The role of periostin and PEG10 biomarkers in thediagnosis of degree 1 chondrosarcoma and enchondroma

Introduction and Aim: Chondrosarcoma (CS) is the most common primary malignant bone tumor after osteosarcoma. It is divided into five subgroups as classic, clear cells, periosteal, mesenchymal and dedifferentiate. These include a conventional CS at a rate of 90 %. Conventional CS is divided into three degrees. Histomorphologically, it is relatively easier to dicern degree 2 and 3, while histopathological distinction of between degree 1 CS solely from the enchondroma is often difficult and sometimes impossible. Enchondroma is a benign tumor of the bone and its treatment is usually followed, whereas the treatment of grade 1 CS is excision with safe surgical margins. There is no immunhystochemical marker to safely distinguish between these two tumors with different treatment and prognosis. With this study, in the last 16 years, we have examined the place of periostin and PEG10 immunhistochemical markers in the distinction between cases diagnosed with degree 1 CS and enchondroma. Materials and Methods: All cases diagnosed with enchondroma and grade 1 CS in the Pathology Department of Ondokuz Mayıs University Faculty of Medicine between 2005 and 2021 were included in the study. Hematoxylin-eosin sections of the cases were re-evaluated and the diagnoses were confirmed. The evaluation was based on the 2020 WHO classification. Buffered neutral formalin fixed tissues were processed to obtain paraffin blocks and sections of 4 micron thickness were taken on positively charged slides (Menzel, Superfrost Plus Slides); secetions were deparaffinized, then anti-Periostin antibody (ABCAM/ab215199) and anti-PEG10 antibody (ABCAM/ab215035) with immunohistochemical staining was performed on a LT Ventana Benchmark device. Statistical evaluations were made with SPSS software. Results: 50 of the 91enchondroma cases included in the study are women and 41 are males; 27 degrees 1 CS cases are women and 17 are males. The most common location in enchondroma was hand-phalanx and for degree 1 CS humerus. Of the cases with fallow up information recurrence was observed in 1 of 34 enchondromas and 4 of 14 degree 1 CS cases. No staining was observed with either periostin nor PEG10 in any of the 91 enchondromas and 27 degree 1 CSs. Discussion and Conclusion: Despite controlling any pre-analytic technical problems and using different antigen retrieval protocols at the analytical stage, staining with periostin or PEG10 was not observed. At this stage, it was concluded that periostin and PEG10 antibodies were not beneficial in the distinction between enchondroma and CS, at least with the clones used.