Recurrent 12q13-15 chromosomal aberrations, high frequency of isocitrate dehydrogenase 1 mutations, and absence of high mobility group AT-hook 2 expression in periosteal chondromas.

Periosteal chondroma is a benign cartilage tumor that accounts for <2% of chondromas. In the present study, four cases of periosteal chondromas were cytogenetically investigated and studied for the expression of high-mobility group AT-hook 2 (HMGA2), mutations in codons 132 of isocitrate dehydrogenase (IDH)1 and 172 of IDH2; mutations -C228T and -C250T in the promoter region of telomerase reverse transcriptase (TERT); and for methylation in the promoter regions of O-6-methylguanine-DNA methyltransferase (MGMT) and cellular retinol binding protein 1 (CRBP1). Chromosome aberrations of 12q13-15 were found in two out of the four tumors, while two had a normal karyotype. Two periosteal chondromas carried the mutation IDH1R132C (CGT>TGT), and two carried the mutation IDH1R132L (CGT>CTT). However, none of the four tumors had methylated MGMT and CRBP1 promoters or mutations at codon 172 of IDH2. In addition, -C228T and -C250T mutations were not present in the promoter region of TERT, nor was HMGA2 demonstrated to be expressed. The present study indicated that in periosteal chondromas, the involvement of 12q13-15 in structural rearrangements may be recurrent but that HMGA2 is not expressed. Additionally, the periosteal chondromas investigated in the study carried a heterozygous IDH1R132 mutation, the MGMT and CRBP1 promoters were not methylated, and -C228T and -C250T mutations in the promoter region of TERT were absent.