A new scoring system for the grading of conventional chondrosarcoma: Its clinicopathological significance

Yosuke Susuki; Yuichi Yamada; Yoshihiro Ito; Kengo Kawaguchi; Hiroshi Furukawa; Kenichi Kohashi; Izumi Kinoshita; Kenichi Taguchi; Yasuharu Nakashima; Yoshinao Oda

doi:10.1016/j.prp.2022.154125

A new scoring system for the grading of conventional chondrosarcoma: Its clinicopathological significance

Pathol Res Pract. 2022 Oct:238:154125. doi: 10.1016/j.prp.2022.154125. Epub 2022 Sep 16.

Affiliations

¹ Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
² Division of Orthopaedic Oncology, Kyushu Cancer Center, 3-1-1 Notame, Minami-ku, Fukuoka 811-1395, Japan.
³ Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
⁴ Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Electronic address: oda.yoshinao.389@m.kyushu-u.ac.jp.

PMID: 36174441
DOI: 10.1016/j.prp.2022.154125

Abstract

Background: Chondrosarcoma is the second most common primary malignant bone tumor, which produces cartilaginous matrix without neoplastic osteoid or bone formation. The histological grade in the WHO Classification of Soft Tissue and Bone (2020 edition) is the most important factor in predicting the clinical outcome of conventional chondrosarcoma, but the lack of clarity in its detailed definition is occasionally problematic. Here, we reviewed conventional chondrosarcoma cases and validated the significance of histological findings. Moreover, we proposed a new scoring system of conventional chondrosarcoma.

Material and methods: Clinicopathological features of 60 cases of conventional chondrosarcoma and 21 cases of dedifferentiated chondrosarcoma were reviewed.

Results: Moderate to severe nuclear atypia was correlated with distant metastasis. Moderate and severe nuclear atypia, high cellularity, and >1 % myxoid change were correlated with adverse overall survival. On the other hand, cases with mild nuclear atypia showed no tumor-related death and no metastases. Based on the above results, we proposed a new scoring system based on nuclear atypia (mild: 0, moderate: +1, severe: +2), cellularity (no and mildly increased cellularity: 0, moderately and diffusely increased cellularity: +1), necrosis [(-): 0, (+): + 1], and chondromyxoid area [(-): 0, (+): + 1]. Each grade was defined as follows: cases with only mild nuclear atypia as grade 1, cases with total score 1-3 excluding mild nuclear atypia as grade 2, and cases with total score 4 or 5 as grade 3. There were 18 cases (30 %) of grade 1 including 5 cases (28 %) of local recurrence, but no metastasis or tumor-related death; 26 cases (43 %) of grade 2 including 2 cases (8 %) of local recurrence, 3 cases (12 %) of metastasis, and 1 case (4 %) of tumor-related death; and 16 cases (27 %) of grade 3 including 4 cases (25 %) of local recurrence, 6 cases (38 %) of metastasis, and 5 cases (31 %) of tumor-related death. There was no statistically significant association between the histological findings and dedifferentiation.

Conclusion: From this study, we propose a new histological scoring system for the grading of conventional chondrosarcoma, based on nuclear atypia, cellularity, necrosis, and myxoid change. Using this system, conventional chondrosarcoma may be clearly classified into three grades: grade 1, non-metastasizing; grade 2, metastasizing but rarely life-threatening; and grade 3, frequently metastasizing and life-threatening.

Keywords: Chondrosarcoma; Dedifferentiation; Grading.