpretation and limitations
Take several cores from enhancing solid tissue, avoid necrosis and major neurovascular structures and place the tract longitudinally within the planned resection; repeat discordant samples.
04
CT chest staging
Why
Identify pulmonary metastases before curative surgery and establish a baseline for high-grade limb and trunk sarcoma surveillance.
Interpretation and limitations
Review indeterminate nodules by size, pattern and interval change; an isolated nodule may need tissue because benign disease and a resectable metastasis have different implications.
05
Abdominal and pelvic staging
Why
Map retroperitoneal anatomy and detect histology-specific abdominal or nodal spread using contrast CT and selected MRI or PET.
Interpretation and limitations
Image the full retroperitoneal tumour and both kidneys and major vessels; routine PET is not a substitute for biopsy or standard chest and local staging.
06
Definitive pathology and molecular classificationDefinitive
Why
Report subtype, grade, size, depth, treatment response and closest margins and confirm defining fusions or amplifications when indicated.
Interpretation and limitations
Expert review prevents benign mimics and obsolete labels; a positive or close margin is interpreted by its exact anatomical surface and potential for planned re-excision.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Lipoma and atypical lipomatous tumour

A superficial soft mobile fatty lump is often benign, but deep, very large, thick-septated or nodular fat requires MRI and specialist interpretation.

Haematoma or muscle tear

Trauma-related blood should evolve and resolve; internal vascularity, nodular enhancement or enlargement despite time argues for viable tumour and planned biopsy.

Abscess or inflammatory mass

Fever, erythema and fluid can indicate infection, but necrotic sarcoma can mimic an abscess and should not be drained blindly when imaging is atypical.

Peripheral nerve-sheath tumour

Pain or paraesthesia along a nerve and target-like imaging can reflect schwannoma or neurofibroma, while rapid growth, deficit and NF1 raise malignant transformation concern.

Metastasis, lymphoma or desmoid tumour

Epithelial cancer, haematological disease and locally aggressive fibromatosis can present as soft-tissue masses and require adequate core tissue because management differs fundamentally.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Enlarging lumpEscalate uncertain imaging without excisionFirst stepEscalationA soft-tissue mass is enlarging, deep, painful, recurrent or otherwise clinically concerning.

1Document size, depth, mobility, skin and neurovascular findings and arrange urgent ultrasound when this is the appropriate first community test.
2Refer any suspicious or indeterminate lesion to the regional sarcoma diagnostic service for contrast MRI before biopsy and avoid aspiration, steroid injection or shell-out excision.
3Complete MDT-planned core biopsy, expert pathology and CT chest staging, then communicate a definite diagnosis and treatment sequence to the patient and referring team.

02Localised limb or trunk sarcomaAchieve a planned margin and useful functionBiopsy confirms a resectable soft-tissue sarcoma without distant disease.

1Review subtype, grade, size, depth, MRI relationship, patient function and reconstructive needs and decide whether radiotherapy is best before or after operation.
2Remove tumour, reactive zone and biopsy tract intact with a planned negative margin, using nerve, vessel, bone or flap reconstruction when this preserves an oncologically sound limb.
3Review the oriented specimen and margins in MDT, add postoperative treatment when indicated and start wound, lymphatic, mobility and strength rehabilitation early.

03Unplanned excisionRestage the contaminated field before re-excisionA possible sarcoma has been removed without preoperative imaging, adequate margins or sarcoma-team planning.

1Obtain the original slides, blocks, operation note and imaging and arrange expert pathology review without assuming the reported benign or complete status is reliable.
2Perform MRI of the entire surgical bed and CT chest, mapping scar, drain and contaminated planes and considering image-guided biopsy of residual abnormality.
3Use wide tumour-bed re-excision with scar and tract removal, plus risk-adapted radiotherapy and reconstruction, rather than a narrow second attempt around the visible scar.

04Advanced or metastatic diseaseDefine whether the aim is shrinkage, control or symptom reliefSarcoma is unresectable, recurrent or metastatic after histological confirmation.

1Reconfirm subtype and grade, assess pace, symptoms, organ function and molecular targets and discuss lung metastasectomy or focused local treatment for selected limited disease.
2First lineUse doxorubicin first line for many adults, add ifosfamide when a higher response probability justifies toxicity, and select later targeted or histology-specific treatment through the sarcoma MDT.
3Image at predefined intervals, stop ineffective toxic treatment and integrate analgesia, rehabilitation, breathlessness, psychological and specialist palliative support from the outset.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Provides the standard systemic backbone for many unresectable or metastatic adult soft-tissue sarcomas and selected high-risk perioperative pathways.

Doxorubicin

A common first-line adult regimen gives doxorubicin 75 mg/m² intravenously on day 1 every 21 days for up to six cycles, with dose and schedule adjusted to protocol, organ function, response and cumulative exposure.

