Introduction and importance:Osteoma is the most common benign tumor of the nose and paranasal sinuses. It is usually asymptomatic and diagnosed accidentally. In our case, the tumor formed in an unusual location and led to unexpected symptoms, which created a big challenge in diagnosis and treatment.Case presentation:A 53-year-old woman complained of hemiheadache, exophthalmos in the right eye, and limitation in lateral eye movements progressing to diplopia in the past 2 months. The physical examination of the rest systems was unremarkable. The radiological investigations revealed a hyperdense lesion arising from the right greater wing of the sphenoid bone and compressed on the orbit’s components and eye muscles, which caused proptosis. The radiological findings suggested osteoma and the tumor was excised by craniotomy. The patient gets rid of the symptoms and the follow-up for 6 months was uneventful.Clinical discussion:Even hemiheadache, exophthalmos, limitation in eye movements, and diplopia are unfamiliar findings in osteoma, they may be its manifestations. Also, MRI is used as a diagnostic method with computed tomography scan in intracranial osteoma. These cases are treated by craniotomy.Conclusions:Even though osteoma is a benign tumor, it may form in unusual locations and cause unexpected symptoms. So, it should be a differential diagnosis in skull bony tumors. Also, it should be treated when exists in sensitive places to avoid irreversible outcomes.