Chondroblastoma Case Study

INTRODUCTION
Chondroblastoma is an uncommon benign tumor accounting for less than 1% of bone tumors. It mainly involves the epiphysis or epimetaphysis of long bones.(1) Chondroblastoma with secondary aneurysmal bone cyst is a rare entity and only 13 cases have been reported in the literature reviewed. Ours is a case of calcaneal chondroblastoma with secondary aneurysmal bone cyst. Only two cases of calcaneal chondroblastoma associated with secondary aneurysmal bone cyst (ABC) has been reported till date in the literature reviewed.(1)(2)
CASE REPORT
A 22 year male presented in the orthopedic OPD with complain of pain and swelling in the left heel for 10 months. The pain was insidious in onset, dull aching and aggravated on walking or standing.

It occurs predominantly in 10-20 years of age. Males are affected more than the females. In 98% of cases the epiphysis of the long bones are involved. Common sites of involvement are proximal humerus (18%), proximal tibia (17%), proximal and distal femur (16%) and ankle bone (13%). Among the ankle bones talus and calcaneum are involved in 47% and 40% cases respectively.(3) Similar findings were reported in a study by the US Armed Forces Institute of Pathology (AFIP) in which 42 (13.04%) of 322 chondroblastomas diagnosed between 1985 and 1993 involved the foot. Out of these 17 (40.48% of chondroblastomas, or 5.28% of bone tumors) involved the calcaneus and 20 (47.62% of chondroblastomas, or 6.21% of bone tumors) involved the talus.(1) However the calcaneum involvement was only 6 (5.77%) out of 104 cases in one review by Bloem et al (4), and 0 out of 70 cases in another series by Turcotte et al (5). Chondroblastomas can be associated with aneurysmal bone cyst in 10-15% of cases. This association is more common in patients older than 20 years.(2) The identification of chondroblastoma with secondary ABC is important as it has more chance of recurrence than chondroblastoma.(1) According to Huvos et al the local recurrence was found to occur in all cases of chondroblastomas with associated ABC(6). Whereas the rate of recurrence observed in noncystic lesions is 10% to