Although osteoma is seen occasionally in the frontal sinus its occurrence in the ethmoidal sinus is rare.
The authors report a large osteoma of the ethmoidal sinus, which was associated with visual disturbance.
A survey of 2, 500 randomly selected x-ray films of the paranasal sinuses taken at the Jikei University Hospital and its affiliated hospitals revealed 3 osteomas of the paranasal sinuses including the present case, which was 0.12% in incidence.
The other two cases were osteomas in the frontal sinus.
Diagnosis of osteoma can be made either by x-ray, CT scan or isotope study, or by combination of these studies.
The present osteoma has been successfully removed by lateral rhinotomy with full recovery of the vision.