Synopsis
Recognise a potentially malignant soft-tissue mass before unplanned removal, use specialist ultrasound, MRI and tract-planned core biopsy to establish subtype and grade, then coordinate wide surgery, radiotherapy, systemic treatment, rehabilitation and recurrence surveillance.
- 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.
Key red flags
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.
Rapidly increasing pain, weakness, numbness, coolness, absent pulse or tense swelling indicates urgent compartment and vascular assessment.
Investigation priorities
Determine whether an enlarging superficial lump is cystic, fatty, solid, vascular or deep and identify features requiring referral.
Define local tumour extent, fascial compartment, necrosis, oedema and relationship to skin, bone, joints, nerves and vessels before biopsy.
Management branches
A soft-tissue mass is enlarging, deep, painful, recurrent or otherwise clinically concerning.
- Document size, depth, mobility, skin and neurovascular findings and arrange urgent ultrasound when this is the appropriate first community test.
- Refer 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.
- Complete MDT-planned core biopsy, expert pathology and CT chest staging, then communicate a definite diagnosis and treatment sequence to the patient and referring team.