Orbital involvement by Wegener's granulomatosis: imaging findings

The purpose of this study was to define patterns of Wegener's granulomatosis (WG) orbital disease involvement.

We evaluated the orbital examinations of 14 WG patients (CT for nine, MR imaging for three, and both CT and MR imaging for two) for the number of involved orbits, intraconal or extraconal location, involvement of the orbital apex, sinus involvement, bony erosion, and optic nerve compression. MR images were analyzed for signal characteristics and enhancement patterns.

We found orbital disease to be unilateral in 12 patients (86%) and bilateral in two patients (14%) (total of 16 orbits). In 11 orbits (69%), coexistent orbital and sinus diseases with bony erosion were present. Orbital disease without sinus disease was seen in five orbits (31%). Intraorbital disease distribution was as follows: solely extraconal--seven orbits (44%) (four with involvement of muscle); intraconal with muscular involvement--one orbit (6%); combined intra- and extraconal--seven orbits (44%); and primarily orbital apex--one orbit (6%). Involvement of the apex was seen in six orbits. The WG mass was hypointense relative to orbital fat on three standard T2-weighted MR images. We saw homogeneous MR contrast enhancement in all four orbits studied on enhanced T1-weighted images.

Intraorbital WG involvement is usually accompanied by paranasal sinus disease. A hypointense signal on T2-weighted MR images is helpful in suggesting the diagnosis.