Case ReportCase Report of the positive exostosin-1 without B-cell lymphoma-2 gene expression of giant cell tumor lesion in hereditary multiple exostosis

•The giant cell tumor is a benign, primary skeletal neoplasm with variable biologic aggressiveness.•A coexistence with hereditary multiple exostosis with expression of EXT-1 is very rare.•BCL-2 gene is expressed only in malignant transformation of the giant cell tumor.•The correlation between giant cell tumor and hereditary multiple exostosis is still not clearly determined.•The case revealed giant cell tumor in hereditary multiple exostosis with positive EXT-1 without BCL-2 expression.

IntroductionThe giant cell tumor, in which BCL-2 gene was expressed only in its malignant transformation, is a benign, primary skeletal neoplasm with variable biologic aggressiveness. The is of the giant cell tumor. A coexistence with hereditary multiple exostosis with expression of EXT-1 is very rare. The correlation between giant cell tumor in hereditary multiple exostosis is still not clearly determined.Presentation of caseA 31-years-old female presented with pain and lump on her left wrist and a coexistence of non tender multiple lump in the right and left knee. A wide excision of the tumor and reconstruction using non vascularized fibular graft was performed, followed by histopathology and immunohistochemistry of EXT-1 and BCL-2.DiscussionIn this case, the tumor showed negative BCL-2 and positive EXT-1 gene expression. Giant cell tumor and hereditary multiple exostosis also demonstrated associations of chromosomes 11 with a different pathological process.ConclusionGiant cell tumor in hereditary multiple exostosis revealed positive EXT-1 without BCL-2 expression. It still need more investigation to confirm the relationship between these tumors.