Tumour lesion characteristics for aneurysmal bone cysts and osteoid osteomas. Radiographic image of an aneurysmal bone cyst (ABC) detected in the proximal part of the forth digit (A). Histological investigation (B) revealed blood-filled cystic spaces and numerous osteoclasts and hemosiderophage within the cyst walls. Locations of ABCs in the hand identify phalanges as the site most affected (C). Prevalence was mostly in the first four decades. (D). An osteoid osteoma of the thumb is displayed radiographically (E). Number of cases and their distribution are displayed in part G. Osteoid osteomas were mostly found in the second to fourth decade (H). The tumours were characterised by cellular bone forming neoplasm without atypia (F).