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Sarcoma

Section: Surgical Oncology Curriculum: Curriculum, page 65

Definition

  • Sarcomas are a rare and heterogenous group of malignant tumours of mesenchymal origi

Incidence

  • Comprise 1% of malignancies in adults and 10% in children.

Risk Factors

Subtypes

Most common subtypes

  • Adults
    • Liposarcoma
    • Leiomyosarcoma
    • Undifferentiated pleomorphic sarcoma
  • Children
    • Rhabdomyosarcoma
    • Ewing sarcoma

Liposarcoma

  • Arise from precursors of adipocytes
  • 20% of all soft tissue sarcomas
  • Most common tumours in adults, rare in children.
  • Commonly found in extremities and retroperitoneum.
  • Five main subtypes
    • Well-differentiated (low grade)
      • If arising in extremity - atypical lipomatous tumours.
        • Do not metastasise to other organs
      • If arising in retroperitoneum - called well differentiated lipomatous tumours.
        • Have a very low risk of malignancy or spread to other sites
        • But have a propensity for local recurrence in the retroperioneum and can recur as dedifferentiated subtype
      • Have an amplification of MDM2/CDK4 gene which can tested for with FISH
      • Should be tested for as it will identify is lesion is low grade lipomatous tumour/well differentiated tumour/liposarcomas from benign lesions.
    • Myxoid (intermediate grade)
      • metastasis to other soft tissue sites and bone marrow.
    • Round cell (high grade)
    • Pleomorphic (high grade)
      • metastasis to the lung.
    • Dedifferentiated (high grade)

Leiomyosarcoma

  • Arise from smooth muscle of the GI tract, uterus, IVC.
  • Usually retroperitoneal or visceral.

Undifferentiated pleomorphic sarcoma

  • This term is reserved for sarcomas that lack specific lines of differentiation
    • “Unclassified soft tissue sarcoma”
    • Used to be called malignant fibrous histiocytoma
    • Some pathologists use the term “sarcoma, not otherwise specified”.
  • Are high grade lesions
  • Generally arise from extremities or retroperitoneum.
  • Often large at diagnosis - 5-10cm
  • Subsets describe the predominant cell seen on microscopic examination
    • Round cell
    • Spindle cell

Angiosarcoma

  • Arise from endothelial cells
  • Include
    • Scalp in older adults
    • Breast or chest wall after therapeutic radiation for breast ϲanϲеr
    • An extremity in conjunction with chronic lymphedema Stewart-Treves Syndrome
    • Deep soft tissues
    • Liver or spleen
    • Heart or large vessels.
  • Usually high grade and not responsive to treatment.
  • Is commonly caused by therapeutic radiation - especially for breast cancer or Hodgkin lymphoma

Solitary fibrous tumour

  • Slow growing tumour which arises from the pleura, pelvis or dura.
  • Can reach a very large size before they are detected.
  • Often have a very low risk of metastasis
  • 5% of patients present with hypoglycaemia related to overexpression of insulin like growth factor 2 (IGF-2)

Rhabdomyosarcoma

  • Tumours which come from skeletal muscle.
  • Most common soft tissue sarcoma of childhood.
  • Most common location is the head or neck region
    • Can also occur in retroperitoneum, GU tract, limbs.
  • 4 main subtypes
    • Embryonal
    • Alveolar
    • Pleomorphic
    • Spindle cell

Ewing sarcoma

  • Small round blue cell tumor
  • Most commonly arises in the long bones (femur, tibia, humerus) but can also occur in the pelvis, ribs, and spine
  • Affects children

Others

Clinical

  • History
    • How lump was identified? How long has it been there for? How quick has it grown?
    • Associated symptoms - associated with neurological symptoms like paresthesia - can occur due to invasion of the nerves.
    • Any trauma or radiotherapy to the area?
    • Any other symptoms - swelling, redness, heat.
    • Any lesions elsewhere on the body?
    • Fevers? Chills? Night sweats? Weight loss?
  • Examination
    • Size, location, relationship to other structures.
    • Comment on overlying skin - any involvement/ulceration.
    • Palpation
      • Hard, soft, smooth
      • Mobility
      • Depth
    • Look for previous scars or biopsy sites - will need to be incorporated into any surgery
    • Examine regional lymph nodes
      • Some sarcomas (including rhabdomyosarcoma) can spread to lymph nodes
    • Neurovascular examination
    • Look for evidence of systemic disease - listen to chest and feel liver edge.
    • Look for stigmata of neurofibromatosis - Café-au-lait spots and axillary freckling.
  • Symptoms
    • Usually present as slowing enlarging, painless mass.
    • Can develop pain or paresthesia from compression
  • When to consider a lump may be a soft tissue sarcoma?
    • Clinical
      • Greater than 5cm in size or a golf ball
      • Rapid growth phase
      • Painful
    • Radiological
      • Deep to the deep fascia.
      • Non-fatty component/solid section.
      • Vascularity on the USS.
      • Heterogeneity within the lipoma.
      • Thick septa
      • Evidence of infiltration in to adjacent structures.
  • Pattern of growth
    • Grow along tissue planes and only rarely traverse of violate major fascial planes or bone.
    • Growing tumour compresses surrounding normal tissue - develops a pseudocapsule which is comprised of normal tissue with poorly defined margins and fingerlike tumour projections which infiltrate adjacent tissues.
  • Pattern of spread
    • Haematogenous - mostly to lung
    • Lymph node metastasis is very rare - can occur with Rhabdomyosarcoma and angiosarcomas.

