Intradiploic epidermoid cyst in frontal sinus causing diplopia: Case report and literature review

Background: Epidermoid cysts are benign tumors that arise from the ectopic inclusion of epithelial cells and represent between 0.2 and 1.8% of all intracranial tumors. Those tumors seldom present in the frontal region or involve the frontal sinus. We report a giant extradural intradiploic epidermoid cyst invading the frontal sinus followed by a literature review to analyses a general profile of these cases. Case Description: A 23-year-old female with an intense left parietal headache with eye pain, diplopia and a frontal mass in left hemiface. At the examination, the patient had proptosis, divergent strabismus and altered gaze movement on upwards and medial positions of her left eye, and hypoesthesia on her left hemiface. The CT study of this lesion showed an expansive formation on her left frontal sinus with calcified borders invading the ethmoidal cell and the orbital roof, leading to proptosis and an impaired superior rectus muscle function. After microsurgery for tumor resection and cranial reconstruction, the histopathological study revealed findings compatible with an epidermoid cyst. Conclusion: To our knowledge, there are no significant guidelines for the management of intradiploic epidermoid cysts. This study suggests that in the analyzed cases, a surgical approach with total tumor resection often showed good results with only one case of tumor recurrence.