III - SOFT TISSUE TUMORS OTHER THAN RHABDOMYOSARCOMA

GENERAL CONSIDERATIONS

Malignant soft tissue tumours are unusual in adolescents and children. We will only address to those which are more specific or characteristic of this age group.

Children with sarcomas, (especially under 2 years) have 7% to 33% of genetic predisposition to cancer in general

Fine needle biopsy (FNA) of soft tissue lesions is one of the greatest challenges of cytology:

  • General pathologists are not familiar with this kind of lesions
  • These lesions are generally morphologically heterogeneous
  • Smears are usually paucicellular which precludes ancillary techniques
  • Differentiation is seldom recognizable
  • The recognition of malignancy or borderline lesions is difficult, or even impossible
  • Grading of sarcomas is in most of the cases impossible and the main aim is to distinguish high and low grade-It should be based on:
    • Cellularity: 1point for low; 3 for high
    • Nuclear atypia: 1point for low; 3 for high
    • Mitosis/200 cells- 1point if 0-2; 3 points if >5
    • Necrosis: 1 point for absent; 3 if present
    • Grade 1 if score 4-6, Grade 3 if score 10-12

 

It is advisable:

  • Multidisciplinary approach
  • Extensive sampling of the tumour, which should include:
    • Material for cell block
    • Collection of fresh material for further ancillary studies (e.g., cytogenetic, flow cytometry, electron microscopy, etc...)

 

A number of features should be always evaluated:

  • Cellularity
  • Background and kind of matrix
  • Cell morphology
  • Degree of differentiation
  • Mitotic activity
  • Vascular pattern
  • Necrosis      
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