ABSTRACT
BACKGROUND: Osteomas of the paranasal sinuses are benign, slow-growing bone tumors that can cause a variety of clinical features depending on their size and location. Most osteomas are asymptomatic and located in the frontal sinus. In rare cases, they may grow to extend into the cranial or orbital cavities, resulting in atypical presentations. The authors presented an aggressive case of a frontoethmoidal sinus osteoma with intracranial extension of an inflammatory sinonasal polyp. OBSERVATIONS: A 30-year-old man with a history of chronic sinusitis presented to the hospital after three episodes of loss of consciousness, chronic worsening of headache, and decreased sense of smell. Rhinoscopic examination showed mucosal polyps arising from the infundibulum and the superior meatus. Computed tomography showed a fibro-osseous mass in the left frontal sinus. Subsequent brain magnetic resonance imaging with and without contrast revealed a large, septated intracranial left frontal lesion approximately 6.5 cm in diameter that was compressing the underlying brain parenchyma. LESSONS: Intracranial extension of frontal sinus osteomas can have dire neurological implications. Early detection of lesions obstructing the paranasal sinuses outlet could prevent intracranial extension of the disease. The surgical approach to such tumors may be endonasal, open cranial, or a combination of both.
