Recurrent chondroblastoma of the acetabulum in an adult.

Chondroblastoma is a rare, benign neoplasm of chondroblast cell origin, accounting for less than 1% of primary bone tumors. It is usually diagnosed in the second decade of life with most of the cases involving the long bones such as the femur and humerus. Furthermore, over 90% of cases are in individuals under 30 years of age. In older adults, chondroblastomas are typically found in bones in the foot, such as the talus and calcaneus. Treatment is usually local curettage of the lesion with a relatively low rate of recurrence. In this case report, we present a patient with an atypical age of initial presentation at 49 years, a rare location of the chondroblastoma in the acetabulum, and a recurrence 14 years after surgical resection in the same location. The lesion's radiographic findings of intralesional calcifications alongside the high-signal, heterogeneous composition on T2-weighted MRI were supportive of the atypical diagnosis of chondroblastoma in this patient.