Soft Tissue Sarcomas

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Introduction & Etiology - The Sneaky Lumps

  • Rare, malignant mesenchymal tumors originating from connective tissues (e.g., fat, muscle, nerve, blood vessels, deep skin tissues).
  • Peak incidence: 40-60 years; slight male predilection.
  • Etiology largely unknown for most; risk factors include:
    • Genetic syndromes: Neurofibromatosis type 1 (NF1), Li-Fraumeni (p53 mutation), Gardner syndrome.
    • Prior radiation therapy (latency period 5-15 years).
    • Chronic lymphedema (e.g., Stewart-Treves syndrome).
    • Chemical exposure (e.g., vinyl chloride, arsenic).
    • Trauma: role remains controversial. Soft tissue sarcoma clinical presentation and imaging

⭐ Most soft tissue sarcomas arise de novo, not from pre-existing benign lesions.

Clinical Features & Diagnosis - Clues & Confirmation

  • Clues: Most commonly a painless, progressively enlarging mass. Suspect malignancy if:
    • Size >5 cm (often compared to a golf ball)
    • Deep to fascia (not superficial)
    • Rapid growth or newly painful
    • Fixed to underlying structures
  • Confirmation:
    • Imaging:
      • X-ray/USG: Initial; assess calcification, cystic vs solid nature.
      • MRI: Key for local staging (size, depth, neurovascular relation, involved compartments).
      • CT Chest: Screens for lung metastases (most common site).
    • Biopsy: Essential for definitive diagnosis & grading. Image-guided core needle biopsy is standard. Incisional if core non-diagnostic. Crucially, avoid unplanned excisions. MRI of soft tissue sarcoma in leg

⭐ MRI is the imaging modality of choice for local staging of soft tissue sarcomas.

Staging & Grading - Sizing Up the Foe

  • Staging (AJCC 8th Ed.):
    • T (Tumor): Size & depth. T1: ≤5cm; T2: >5-10cm; T3: >10-15cm; T4: >15cm. 'a' superficial, 'b' deep.
    • N (Nodes): N0 (no nodes), N1 (regional nodes).
    • M (Metastasis): M0 (no distant mets), M1 (distant mets).
  • Grading (FNCLCC): Crucial for prognosis.
    • Score: Sum of Differentiation, Mitotic count, Necrosis.
    • Grades: G1 (Score 2-3), G2 (Score 4-5), G3 (Score 6-8).

⭐ Tumor grade (especially FNCLCC) is one of the most important prognostic factors in localized soft tissue sarcoma.

Common STS Types - Know Your Villains

  • Liposarcoma: Most common adult STS. Well-differentiated (MDM2 amp), Myxoid (t(12;16) FUS-DDIT3), Pleomorphic.
  • Leiomyosarcoma: Smooth muscle. Uterus, retroperitoneum. Spindle cells, cigar-shaped nuclei.
  • Rhabdomyosarcoma: Commonest childhood STS. Skeletal muscle origin. Embryonal (botryoid), Alveolar (t(2;13) PAX3-FOXO1).
  • Synovial Sarcoma: Young adults, near joints (knee). Biphasic/monophasic.

    ⭐ Synovial sarcoma is characterized by the t(X;18) (SYT-SSX) translocation.

  • MPNST: Malignant Peripheral Nerve Sheath Tumor. From peripheral nerves/neurofibromas. Strong NF1 association. S100 variable.
  • UPS: Undifferentiated Pleomorphic Sarcoma (formerly MFH). Exclusion diagnosis. Storiform pattern.
  • Angiosarcoma: Endothelial. Skin, breast (post-radiation). CD31, CD34 positive.

Management Principles - Battling the Bulk

  • Multidisciplinary Team (MDT) approach is crucial.
  • Staging (TNM) guides treatment strategy.

⭐ The cornerstone of curative treatment for localized soft tissue sarcoma is wide surgical excision with negative margins.

  • Surgery: Wide local excision (WLE) aiming for R0 (negative) margins. Limb salvage preferred.
  • Radiotherapy (RT):
    • Neoadjuvant: ↓tumor size, ↑resectability.
    • Adjuvant: ↓local recurrence for high-grade/large tumors.
  • Chemotherapy (CTx):
    • Adjuvant/Neoadjuvant: For high-risk, chemosensitive subtypes (e.g., Synovial Sarcoma). Doxorubicin-based.
    • Palliative: For metastatic disease. Soft Tissue Sarcoma Treatment Algorithm

High‑Yield Points - ⚡ Biggest Takeaways

  • MRI is crucial for local staging of soft tissue sarcomas.
  • Core needle biopsy is preferred for diagnosis; longitudinal incision for open biopsy.
  • Wide local excision with negative margins is the treatment cornerstone.
  • Adjuvant radiotherapy for large, high-grade tumors improves local control.
  • Lungs are the most common site of distant metastasis.
  • Adults: Undifferentiated Pleomorphic Sarcoma (UPS), Liposarcoma; Children: Rhabdomyosarcoma.
  • Tumor grade is a critical prognostic factor.

Practice Questions: Soft Tissue Sarcomas

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Flashcards: Soft Tissue Sarcomas

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If the size of the lesion is >2/3, it is given a score of _____ according to Mirel's criteria

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If the size of the lesion is >2/3, it is given a score of _____ according to Mirel's criteria

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