Clear cell chondrosarcoma: case report and ultrastructural study

Clear cell chondrosarcoma is an underestimated tumor: Report of 7 cases and meta-analysis of the literature

Introduction

Clear cell chondrosarcoma (CCC) is a rare subtype of chondrosarcoma and it is commonly considered a low-grade tumor and less aggressive than atypical cartilaginous tumor (grade 1 central chondrosarcoma). However, the experience even of musculoskeletal tumor centres with this rare entity is limited. The aim of this study is to analyse our own treatment results and those of the literature regarding the therapy and outcome of this lesion.

Material and Methods

7 cases of CCC have been treated in our department between 2003 and 2015. Their follow-up data were collected retrospectively. 187 literature cases with histopathological and clinical characteristics were retrieved by means of a PubMed search with the key word “clear cell chondrosarcoma”. The data pertaining to treatment and follow up were extracted. We analysed the survival of patient and the risk factors for local recurrence (LR) as well as metastatic disease (MD).

Results

The mean age at the time of diagnosis was 40 years. Two thirds of the patients were male. The mean follow-up time was 109 months. To our surprise, there was a high rate of LR (30%) and of MD (20%) when compared to low-grade conventional chondrosarcomas. 15% of LR and 20% of metastatic disease were observed after more than 10 years follow-up. Uncommon locations of MD such as in the spine is a unique observation in chondrosarcomas and underlines the high aggressiveness of this tumor. 10-year overall survival was almost 80%, 10-years disease free survival 60%. Positive margins (p = 0.038) and metastases (p = 0.006) impaired the overall survival significantly. The rate of local recurrence was significantly dependent on resection margin (p < 0.001); however there was no correlation with the grade of differentiation of the tumor. The development of MD was affected by local recurrence (p = 0.006), but we could not detect a significant association with margin status (p = 0.184).

Conclusions

A wide resection is the advocated treatment option. Long term follow-up for at least 10 years is necessary in order to not overlook late LR or MD. This work demonstrates for the first time the apparent aggressiveness of the CCC.

Aggressive clear cell chondrosarcomas: do distinctive characteristics exist?: a report of 4 cases

CONTEXT

Clear cell chondrosarcoma (CCC) is commonly considered to be a low-grade subtype of chondrosarcoma. However, a few cases of CCC behave as high-grade lesions (with early metastases or multiple/synchronous locations).

OBJECTIVE

To investigate morphologic features that can help predict the aggressiveness of these CCCs.

DESIGN

To investigate possible hallmarks of this aggressiveness, we are presenting the clinicopathologic features of 6 cases of CCC, 4 of which presented aggressive features and 2 low-grade behavior. The patients were 5 men and 1 woman; their ages ranged from 22 to 47 years. Histologic appearance, ultrastructure, and immunohistochemical expression of metalloproteinase 1 and 2 and their inhibitors were evaluated in all 6 cases.

RESULTS

Pain was the most common symptom; the lesions were located in the femur (4), humerus (2), and vertebral body (1), with 1 patient presenting a double/synchronous lesion. Although no major differences were detected using conventional light microscopy, an ultrastructural analysis--at variance with usual cases--showed a lack of superficial microvilli in more than 50% of neoplastic cells in the aggressive cases, therefore suggesting a less differentiated phenotype. In addition, metalloproteinase 2 was more diffusely expressed in the aggressive tumors than in the conventional CCCs, whereas p53 labeling was always negative.

CONCLUSIONS

The aggressive behavior of some CCCs may be, at least in part, correlated to a lesser degree of cell differentiation and to the expression of tumor cell proteins, such as metalloproteinase 2, which are able to favor neoplastic spreading.