Use vesicant precautions and baseline cardiac assessment; monitor febrile neutropenia, mucositis, liver function and cumulative cardiomyopathy and check previous anthracycline and chest-radiation exposure.

May be combined with doxorubicin when tumour shrinkage is especially important or used in selected sensitive subtypes and later-line treatment.

Ifosfamide with mesna

Use a specialist fractionated multi-day ifosfamide regimen with equidose mesna uroprotection, intravenous hydration and protocol blood and urine monitoring; exact dose varies by histology and combination.

Monitor haemorrhagic cystitis, encephalopathy, proximal renal tubular injury, myelosuppression, infection and infertility; stop infusion and assess promptly for confusion or somnolence.

Targets angiogenic kinases to delay progression in the licensed and funded later-line population rather than replacing curative local treatment.

Pazopanib

Give pazopanib 800 mg orally once daily on an empty stomach for eligible adults with advanced non-adipocytic soft-tissue sarcoma after prior chemotherapy, reducing or interrupting according to toxicity.

Monitor blood pressure, liver tests, urine protein, thyroid function, ECG risk, bleeding, thrombosis, cardiac failure and wound healing; review acid suppression and CYP3A interactions.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Local neurovascular destruction

Progressive tumour can compress or invade nerves, vessels, muscle, bone and skin, causing pain, weakness, ulceration, bleeding and loss of a salvageable limb.

Pulmonary metastases

High-grade sarcoma commonly relapses in lung; limited deposits can remain amenable to metastasectomy or focused ablative treatment after systemic review.

Unplanned excision contamination

A shell-out operation leaves residual tumour and contaminates scar, drain and tissue planes, requiring wider re-excision and sometimes sacrificing reconstruction options.

Treatment-related morbidity

Wide resection and radiotherapy can cause wound breakdown, fibrosis, lymphoedema, fracture, stiffness and neuropathy, while chemotherapy adds marrow, cardiac, renal and fertility toxicity.

Recurrent retroperitoneal compression

Local recurrence can obstruct bowel, kidney and major vessels, cause cachexia and require repeated complex operations or symptom-focused interventions.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

After surgery, inspect the wound and flap, assess infection, seroma, lymphoedema, distal neurovascular function and range, strength and gait with early rehabilitation.
Use risk-adapted clinical local examination and chest imaging, with MRI of the primary site when deep anatomy cannot be assessed reliably or symptoms arise.
Investigate a new mass, pain, cough or breathlessness between visits immediately rather than reassuring from a recently normal surveillance scan.
During radiotherapy, monitor skin, oedema, wound integrity and function; later assess fibrosis, joint stiffness, neuropathy, fracture and secondary-cancer risk.
During systemic treatment, review blood counts, infection, organ function, symptoms and imaging response at protocol intervals, with an explicit stopping rule for progression or disproportionate harm.
After anthracycline exposure, record cumulative dose and provide symptom- and risk-based cardiac surveillance rather than losing treatment details at discharge.
Track return to work, mobility, pain, sexual and psychological health and access to prosthetic, lymphoedema and palliative services alongside cancer endpoints.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Painless does not mean harmless

Most early soft-tissue sarcomas do not hurt; progressive enlargement is more discriminating than tenderness and should trigger the pathway.

Five centimetres is a referral aid

It is not a biological threshold: a smaller enlarging, deep or atypical lesion can be malignant and still deserves specialist imaging.

The scar maps contamination

After unplanned excision, the operative bed, drain and biopsy route may all contain cells and must be encompassed in re-excision planning.

Preoperative radiation changes the trade-off

Smaller fields and lower late fibrosis are balanced against more early wound complications, so site and reconstruction determine timing.

Response need can justify combination therapy

Doxorubicin-ifosfamide is more toxic and not routine for everyone, but greater shrinkage may matter when relieving compression or enabling local control.

Histology directs later lines

A single sarcoma ladder is unsafe because liposarcoma, leiomyosarcoma, angiosarcoma and fusion-driven tumours differ in drug and local-treatment sensitivity.

11Common pitfallsFrequent interpretation and management errors.

01
Calling a painless growing mass a lipoma without imaging.
02
Using repeated antibiotics, aspiration or steroid injection for an unexplained enlarging lump.
03
Accepting a haematoma diagnosis when there is no adequate trauma or expected resolution.
04
Performing MRI only after excision has distorted the tumour compartment.
05
Placing a transverse core or open-biopsy tract that cannot be removed with the specimen.
06
Relying on fine-needle aspiration alone for subtype and grade.
07
Assuming a small superficial mass cannot be sarcoma.
08
Treating all subtypes with the same chemotherapy sequence.
09
Ignoring the chest because the local tumour appears resectable.
10
Following scans without restoring limb, lymphatic, work and psychological function.