General Surgery · Year 3 · from General Surgery

Case 2: Soft Tissue Sarcoma

Patient Demographics

  • Age: 45 years
  • Sex: Female
  • Occupation: Physical therapist

Chief Complaint

"I noticed a lump in my thigh that has been growing over the past few months."

History of Present Illness

The patient first noticed a mass in her right anterior thigh approximately 4 months ago. Initially, she thought it was a muscle strain from exercise. However, the mass has been gradually enlarging and is now easily palpable. It is deep-seated, firm, and only mildly uncomfortable. She has no history of trauma to the area. She denies fever, weight loss, or other constitutional symptoms.

Past Medical History

  • No significant medical history
  • No prior cancers
  • No radiation exposure

Physical Examination

  • General: Well-appearing female
  • Right thigh:
  • 8 cm firm, deep-seated mass in anterior thigh
  • Fixed to underlying structures
  • Non-tender
  • No overlying skin changes
  • No inguinal lymphadenopathy
  • Neurovascular: Intact distally

Clinical Suspicion

Red flags for soft tissue sarcoma:

  • Size >5 cm
  • Deep location (below fascia)
  • Growing mass
  • Fixed to underlying tissue

Imaging Workup

MRI Right Thigh:

  • 9.2 x 7.5 x 6.8 cm heterogeneous mass
  • Located deep to fascia within quadriceps muscle compartment
  • T1: Intermediate signal
  • T2: Heterogeneous high signal
  • Enhancement: Peripheral and heterogeneous
  • No involvement of femur
  • Relationship to femoral vessels: Close but distinct

Imaging for Staging

CT Chest: No pulmonary metastases (lungs are most common site of sarcoma metastasis)

Tissue Diagnosis

Core needle biopsy (preferred over open biopsy when possible):

  • Approach: Through muscle belly that would be excised with tumor
  • Result: High-grade pleomorphic sarcoma
  • Immunohistochemistry: MDM2 amplification negative, non-specific markers
  • Final diagnosis: Undifferentiated pleomorphic sarcoma (UPS), high-grade

Staging

  • Tumor size: >10 cm → T3
  • Grade: High (Grade 3)
  • Nodes: N0
  • Metastasis: M0
  • Stage III (T3 N0 M0, high-grade)

Multidisciplinary Tumor Board

  • High-grade soft tissue sarcoma of thigh
  • Close to neurovascular structures
  • Options:
  1. Upfront surgery with adjuvant radiation
  2. Neoadjuvant radiation followed by surgery

Decision: Neoadjuvant radiation preferred (larger field but lower dose, fewer wound complications than adjuvant radiation in extremity STS)

Neoadjuvant Radiation Therapy

  • 50 Gy in 25 fractions over 5 weeks
  • MRI post-treatment: Stable size with some internal changes

Surgical Management (4-6 weeks after radiation)

Wide local excision:

  • Limb-sparing surgery
  • En bloc resection of tumor with surrounding cuff of normal tissue
  • Margin goal: 1-2 cm or intact fascial barrier
  • Femoral vessels preserved (no encasement)
  • Femoral nerve preserved
  • Quadriceps muscle partially resected with tumor

Pathology

  • Undifferentiated pleomorphic sarcoma, high-grade
  • Size: 8.5 cm (some treatment effect)
  • Margins: R0 (negative, closest margin 1.2 cm)
  • Treatment response: 40% necrosis

Postoperative Course

  • Wound healing delayed (expected with neoadjuvant radiation)
  • Wound VAC therapy for 2 weeks
  • Secondary closure achieved
  • Physical therapy for quadriceps strengthening

Adjuvant Therapy

  • No adjuvant chemotherapy given (role in STS is limited, controversial for most subtypes)
  • Surveillance imaging recommended

Surveillance Protocol

  • History/physical every 3-6 months for 2-3 years, then annually
  • Chest imaging (CT or X-ray) every 6 months for 2-3 years
  • Local imaging (MRI) if clinically indicated
  • Surveillance for 10 years (late recurrences can occur)

Teaching Points

  1. Mass >5 cm, deep location, growing = consider sarcoma
  2. MRI is imaging modality of choice for extremity soft tissue masses
  3. CT chest for lung staging (most common metastatic site)
  4. Core biopsy preferred; if open biopsy needed, plan incision along potential resection
  5. Limb-sparing surgery + radiation is standard (amputation rarely needed)
  6. Neoadjuvant radiation may improve limb function, adjuvant radiation may have fewer wound issues
  7. Margins and grade are most important prognostic factors

Clinical Image

Image Description: MRI of the thigh demonstrating a large, deep-seated soft tissue sarcoma within the muscle compartment. The heterogeneous signal intensity and enhancement pattern are characteristic of high-grade sarcoma.

Attribution: Image from Wikimedia Commons. Source: https://commons.wikimedia.org/wiki/Category:Skin_cancers

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