John I, et al. - Data of chondroblastomas (CB, rare bone tumors that typically arise in the epiphysis/apophysis of long bones in skeletally immature people) in individuals ≥ 20 years of age was pooled from an institutional archives and 39 CB were recognized in order to investigate the clinicopathological characteristics of CB presenting in adults. In comparison with those arising in their younger counterparts, CB in individuals > 20 years of age more often included the short bones of the hands/feet and flat bones. Rather than the classic chicken-wire pattern, a subset may harbor extensive serpiginous or psammomatous calcification. However, in adulthood, the overall local recurrence rate was nearly 10%, all three individuals with recurrent disease had tumors including flat bones, implying that tumors arising in these sites may function more aggressively.