Orbital rhabdomyosarcoma presenting as an apparent orbital subperiosteal abscess.

We present a patient with acute sinusitis whose CT scan showed a ring-enhancing lesion within the orbit typical of an orbital subperiosteal abscess. On exploration of the orbit, there was no pus present but a tumour was found, which on histological examination was found to be a rhabdomyosarcoma. The clinical signs and CT characteristics of orbital subperiosteal abscesses and rhabdomyosarcomas are discussed. A ring-enhancing lesion within the orbit on CT scan should not be regarded as being pathognomonic for a subperiosteal abscess and the possibility of other diagnoses should be considered.