Parasinusal osteoma complicated by intracranial and orbit extension, cranial vault hyperostosis, intracranial mucocele and inflammatory pseudotumor is exceptional. A 68-year-old man complaining a long history of progressive proptosis and recurrent episodes of keratoconjunctivitis of the left eye, with restriction in upward gaze, was observed. Contrast-enhanced magnetic resonance imaging revealed a frontal sinus lesion extending to the left anterior fossa and orbit, featuring intracranial cystic component and heterogeneous contrast-enhancement. Head computed tomography confirmed the double calcific-cystic nature of the lesion. A left supraorbital-pterional approach allowed the complete resection of mucocele and drilling of intracranial and orbital osteoma, including the intra-sinusal component. The frontal sinus was cranialized and a flap of pericranium, reinforced by Gelfoam sponge, was reflected on the anterior cranial base/orbital roof. The postoperative course was uneventful; MRI depicted resolution of the proptosis. The histologic examination was in favor of parasinusal osteoma associated to intracranial mucocele, frontal bone hyperostosis and inflammatory pseudotumor.