Radiation-Induced Meningioma of the Orbit: Natural History, Potential for Malignant Transformation, and Surgical Management

Radiation-induced meningiomas are an increasingly recognized entity known for aggressive clinical behavior and high recurrence rates. The primary treatment modality is complete resection of the tumor including all involved dura and bone. Meningiomas of the medial sphenoid wing with extension into the orbit are particularly challenging surgical lesions, and obtaining a Simpson grade 1 resection is generally not possible in these cases.

This report describes a patient with a radiation-induced atypical meningioma of the medial sphenoid wing and orbital apex that recurred despite multiple Simpson grade 3 resections. Progressive anaplastic transformation and extension into the orbit resulted in complete loss of useful vision with a frozen, proptotic globe. A radical resection of the recurrent tumor, involved dura, and bone with exenteration of the orbit and reconstruction with a myocutaneous flap was performed. Postoperatively, he made an excellent recovery and was discharged on day 6. The final pathology was atypical meningioma with anaplastic features (WHO grade II-III).

In light of this case, we discuss the natural history, histopathology, and potential for malignant transformation of atypical, radiation-induced meningiomas. Further, we discuss surgical management of atypical meningiomas that occupy the cranioorbital compartment. Finally, we discuss the surgical options and rationale for orbital exenteration and cranial reconstruction in these cases.