Synonyms

Lipomatous sarcoma

Category

Soft tissue

Behaviour

Malignant

Grade

Variable

Gender

M = F

Tissue of Origin

Adipose

Epidemiology

• Most common soft tissue sarcoma in adults
• Peak incidence 40-60 years
• Arises from deep soft tissues, rarely subcutaneous
• Four main subtypes: well-differentiated, myxoid, round cell, pleomorphic

Clinical Features

• Painless mass, often large at presentation
• Rapid growth particularly in myxoid subtype
• Located in deep tHigh, retroperitoneum, chest wall

Location

• Deep tHigh (most common)
• Retroperitoneum
• Chest wall
• Deep Lower extremities

Imaging

• MRI shows fatty lesion with areas of enhancement
• Heterogeneous signal on T2-weighted imaging
• Well-differentiated: predominantly fatty appearance
• Myxoid/round cell: more cellular, increased enhancement

Pathology

• Mature adipocytes with lipoblasts
• Fibrous septa separating fat lobules
• Myxoid stroma in myxoid subtype
• Round cells with increased mitotic activity

Genetics

• t(12;16)(q13;p11) - CHOP gene fusion in myxoid subtype
• Supernumerary ring chromosomes in well-differentiated

Treatment

• Wide surgical excision with negative margins
• Chemotherapy for High-grade and myxoid subtypes
• Radiotherapy for High-grade or unresectable tumours

Prognosis

• Well-differentiated: excellent prognosis with surgery alone
• Myxoid: intermediate prognosis, 5-year survival 60%
• Pleomorphic: poor prognosis, aggressive behaviour

Key Points

• Most common STS in adults
• Subtype determines behaviour and prognosis
• Wide excision is mainstay of treatment
• Follow-up imaging critical for detection of recurrence

Workup - Local Imaging

MRI for local staging

Workup - Biopsy

• Core needle biopsy for diagnosis
• Assess subtype and grade

Workup - Staging

CT CAP

Follow-up Summary

• Years 1–2: 3–4 monthly clinical review + CXR; MRI primary site at 3 months post-op then 6-monthly
• CT chest every 3–4 months for first 2 years (pulmonary metastasis is primary concern)
• Years 3–5: 6-monthly clinical review + CXR; CT chest 6-monthly
• Years 6–10: Annual clinical review + CXR; CT chest annually
• Discharge at 10 years with documented self-monitoring advice
• Radiotherapy patients: monitor irradiated field for late effects at each review