What are the clinical presentation and diagnosis of sarcoma?

Clinical Presentation and Diagnosis of Sarcoma

The most common presentation of a sarcoma is a painless enlarging soft tissue mass, with clinical recognition being particularly challenging for deep-seated tumors, resulting in a median size at diagnosis of over 9 cm. 1

Clinical Presentation

Key Presenting Features

• Painless enlarging soft tissue mass (most common presentation) 1
• Progressive non-mechanical bone pain (particularly at night) for bone sarcomas 1
• Swelling and functional impairment (later signs when tumor progresses through cortex) 1
• Constitutional symptoms are rare 2

High-Risk Features

• Soft tissue mass increasing in size
• Size >5 cm
• Deep-seated location
• Pain (though many soft tissue sarcomas are painless) 1, 2

Anatomical Considerations

• Soft tissue sarcomas can occur at any anatomical site
• Common locations include extremities, pelvis, trunk, abdomen, retroperitoneum, and head/neck 3
• Retroperitoneal and deep-seated tumors (e.g., thigh) are particularly challenging to recognize clinically 1
• Atypical lipomatous tumors tend to be larger, deep-seated, and in the lower limb 1

Diagnostic Approach

Initial Evaluation

1. Imaging:

   • For soft tissue masses:

     • MRI is the main imaging modality for extremities, pelvis, and trunk 1
     • Ultrasound as first-line screening tool for unexplained lumps 1

   • For bone lesions:

     • Conventional radiography in two planes as first investigation 1
     • MRI of whole bone with adjacent joints if malignancy cannot be excluded 1

2. Referral Criteria:

   • Urgent direct access ultrasound (within 2 weeks) for adults with unexplained lump that is increasing in size 1
   • Suspected cancer pathway referral (within 2 weeks) if ultrasound findings suggest sarcoma or if clinical concern persists despite uncertain findings 1
   • All patients with bone lesions suspected to be primary bone sarcomas should be referred to specialized centers 1

Definitive Diagnosis

1. Biopsy:

   • Multiple core needle biopsies (using 14-16G needles) is standard approach 1
   • Excisional biopsy may be appropriate for superficial lesions <3-5 cm 1
   • Biopsy should be performed by the surgeon who will perform definitive resection or by a dedicated interventional radiologist after discussion with surgeon 1
   • Biopsy pathway and scar should be planned to be safely removed during definitive surgery 1

2. Pathological Assessment:

   • Histological diagnosis according to WHO classification 1
   • Expert pathological second opinion recommended in all cases 1
   • Frozen-section technique for immediate diagnosis is not encouraged 1
   • Molecular analysis may be necessary for certain subtypes 1

Staging

• General staging to assess extent of distant disease:
  • Chest CT
  • Bone scintigraphy
  • Whole-body MRI and/or FDG-PET-CT/MRI as clinically indicated 1

Special Considerations

Multidisciplinary Approach

• Management should be carried out in reference centers for sarcomas with multidisciplinary expertise 1
• Team should include pathologists, radiologists, surgeons, radiation therapists, medical oncologists, and organ-based specialists as applicable 1

Common Pitfalls

• Misdiagnosis occurs in approximately 30% of cases, leading to delays in appropriate therapy 4
• Recent injury does not rule out malignant tumor and should not prevent appropriate diagnostic procedures 1
• Benign lesions (lipomas, cysts) are much more common and can be confused with sarcomas 1
• Sarcomas can be misdiagnosed as other conditions such as osteomyelitis or metastatic disease 1

Age-Related Considerations

• In patients <5 years: destructive bone lesions more likely to be metastatic neuroblastoma or Langerhans cell histiocytosis 1
• In patients >40 years: bone metastases and myeloma are more common than primary bone sarcomas 1

Risk Factors and Etiology

• Most soft tissue sarcomas have unknown etiology 1
• Genetic predisposition:
  • Neurofibromatosis (NF1 gene mutations) - 10% lifetime risk of MPNST 1
  • Familial retinoblastoma (RB gene mutations) 1
  • Li-Fraumeni syndrome (TP53 mutations) 1
• Environmental factors:
  • Therapeutic irradiation (most important) 1
  • Chronic lymphedema (associated with cutaneous angiosarcoma) 1
  • UV radiation (associated with cutaneous angiosarcomas and atypical fibroxanthoma) 1