Presumed, Adult-onset Eosinophilic Granuloma of the Orbital Roof Showing Spontaneous Resolution

Aims: To describe an unusual case of presumed, adult-onset eosinophilic granuloma of the orbital roof, which showed spontaneous resolution.

Presentation of Case: A 42-year-old man presented with a three-month history of relapsing oedema in his right upper eyelid. Slit-lamp examination of both eyes was unremarkable, ocular motility was normal, and there was no proptosis. CT and MRI head scans disclosed a 15mm solid mass in the right anterior cranial fossa, which had eroded the orbital roof and penetrated into the orbit. An initial diagnosis of orbital intradiploic meningioma was made. Total resection of the lesion was planned and the patient was put on the waiting list for neurosurgery. One year later, preoperative MRI disclosed a significant regression of the lesion. Six months later, CT and MRI showed complete disappearance of the lesion and full re-ossification of the orbital roof. A presumptive, final diagnosis of eosinophilic granuloma was made and the patient was cancelled from the waiting list for neurosurgery. There have been no MRI changes in the last 24 months.

Discussion: In this report, initial radiological images were apparently consistent with an orbital intradiploic meningioma. However, this diagnosis turned out to be wrong, because spontaneous resolution of adult-onset orbital intradiploic meningioma has never been reported. Conversely, orbital eosinophilic granuloma may heal without treatment, even though its occurrence in adults is exceptional.

Conclusion: Upper eyelid oedema may be the presenting sign of an osteolytic intracranial mass eroding the orbital roof and extending into the orbit. Radiological differential diagnosis may be difficult. In adults, the detection of an osteolytic lesion and its subsequent spontaneous resolution may be suggestive of an eosinophilic granuloma.