FNCLCC grading system
（FNCLCC, Fédération Nationale des Centres de Lutte Contre le Cancer）
欧州のフランスから提唱された、軟部肉腫の組織学的悪性度評価方法である。
Tumor differentiationは、その腫瘍の中で最も未分化な部分を評価して行われるが、実際は評価が難しいので、Table 2のように組織型毎にScoreが決められている。Table 2は筆者がWHO blue book (IARC)及びAJCC Cancer Staging Manual, 7th ed (Springer)を合成した形で作成している。組織型によっては、このスコアシステムを推奨しないとの立場をとるものもある。詳しくは以下の文献を御参照いただきたい。
Table 1. Definition of histological parameters in the FNCLCC grading system
| Histological parameter | Definition |
| Tumor differentiation | See Table 2 |
| Score 1 | Sarcomas closely resembling normal adult mesenchymal tissue and potentially difficult to distinguish from the counterpart benign tumor (e.g. well-differentiated liposarcoma, well-differentiated leiomyosarcoma) |
| Score 2 | Sarcomas for which histological typing is certain (e.g. myxoid liposarcoma, myxofibrosarcoma) |
| Score 3 | Embryonal and undifferentiated sarcomas, synovial sarcomas, sarcomas of doubtful type |
| Mitotic count | |
| Score 1 | 0-9 mitoses per 10HPF |
| Score 2 | 10-19 mitoses per 10HPF |
| Score 3 | >19 mitoses per 10HPF |
| Tumor necrosis | |
| Score 0 | no necrosis |
| Score 1 | <50% tumor necrosis |
| Score 2 | ≧50% tumor necrosis |
| Histologic grade | |
| Grade 1 | total score 2,3 |
| Grade 2 | total score 4,5 |
| Grade 3 | total score 6,7,8 |
| HPF, high-power field; 1HPF measures 0.1734 mm2 | |
Table 2. Tumor differentiation score according to histological type in the FNCLCC grading system
| Histological type | Differentiation score |
| Atypical lipomatous tumor/Well-differentiated liposarcoma | 1 |
| Myxoid liposarcoma | 2 |
| Round cell liposarcoma | 3 |
| Pleomorphic liposarcoma | 3 |
| Dedifferentiated liposarcoma | 3 |
| Well-differentiated leiomyosarcoma | 1 |
| Conventional leiomyosarcoma | 2 |
| Poorly differentiated/pleomorphic leiomyosarcoma | 3 |
| Epitheloid leiomyosarcoma | 3 |
| Well-differentiated fibrosarcoma | 1 |
| Conventional fibrosarcoma | 2 |
| Myxofibrosarcoma (myxoid MFH) | 2 |
| Typical storiform MFH (sarcoma, NOS) | 2 |
| MFH, pleomorphic (patternless pleomorphic sarcoma) | 2 |
| Giant cell and inflammatory MFH | 3 |
| Malignant neurofibroma | 1 |
| Conventional MPNST | 2 |
| Poorly differentiated MPNST | 3 |
| Myxoid chondrosarcoma | 2 |
| Mesenchymal chondrosarcoma | 3 |
| Conventional angiosarcoma | 2 |
| Poorly differentiated/epithelioid angiosarcoma | 3 |
| Rhabdomyosarcoma | 3 |
| Malignant Triton tumor | 3 |
| Synovial sarcoma | 3 |
| Extraskeletal osteosarcoma | 3 |
| Extraskeletal Ewing sarcoma/PNET | 3 |
| Clear cell sarcoma | 3 |
| Epithelioid sarcoma | 3 |
| Alveolar soft part sarcoma | 3 |
| Malignant rhabdoid tumor | 3 |
| Undifferentiated (spindle cell and pleomorphic) sarcoma | 3 |
文献：
1. Coindre JM. Grading and staging of sarcomas. In: Fletcher CDM, Bridge JA, Hogendoorn PCW, Mertens F. WHO classification of tumours of soft tissue and bone. 4th ed. Lyon; IARC Press, 2013. pp.17-8.
2. Guillou L, et al. Comparative study of the National Cancer Institute and French Federation of Cancer Centers Sarcoma Group grading systems in a population of 410 adult patients with soft tissue sarcoma. J Clin Oncol 1997;15:350-62.
3. Edge SB, Byrd DR, Compton CC, Fritz AG, Greene FL, Trotti III A, eds. AJCC Cancer Staging System. 7th ed. Chicago; Springer, 2010. pp.293-4.
執筆日：2013/06/27
執筆者：神戸大学医学部附属病院病理診断科 酒井康裕
