Chondroblastomas presenting in adulthood: a study of 39 patients with emphasis on histological features and skeletal distribution.

Abstract

Chondroblastomas (CB) are rare bone tumours that typically arise in the epiphysis/apophysis of long bones in skeletally immature patients. We explore the clinicopathological features of CB presenting in adults. CB in patients ≥20years of age were retrieved from our institutional archives. Thirty-nine CB were identified (29 male/10 female; aged 20-54years). Twenty (51%) cases occurred in long tubular bones, 10 (26%) in small bones of the feet, five (13%) in flat bones and four (10%) in the patella. All cases showed classic cytological features of CB, and chondroid matrix was universally present. Calcification was identified in 10 cases (26%), including various combinations of serpiginous (n=7), punctate (n=6), classic chicken-wire (n=4) and psammomatous (n=2) patterns. Haemosiderin (n=19), woven bone (n=13), secondary aneurysmal bone cyst formation (n=8), foamy macrophages (n=4), hyalinised vascular spaces (n=2) and cholesterol clefts (n=2) were noted. Follow-up information (n=32, 1-452months) revealed local recurrence in three patients, all >40years of age with flat bone origin, one of which developed pulmonary metastases 132months after initial diagnosis. CB in patients >20years of age more frequently involves the short bones of the hands/feet and flat bones compared to those arising in their younger counterparts. A subset may harbour extensive serpiginous or psammomatous calcification rather than the classic chicken-wire pattern. Although the overall local recurrence rate in adulthood is approximately 10%, all three patients with recurrent disease had tumours involving flat bones, suggesting that tumours arising in these sites may behave more aggressively.