An expanding cystic mass lesion is seen arising from the right anterior ethmoidal air cells, extending and overlying the right maxillary antrum with thinning out of the sinus outlines. It breaks through the right posterolateral and inferior orbital wall and elevates the orbital floor with consequent proptosis. Consequent displacement of the inferior rectus muscle up and posterior aspect of the optic nerve medially. The lesion extends up with the erosion of the floor of the anterior cranial fossa with intracranial extra-axial extension.