the 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 correlation between giant cell tumor in hereditary multiple exostosis is still not clearly determined . a 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 . giant cell tumor and hereditary multiple exostosis also demonstrated associations of chromosomes 11 with a different pathological process . giant 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 . it often characterized by osteolytic destruction at the end of a long bone and large multinuclear cells in its histologic appearance . it is benign in nature and known to be able to both recur and transform into malignancy , , . the malignant subtype of gct is usually expressed some genes like the b - cell lymphoma 2 ( bcl-2 ) gene . the gct was rarely found in coexistence with other benign lesion such as hereditary multiple exostosis ( hme ) , . the reason behind that coexistence is still unclear , whether caused by either a transformation of hme or only considered as two separated lesions . hereditary multiple exostosis is an autosomal dominant condition which characterized by the development of multiple exostosis and possess interfamilial and intrafamilial phenotypical variability in severity , size , and number of lesions . this hme lesions are primarily caused by the presence of exostosin-1 ( ext-1 ) gene that occur in approximately 90% of cases . the aim of this report is to identify the bcl-2 and ext-1 gene in gct with coexistence of hme . it also served as a preliminary research to prove that the gct with the expression of ext-1 and bcl-2 in patients with hme tend to be more aggressive with high local recurrence and worse prognosis . a 31-years - old female presented with pain and lump on her left wrist since 4 months ago . physical examination revealed a lump located on left wrist . the size of the lump clinically was 5  cm by 6  cm with shiny skin , clear border , firm in consistency , and fixed to the bone ( fig . her wrist extension and flexion was limited to 10 of flexion and 5 of extension due to pain and mass . on the right and left knees , we found non - tender multiple lumps ( fig . 1b ) . the x ray of left wrist revealed osteolytic lesion with some geographic patterns ( fig . she had wide surgical excision of the tumor which extended to the wrist joint and 3  cm upper the tumor followed by reconstruction using non vascularized fibular graft . we found multiple bony masses with clinical characteristics of multiple exostosis on the proximal site of fibular graft ( fig . the excised part of the radius has replaced with non - vascularized fibular graft , then fixed with plate and screws . histopathological finding revealed gct with an eosinophilic cytoplasm , round ovals nucleus , vesicular chromatin with small nucleus prominent , and a slight mitosis ( fig . 3 ) . immunochemistry finding revealed existence of ext-1 but no existence of bcl-2 ( fig . the patient feels no pain , already returned to regular activities , range of motion return to 7599% and the grip strength is 100% ( fig . the case presented a gct of the left wrist with another lesion of hme on the right and left knee . this case was very rare because we were not able to find more cases in the literature matching this coexistence . ( 2002 ) mentioning a coexistence of giant cell tumor over the left leg , para - articular osteochondroma over the left hip and an idiopathic thrombocytopenic purpura ( itp ) . a curettage of gct lesion was performed , followed by washing out the remainder with hot saline , then filled with autogenous iliac bone graft and cement . ( 2015 ) has reported a case of gct of proximal tibia in patient with history of multiple osteochondromatosis . the tumor was resected , a skeletal reconstruction with gmrs prosthesis was performed , followed by soft tissue reconstruction with rotation flap . histopathological examination revealed gct with area of fibrohistiocytic pattern and component of aneurysmal bone cyst . the report also suggested a positive genetic polymorphism in the ext-2 gene . in this case , we suspected the existence of two tumors in one patient . there was revealed a positive expression of ext-1 gene and negative expression of bcl-2 gene from gct mass of left wrist . the cells giving positive reaction of anti - ext-1 with b chomogen method ( fig . positive reaction was pointed by blue arrow , on the other hand , negative reaction was represented by red arrow . positive control showed coloration on nucleus and cytoplasm , whereas no coloration on nucleus and cytoplasm was found on negative as seen on fig . currently , ext-1 gene has considered as an important causative factor in hereditary multiple exostosis , , . hereditary multiple exostosis is genetically heterogeneous with three loci on chromosomes 8q24.1 , 11p13 , and 19q . the first ext-1 locus that located on chromosome 8 ( 8q24.1 ) was discovered by cook in 1993 , which also linked with chromosome 11q24 . the distal end of 8q locus is responsible for the formation of hme and was identified as the ext-1 . later on , a new gene on chromosome 11 ( 11p11 - 13 ) was identified as a locus for hme and named ext-2 . a third locus on chromosome 19p , suspected of causing hme was named ext-3 , but it is considered to be a minor contributor to the actual formation of hme . most of the ext-1 and ext-2 genes ( 80% ) prompt to mutation by nonsense , frameshift or splice - site mutations leading to premature termination of the ext proteins . giant cell tumor of the bone is a benign , primary skeletal neoplasm with variable biologic aggressiveness that demonstrates telomeric associations of chromosomes 11 , 16 , 19 , 20 , and 21 , reduction of telomere length , marker chromosomes , double minutes , chromosome fragments , ring chromosomes , and polyploidy . some gene that expressed in gct such as ip53 , h - ras , c - myc , mmp-9 , mib-1 and bcl-2 had important rules for malignant transformation   . we have also performed immunohistochemistry of bcl-2 for finding the apoptosis process in the tumor lesions . bcl-2 is an anti - apoptosis protein whose overexpression contributes to the uncontrollable proliferation of gliomas and other neoplasm s . it encodes an integral membrane protein ( 25  kda protein ) , mainly localized to inner mitochondrial membrane , endoplasmic reticulum and nuclear envelope . the bcl-2 overexpression increases lifespan of b cells , maintains memory b cells , plasma cells and neurons by prolonging life span without cell division . it also may participates in ion channel formation and alteration of membrane permeability that necessary for initiation of apoptosis . ( 2010 ) in their study reported a higher value of bcl-2 in malignant subtype of gct . this implies that malignant transformation could trigger gct cells to express this marker more frequently , thus , it could be regarded as an indicator for malignant transformation and unfavorable clinical course . ( 1998 ) studied expression of regulatory apoptotic proteins in peripheral giant cell lesions containing osteoclast - like giant cells that showing only weak positivity for bcl-2 . in this case the bcl-2 result is negative , revealing that the giant cell tumor was not transformed into malignant . based on the results of this study , gct characterized as benign aggressive with negative bcl-2 gene expression and showed similarity with hme by a positive ext-1 gene expression . a data based on ontology between hme and gct assuming that gct may arise from a transformation of hme . giant cell tumor in hereditary multiple exostosis revealed positive ext-1 without bcl-2 expression . in this case , this coexistence revealed a probability of gct that arised from hme but did not showed malignant transformation .