Intracranial Masson's lesion following stereotactic radiosurgery for treatment of intracranial arteriovenous malformations - a case series.

OBJECTIVES Masson tumor or intravascular papillary endothelial cell proliferation was first described in 1923. Only a few cases of intracranial Masson tumor have been reported following stereotactic radiosurgery (SRS). We report a series of 6 cases, age range 28-56 years, with intracranial Masson tumor following SRS for treatment of an intracranial arteriovenous malformation (AVM). METHODS We performed a retrospective case note review, reviewed the imaging, SRS records, and neuropathology specimens following surgical excision. RESULTS In our series all patients received Leksell SRS with the periphery of the AVM receiving doses ranging from 22-25 Gy. The time lapse from SRS to a clear enhancing mass appearing on imaging ranged from 5-10 years. Four patients underwent craniotomy and excision of the enhancing lesion for persistent edema and an enlarging cyst resulting in a resolution of symptoms. CONCLUSIONS SRS is an effective treatment for obliteration of intracranial AVMs.