Cherubi sm is a ra re autosoma l dominant inherited condi tion caused by mutations in the c-Abl-binding protein SH3BP2. 1t is characteri zecl by mul t iple cystic giant cell lesions of the jaw appearing in early childhood with stabi li zation and rcmi ssion after pubcr ty, In thc present study, genomic DNA was purified f rom a blood sample obtained from the patient a ncl pa rents a ncl used f'or di rect sequence analysis of the SH3BP2 gene, 1n addit ion, a sample of the lesion was used f0 1" hi stologic ancl immunoh is toche mical purposes, Histology revealed a proliferation of spindle s haped fibroblas t ic cells and irregu la ry dis persed multinucleated giant cell s , The multinucleated giant cells proved posit ive for CD68 and TRAP, Ge nomic DNA sequencing f'ou ncl a missense mutation Pro418Arg in exon 9 of the SH3BP2 gene of the patient and the mother, Theref'ore, the mul t inucleated giant cells are basically osteoclastic in nature, Additionally, as the PI'o418Arg mutation had been repol' ted as caus ing cherubism, it represents a mutational hotspot,