Synonyms

• LMS
• Smooth muscle sarcoma

Category

Soft tissue

Behaviour

Malignant

Grade

Variable

Gender

M = F

Tissue of Origin

Smooth muscle

Epidemiology

• Second most common STS in adults
• Peak incidence 50-70 years
• Can arise in any location with smooth muscle
• Often deep-seated and large at diagnosis

Clinical Features

• Painless or mildly painful mass
• Rapid growth in some cases
• May present with complications (GI bleeding if visceral)

Location

• Retroperitoneum
• Deep tHigh
• GI tract
• Biliary tract
• Subcutaneous tissues (rare)

Imaging

• MRI shows heterogeneous T2 signal
• Varying enhancement post-contrast
• May show necrosis or hemorrhage
• Difficult to distinguish from Benign leiomyoma

Pathology

• Fascicular arrangement of smooth muscle cells
• Increased mitotic activity
• Spindle cell morphology
• Cytologic atypia

Genetics

• No specific recurrent cytogenetic abnormality
• Complex karyotypes common

Treatment

• Wide surgical excision primary treatment
• Adjuvant chemotherapy for High-grade/large tumours
• Radiotherapy for unresectable or recurrent disease

Prognosis

• Grade and size most important prognostic factors
• 5-year survival 50% for High-grade
• Retroperitoneal location associated with worse prognosis

Key Points

• Second most common STS
• Often presents at advanced stage
• Grade and depth crucial for treatment planning
• Regular imaging Follow-up essential

Workup - Local Imaging

MRI with contrast

Workup - Biopsy

• Core needle biopsy recommended
• Assess grade and mitotic activity

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