[1526] Pathological Review of 50 Intraorbital Meningiomas Using WHO 2007 Criteria

D Jain, CG Eberhart. Johns Hopkins Medical Institutions, Baltimore, MD

Background: Meningiomas represent 2 to 4% of all intraorbital tumors. In clinical series, they are approximately equally divided between those arising from the optic nerve, and those extending into the orbit from adjacent structures, usually the sphenoid wing. Although the grading and subclassification of intracranial meningiomas has been relatively well studied, no large series of intraorbital meningioma has been reported using the grading scheme introduced by the WHO in 2000. Herein, we describe the histopathologic features and WHO grades of 50 intraorbital meningiomas.
Design: Intraorbital meningiomas diagnosed between 1968 and 2008 were retrieved from the archives of the Neuropathology and Eye Pathology Laboratories at our institution. Clinical data were also retrieved from the hospital archives, including patient age, sex, and intraorbital location of the tumor. Hematoxylin and eosin stained slides from all cases were reviewed according to the WHO 2007 classification scheme.
Results: A total of 50 intraorbital meningiomas were reviewed. The mean age at presentation was 45 years (range, 8 to 96 years), and four tumors arose in children, ages 8 to 15 years. Two patients were known to have neurofibromatosis type 2 (NF2). Intraorbital meningiomas were more frequently encountered in females (30 cases) than in males (20 cases). In 21 patients (13 females, 8 males), the tumor was associated with the optic nerve. In the remaining 29, the optic nerve was not known to be involved. The most common histopathologic subtype (28/50 tumors, 56%) was meningothelial. An additional 20 tumors (40%) were classified as transitional, and 2 (4%) were predominantly angiomatous. Focal microcystic change was present in 2 tumors. Most of the tumors (46/50, 92%) were WHO grade I, with less than 4 mitotic figures per 10 high power fields (hpf). Four tumors (8%) were WHO grade II (2 males and 2 females), with more than 4 mitotic figures per 10 hpf. One of these grade II tumor also exhibited brain invasion, and a second showed optic nerve invasion. Invasion of either dura, bone, muscle, orbital fat, lacrimal gland, choroid or sclera was observed in 19 cases.
Conclusions: In our series, intraorbital meningiomas were most frequently of the meningothelial or transitional subtypes, and WHO grade I. One relatively common intracranial subtype, fibrous meningioma, was not encountered. The percentage of WHO grade II tumors in the orbit (8%) is similar to that reported for intracranial tumors using the current grading scheme.
Category: Ophthalmic

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 211, Tuesday Morning