CLAVICLE - Aneurysmal bone cyst

The specimen is a clavicle from a child, and shows the upper end expanded by a part-fibrous and part-cystic structure, in which there are areas of haemorrhage. The periosteum still appears to be intact, although much of the cortex has been destroyed. As often happens, the histology of lesions such as this can be equivocal. This lesion showed features suggesting a benign giant cell tumour of bone, but with features also suggesting an aneurysmal bone cyst.
This patient has been lost to follow-up.