Location

  • Extremity
    • Liposarcoma & malignant fibrous histiocytoma (MFH)
  • Retroperitoneal
    • Liposarcoma & leiomyosarcoma
  • Visceral
    • GIST, Leiomyosarcoma, Desmoid
  • Children
    • Rhabdomyosarcoma
  • Young adults
    • Synovial sarcoma

Differential Diagnosis

  • Benign soft tissue lesions (100 x more common)
    • Lipoma
  • Malignant tumours
    • Metastatic carcinoma
    • Melanoma
    • Lymphoma

Investigations

Imaging

  • MRI
    • For lesions of the extremities, trunk, head and neck.
  • CT
    • For abdominal, visceral, and retroperitoneal lesions
  • Staging
    • All patients need to have completion CT chest
  • PET/CT
    • Is not recommended for the diagnosis of sarcoma but is used for detecting recurrence.

Biopsy

  • Discuss at MDM first
  • Core-needle biopsy - the site needs to be carefully considered as the tract will need excision
    • Biopsy site is ideally chosen by the surgeon planning the definitive resection
    • Consideration of tattooing biopsy tract
    • ^this is all classic teaching but not really followed anymore - for exmaple for a retroperitoneal lesion biopsy is performed through the back often and this track is not excised and the risk of seeding is very low
      • But still should discuss at MDM first prior to biopsy
  • Other option is incisional biopsy

Histopathology

  • WHO classifies soft tissue neoplasms according to their presumptive tissue of origin i.e. angiosarcoma, liposarcoma etc.
    • Where histogenesis is uncertain - they are named based on their architectural pattern i.e. clear cell sarcoma, alveolar sarcoma.
  • IHC stains can aid is determining subtype
    • Desmin - stains positive for RMS and leiomyosarcomas.
    • S100 antigen - tumours from the neural sheath.
    • Cytokeratin - synovial sarcomas.
    • Factor VIII related antigen - endothelial origin.

Grade

  • Sarcomas are grade using the French Federation of Сanϲеr Centers Ѕаrсoma Group (FNCLCC) system which is based on three factors
    • Differentiation
      • 1 - sarcoma looks like normal tissue,
      • 2 - histological subtype is certain,
      • 3 - Embryonal and undifferentiated sarcoma or specific high grade types).
    • Mitotic count
      • 1 - 0-9 mitoses for 10HPF
      • 2 - 10-19 mitosis per 10HPF
      • 3 - >20 mitosis per 10HPF
    • Tumour necrosis
      • 0 - no necrosis
      • 1 - <50% necrosis
      • 2 >50% necrosis
  • Grade
    • Grade 1 - score of 2 or 3
    • Grade 2 - score of 4 or 5
    • Grade 3 - score of 6, 7, or 8

Stage

8th edition AJCC

  • Separates extremity/trunk and retroperitoneum

Extremity/trunk

T categoryT criteria
TXPrimary tumor cannot be assessed
T0No evidence of primary tumor
T1Tumor 5 cm or less in greatest dimension
T2Tumor more than 5 cm and less than or equal to 10 cm in greatest dimension
T3Tumor more than 10 cm and less than or equal to 15 cm in greatest dimension
T4Tumor more than 15 cm in greatest dimension
N categoryN criteria
N0No regional lymph node metastasis or unknown lymph node status
N1Regional lymph node metastasis
M categoryM criteria
M0No distant metastasis
M1Distant metastasis
When T is…And N is…And M is…And grade is…Then the stage group is…
T1N0M0G1, GXIA
T2, T3, T4N0M0G1, GXIB
T1N0M0G2, G3II
T2N0M0G2, G3IIIA
T3, T4N0M0G2, G3IIIB
Any TN1M0Any GIV
Any TAny NM1Any GIV

Retroperitoneum

  • TNM is the same catogries are the same
  • Stage is almost the same with one exception
    • Any T, N1, M0, Any G is IIIB (not stage IV)
Any TN1M0Any GIIIB
Any TAny NM1Any GIV

Nomogram for Survival

  • The AJCC specifically recommends the use of a prognostic nomogram to estimate the likelihood of postoperative survival as the ability to discriminate outcome based on tumor size alone is limited

Prognostic factors

  • Main factors
    • Grade
    • Tumor size
    • Pathologic stage
  • Postoperative nomograms
    • The “Sarculator” prognostic tool is available online and incorporates externally validated nomograms for overall survival and risk of distant metastases after resection of a primary extremity soft tissue ѕаrcοmа
    • Memorial Sloan Kettering Сaոϲеr Center (MSKCC) nomogram – The MSKCC postoperative nomogram for 12-year ѕаrсοmа-specific death applies to all anatomic sites
    • The Helsinki University ѕаrcomа nomogram – This is an externally validated, web-based, prognostic tool for extremity and abdominal wall sarcomas to predict 10 year ѕаrcomа specific survival

Treatment

Graph View

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