The underlying lesion is multilocular and extends through the medullary cavity, features which favor aneurysmal bone cyst over unicameral bone cyst or non-ossifying fibroma. MRI can help narrow the differential diagnosis by demonstrating fluid-fluid levels but in this case sampling at the time of fixation may be more appropriate.

In children, pathological fractures are often secondary to benign disease. Nevertheless, a malignant condition must always be formally ruled out.

Long above knee back slab cast applied prior to orthopedic review.