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Comments (Soft Tissue)
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Comments (Soft Tissue)
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FNCLCC Grading
The FNCLCC grade is based on 3 parameters: differentiation, mitotic activity, and necrosis. Each of these parameters receives a score: differentiation (1 to 3), mitotic activity (1 to 3), and necrosis (0 to 2). The scores are summed to produce a grade.
Grade 1: 2 or 3
Grade 2: 4 or 5
Grade 3: 6 to 8
Differentiation: Tumor differentiation is scored as follows (see Table 2).
Score 1: Sarcomas closely resembling normal, adult mesenchymal tissue and potentially difficult to distinguish from the counterpart benign tumor (eg, well-differentiated liposarcoma, well-differentiated leiomyosarcoma)
Score 2: Sarcomas for which histologic typing is certain (eg, myxoid liposarcoma, myxofibrosarcoma)
Score 3: Embryonal sarcomas and undifferentiated sarcomas, synovial sarcomas and sarcomas of doubtful tumor type
Tumor differentiation is the most problematic aspect of the FNCLCC system. Its use is subjective and does not include every subtype of sarcoma. Nevertheless, it is an integral part of the system, and an attempt should be made to assign a differentiation score.
Table 2. Tumor Differentiation Score According to Histologic Type in the Updated Version of the
French Federation of Cancer Centers Sarcoma Group System
Tumor Differentiation
|
Histologic Type |
Score |
|
Well-differentiated liposarcoma |
1 |
|
Well-differentiated leiomyosarcoma |
1 |
|
Malignant neurofibroma |
1 |
|
Well-differentiated Fibrosarcoma |
1 |
|
Myxoid liposarcoma |
2 |
|
Conventional leiomyosarcoma |
2 |
|
Conventional MPNST |
2 |
|
Conventional fibrosarcoma |
2 |
|
Myxofibrosarcoma |
2 |
|
Myxoid chondrosarcoma |
2 |
|
Conventional angiosarcoma |
2 |
|
High-grade myxoid (round cell) liposarcoma |
3 |
|
Pleomorphic liposarcoma |
3 |
|
Dedifferentiated liposarcoma |
3 |
|
Rhabdomyosarcoma |
3 |
|
Poorly differentiated/pleomorphic leiomyosarcoma |
3 |
|
Poorly differentiated/epithelioid angiosarcoma |
3 |
|
Poorly differentiated MPNST |
3 |
|
Malignant Triton tumor |
3 |
|
Synovial sarcoma |
3 |
|
Mesenchymal chondrosarcoma |
3 |
|
Extraskeletal osteosarcoma |
3 |
|
Extraskeletal Ewing sarcoma |
3 |
|
Malignant rhabdoid tumor |
3 |
|
Clear cell sarcoma |
3 |
|
Epithelioid sarcoma |
3 |
|
Alveolar soft part sarcoma |
3 |
|
Undifferentiated (spindle cell and pleomorphic) sarcoma |
3 |
Note: Grading of malignant peripheral nerve sheath tumor, embryonal and alveolar rhabdomyosarcoma, angiosarcoma, extraskeletal myxoid chondrosarcoma, alveolar soft part sarcoma, clear cell sarcoma, and epithelioid sarcoma is not recommended.4 The case for grading malignant peripheral nerve sheath tumor is currently being debated.
Modified with permission from Coindre JM.7
Mitosis Count: The count is made in the most mitotically active area, away from areas of necrosis, in 10 consecutive high-power fields (HPF) (1 HPF x 400 = 0.1734 mm2) (use the X40 objective). The area of 1 HPF originally used for mitotic count measured 0.1734 mm2. However, the area of 1 HPF using most modern microscopes with wider 40x lenses will most likely be higher. Pathologists are encouraged to determine the field area of their 40x lenses and divide 0.1734 by the obtained field area to obtain a conversion factor. The number of mitotic figures in 10 HPF multiplied by the obtained conversion factor and rounded to the nearest whole number should be used for grading purposes. If the mitotic rate is close to the cutoff between mitotic scores, the count should be repeated.
Score 1: 0 to 9 mitoses per 10 HPF
Score 2: 10 to19 mitoses per 10 HPF
Score 3: >19 mitoses per 10 HPF
Tumor Necrosis: Evaluated on gross examination and validated with histologic sections.
Score 0: No tumor necrosis
Score 1: <50% tumor necrosis
Score 2: ≥50% tumor necrosis