Giant osteoid osteoma of the ethmoid bone with unusual large nidus

Osteoid osteoma (OO) is a benign bone neoplasm which is seen in the long bones of appendicular skeleton. It is rarely seen in the cranium. Ethmoid bone OO has been very rarely reported so far. We report another case of giant osteoid osteoma involving the ethmoid bone with intraorbital and intracranial extension in a 3O year old female patient. This case with unusual anatomical location was presented. It is first time reporting a giant osteoid osteoma of ethmoid bone with such a large nidus.