Assessment of Interobserver Variability and Histologic Parameters to Improve Reliability in Classification and Grading of Central Cartilaginous Tumors

Abstract

The distinction between benign and malignant cartilaginous tumors of bone is one of the most difficult subjects in surgical pathology. The grading of chondrosarcoma also seems to vary considerably among pathologists. However, clinical management differs. The purpose of this study was (1) to investigate interobserver variability in histological diagnosis and grading of central cartilaginous tumors and (2) to assess the diagnostic value of defined histologic parameters in differentiating enchondroma and central grade I chondrosarcoma. The interobserver variability was assessed using a set of 16 cases evaluated by 18 specialized pathologists. Subsequently, 20 enchondromas and 37 central grade I chondrosarcomas diagnosed in a multidisciplinary team with full clinical, radiologic, and pathologic data available with 10 years of follow-up were collected. Cytologic and tissue-architectural features were assessed to find an optimal set of parameters to differentiate enchondroma from central grade I chondrosarcoma. We demonstrate considerable variation in the histologic assessment of cartilaginous tumors (weighted kappa=0.78). The distinction between enchondroma and grade I chondrosarcoma was shown to be the most disconcordant (kappa coefficient=0.54), and also the differentiation between grade I and grade II chondrosarcoma was subjected to variation (kappa coefficient=0.80). The application of a combination of 5 parameters (high cellularity, presence of host bone entrapment, open chromatin, mucoid matrix quality, and age above 45 y) allowed optimal differentiation between enchondromas and central grade I chondrosarcomas. With a classification tree based on 2 parameters (mucoid matrix degeneration more than 20% and/or host bone entrapment present), 54 of the 57 (94.7%) cases were assessed correctly (sensitivity 95% and specificity 95%). Our study confirms the low reliability of the diagnosis and grading of central chondrosarcoma. However, these classifications guide therapeutic decision making in daily practice. Therefore, we propose a classification model that, combined with a tailored radiologic assessment, may improve reliability of the diagnosis of cartilaginous tumors.

Is Needle Biopsy Clinically Useful in Preoperative Grading of Central Chondrosarcoma of the Pelvis and Long Bones?

“…Similar results are described in the literature, where concordance between histological grade in preoperative biopsy and the final pathological analysis varies from 65% to 86% [8,13,24,25,27]. In our study, the concordance between needle biopsy and surgical specimen for histological grade, in pelvic chondrosarcomas, was poor (36% [14 of 39]), in agreement with other published studies [15,21].…”

“…Although histological patterns for enchondroma and chondrosarcoma have been well described, they are not easy to recognize in small biopsies and the diagnosis is nearly always made with the support of clinical and radiological findings [2,5,7,8,11,14,22,27]. Not only can the distinction between benign and malignant be misleading, but also the grading of malignant lesions may differ significantly, even among experts [8,25]. Although some studies demonstrate that radiological imaging [2,5,7] may be used to differentiate low-grade chondrosarcomas from highgrade ones, definitive grading still relies on histological features.…”

“…There is considerable interobserver variability among pathologists when dealing with cartilaginous tumors [8,22,23]; therefore, the role of preoperative biopsy has been controversial. Clinical manifestations and radiological features are used, alone or correlated with histology, to make therapeutic decisions [2,5,7,11,14,22,27].…”

Insights into Enchondroma, Enchondromatosis and the risk of secondary Chondrosarcoma. Review of the literature with an emphasis on the clinical behaviour, radiology, malignant transformation and the follow up

“…The overlap in appearance between benign lesions and low-grade cartilage tumors has led to a high rate of inter-and intraobserver variability in diagnosis [62]. Therefore, information from the clinical history and imaging studies must be correlated with the pathologic data to render the correct diagnosis [3,63].…”

No Recurrences in Selected Patients after Curettage with Cryotherapy for Grade I Chondrosarcomas

“…Extensive excision minimizes the possibility of recurrences and metastases but often is mutilating; diaphyseal tumors require allograft reconstruction [9] and metaphyseal and epiphyseal tumors require the use of a prosthesis [12,14]. Such aggressive treatment contrasts with the generally indolent growth of these low-grade tumors, which often are discovered by chance [15] and sometimes are mistaken for atypical enchondromas [4,14]. Although there formerly was a tendency to opt for aggressive surgery, there now is a trend toward Frantz Langlais-Deceased.…”