Nonarteritic anterior ischemic optic neuropathy associated with acute glaucoma secondary to Posner-Schlossman syndrome.

histochemical comparisonof thevascular growth factors and hormonal markers in angiomatous and atypical meningiomasaswellashemangiopericytomas.Theydemonstratedevidence ofhormonal receptors toactinonly in angiomatous meningiomas, and to muscleactinonly inhemangiopericytomas.Inaddition,theyshowedacompleteabsenceofVEGF-1intheextravasatesobtained fromhemangiopericytomas.Thiscasefurthervalidatestheir findingsbydemonstratingthepresence of VEGF-1 and VEGF-2 as well as vimentin inthespecimen.Therefore, in theabsenceofclearmorphologicaldifferences, in certain cases the clinical distinction between vascular tumors andhighlyvascularizedmeningiomas can be difficult; one may need to rely on histochemical analysis. This case is unique because primaryorbitalmeningiomasnotarising from the optic nerve are exceedingly rare. Although somewhat controversial, it isbelievedthatasubpopulation of orbital meningiomata arises from withintheorbital tissues,unrelatedto thewallsortheopticnerve.Inareview ofseveralcasesoffree-lyingorbitalmeningiomata, McMichael and Cullen proposed various possibilities as the originof these tumors: (1) that the tumor isoriginally attached to theoptic sheathbut latermigratesawayfromit; (2) that the tumorcells arise fromthe orbital interstitial tissues; (3) that the tumorcellsarisefromsuturesbetween orbital bones that contain herniated meninges; or (4) that the cells originatefromtheduramater liningtheorbit.Becauseof theirpeculiarbehavior and location, these orbital meningiomas are often misdiagnosed as hemangiomas or dermoid cysts. In an attempt to find other diagnostic differentiating clues, Uttley at al reviewed several cases of intracranial atypical meningiomas as compared with hemangiopericytomas. They discovered that on angiography, hemangiopericytomas in particular demonstrated a major vascular supply from the branches of the internal carotid or vertebral artery. However, they were unable to show clear differences on magnetic resonance imaging or computed tomography. Therefore, it is doubtful that radiologic clues alone can truly aid in the diagnosis of this condition. This case is especially unique in that the histologic examination showed areas completely devoid of tumor and an uninvolved optic nerve sheath. On further review, the histologic findings are consistent with a primary angiomatous meningioma of the orbit, a previously unreported entity. We conclude that in cases of atypical behavior of an otherwise classic vascular tumor of the orbit, one should consider the possibility of an angiomatous meningioma.