[Chondroblastoma].

Chondroblastomas are very rare benign primary bone tumors occurring preferentially in the epiphyses or apophyses of long bones in children and adolescents. In most cases the typical histological and imaging findings lead to a correct diagnosis that may be substantiated by demonstrating the highly specific point mutation in the H3F3B gene (p.K36M), either by sequencing or immunohistochemistry. Recurrences occur in 5-15% of cases, postsurgical metastatic deposits to the lungs are very rare (<1%). Histologically "malignant" chondroblastomas have been reported as single case reports. The treatment of choice is a thorough curettage, also in the case of local relapses.