Histopathological Grading of Soft Tissue Tumour
Malignant soft tissue tumours constitute
a heterogeneous group of tumours with a wide range of biological behaviour.
Histopathological grading is essential for separating tumours with favourable prognosis to those with poor prognosis and determines overall survival of the patient.
Pathologists are required to indicate biological potential of the tumour, so that appropriate treatment regimen may be selected by the clinician.
The criteria used in the grading scheme do not equally apply for all tumour types.
Treating clinician should be aware of the limitations of the grading scheme, as there are frequent failures in the prediction of clinical outcome.
Note: Needle biopsies are not ideal for preoperative grading purposes.
Parameters used in grading:
Accurate histological typing of the tumour
plays an important role in determining tumour prognosis in the
Extraskeletal Ewing's sarcoma/PNET
Myxoid / round cell liposarcoma
Low Grade Tumours:
Angiomatoid fibrous histiocytoma
Atypical lipomatous tumour/well differentiated
National Cancer Institute Grading System:
Grading in this system is based on histological type of tumour and tumour necrosis where histological type does not define grade.
Histological Parameters Grade
Histological Type / Subtype 1
- Epithelioid haemangioendothelioma
- Well differentiated liposarcoma
- Myxoid liposarcoma
- Infantile fibrosarcoma
Histological type, mitosis, differentiation 1
- Well-differentiated leiomyosarcoma
(< 6 mitosis /10HPF)
- Well- differentiated fibrosarcoma
(< 6 mitosis / 10HPF)
- Malignant peripheral nerve sheath tumour (< 6 mitosis/ 10HPF)
- Extraskeletal myxoid chondrosarcoma (no mitoses)
Histological type, Necrosis 2
- Any sarcoma not compulsorily grade 3 and less than 15% necrosis.
Histological Type / Subtype 3
- Any sarcoma with more than 15% necrosis
- Rhabdomyosarcoma (all subtypes)
- Extraskeletal osteosarcoma
- Ewing's sarcoma /primitive neuroectodermal tumour
- Mesenchymal chondrosarcoma
- Pleomorphic liposarcoma
- Alveolar soft part sarcoma
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