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Soft Tissue Tumors

Introduction

Grading


Reviewer: Komal Arora, M.D. (see Reviewers page)
Revised: 19 July 2012, last major update July 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Indicate in pathology report which grading system is used
● Grade is most important prognostic factor and indicator of metastatic risk in adults (Arch Pathol Lab Med 2006;130:1448)

Two grade systems - low grade and high grade:
Low grade: usually has limited ability to metastasize
High grade: cellular with mitotic figures and necrosis, but must evaluate in context of tumor type, age and location
● For example: superficial high grade MFH is unlikely to metastasize, but deep low grade MPNST is likely to metastasize
● Necrosis usually signifies high grade unless tumor is well differentiated and lacks pleomorphism


Grading systems - French Federation of Cancer Centers Sarcoma Group

General
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Grade 1: total score of 2-3 points
Grade 2: total score of 4-5 points
Grade 3: total score of 6-8 points

Tumor differentiation:
1 point: resembles normal adult mesenchymal tissue, may be confused with a benign lesion, such as well differentiated liposarcoma
2 points: histologic typing is certain, such as myxoid liposarcoma
3 points: synovial sarcoma, osteosarcoma, Ewing’s sarcoma/PNET, sarcomas of doubtful tumor type, embryonal and undifferentiated sarcomas

Mitotic count (count 10 successive high power fields [area of 0.17 mm squared] in most mitotically active areas):
1 point: 0-9 mitoses
2 points: 10-19 mitoses
3 points: 20 or more mitoses

Tumor necrosis:
0 points: no necrosis on any slides
1 point: less than 50% necrosis for all examined tumor surface
2 points: tumor necrosis of 50% or more of examined tumor surface


Grading systems - French Federation of Cancer Centers Sarcoma Group - grades of common sarcoma types

General
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● Angiosarcoma-poorly differentiated/epithelioid - 3
● Angiosarcoma-well differentiated/conventional - 2
● Chondrosarcoma-mesenchymal - 3
● Clear cell sarcoma - 3
● Epithelioid sarcoma - 3
● Fibrosarcoma-conventional - 2
● Fibrosarcoma-well differentiated - 1
● Fibrosarcoma-poorly differentiated - 3
● Leiomyosarcoma-conventional - 2
● Leiomyosarcoma-epithelioid / poorly differentiated / pleomorphic - 3
● Leiomyosarcoma-well differentiated - 1
● Liposarcoma-myxoid - 2
● Liposarcoma-pleomorphic - 3
● Liposarcoma-round cell - 3
● Liposarcoma-well differentiated - 1
● Malignant triton tumor - 3
● MFH-giant cell - 3
● MFH-pleomorphic with storiform pattern - 2
● MFH-pleomorphic without storiform pattern - 3
● Myxofibrosarcoma - 2
● Osteosarcoma - 3
● PNET - 3
● Rhabdomyosarcoma-alveolar / embryonal / pleomorphic - 3
● Synovial sarcoma – 3

Additional references
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Pathol Int 2007;57:121


Grading systems of soft tissue tumors - National Cancer Institute (US) tumor grading system

General
=========================================================================

Grade 1:
● Well differentiated liposarcoma
● Myxoid liposarcoma (grade 2 in French system above)
● Subcutaneous myxoid MFH
● Well differentiated malignant hemangiopericytoma with < 1 MF/10 HPF, no necrosis and no hemorrhagic areas
● Well differentiated fibrosarcoma with orderly herringbone pattern or well differentiated leiomyosarcoma with orderly fascicular pattern plus well differentiated cytologic features, no pleomorphism, no necrosis, < 6 MF/10 HPF
● Malignant schwannoma (MPNST) if resembles neurofibroma plus mitotic figures plus areas of high cellularity but < 6 MF/10 HPF
● Myxoid chondrosarcoma that is uniformly myxoid and hypocellular with no mitotic activity

Grade 2:
● Other histologic types with <15% necrosis

Grade 3:
● Extraskeletal Ewing’s sarcoma, PNET, extraskeletal osteosarcoma, mesenchymal chondrosarcoma, malignant triton tumor, or other histologic types with 15% or more necrosis

Additional references
=========================================================================

J Clin Oncol 1997;15:350, J Surg Oncol 1989;41:263

End of Soft Tissue Tumors > Introduction > Grading


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