Distal Femoral Non-Epiphyseal Cortical Chondroblastoma Confirmed with p. Lys36Met Mutation.

Chondroblastoma is a primary bone tumor typically arising from the intramedullary space of the epiphysis or epimetaphysis. A non-epiphyseal chondroblastoma is uncommon. An 11-year-old girl presented with an eccentric cortical osteolytic lesion in the distal femur metaphysis. The typical morphology, diffuse H3.3 K36M immunohistochemical expression and point mutation () unequivocally supported the diagnosis of chondroblastoma. We described a non-epiphyseal cortical-based chondroblastoma involving the distal femur harboring the typical mutation. Non-epiphyseal chondroblastoma may harbor the mutation.