Inflammatory Pseudo-tumour Orbitae (PTO): An Atypical Manifestation of Giant Cell Arteritis (GCA)

Intraorbital findings in giant cell arteritis on black blood MRI

OBJECTIVE

Blindness is a feared complication of giant cell arteritis (GCA). However, the spectrum of pathologic orbital imaging findings on magnetic resonance imaging (MRI) in GCA is not well understood. In this study, we assess inflammatory changes of intraorbital structures on black blood MRI (BB-MRI) in patients with GCA compared to age-matched controls.

METHODS

In this multicenter case-control study, 106 subjects underwent BB-MRI. Fifty-six patients with clinically or histologically diagnosed GCA and 50 age-matched controls without clinical or laboratory evidence of vasculitis were included. All individuals were imaged on a 3-T MR scanner with a post-contrast compressed-sensing (CS) T1-weighted sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) BB-MRI sequence. Imaging results were correlated with available clinical symptoms.

RESULTS

Eighteen of 56 GCA patients (32%) showed inflammatory changes of at least one of the intraorbital structures. The most common finding was enhancement of at least one of the optic nerve sheaths (N = 13, 72%). Vessel wall enhancement of the ophthalmic artery was unilateral in 8 and bilateral in 3 patients. Enhancement of the optic nerve was observed in one patient. There was no significant correlation between imaging features of inflammation and clinically reported orbital symptoms (p = 0.10). None of the age-matched control patients showed any inflammatory changes of intraorbital structures.

CONCLUSIONS

BB-MRI revealed inflammatory findings in the orbits in up to 32% of patients with GCA. Optic nerve sheath enhancement was the most common intraorbital inflammatory change on BB-MRI. MRI findings were independent of clinically reported orbital symptoms.

KEY POINTS

• Up to 32% of GCA patients shows signs of inflammation of intraorbital structures on BB-MRI. • Enhancement of the optic nerve sheath is the most common intraorbital finding in GCA patients on BB-MRI. • Features of inflammation of intraorbital structures are independent of clinically reported symptoms.

Magnetic resonance imaging findings in giant cell arteritis

PurposeGiant cell arteritis (GCA) is a systemic vasculitis that affects medium-to-large-caliber arteries. Early diagnosis and treatment is essential as involvement of the ophthalmic artery or its branches may cause blindness. Radiographic findings may be variable and non-specific leading to delay in diagnosis. We conducted a review of the literature on neuroimaging findings in GCA and present a retrospective case series from tertiary-care ophthalmic referral centers of three patients with significant neuroimaging findings in biopsy-proven GCA.MethodsRetrospective case series of biopsy-proven GCA cases with neuroimaging findings at the Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital between 2010-2015 were included in this study. Literature search was conducted using Google Scholar and Medline search engines between the years 1970 and 2015.ResultsWe report findings of optic nerve enhancement, optic nerve sheath enhancement, and the first description in the English-language ophthalmic literature, to our knowledge, of chiasmal enhancement in biopsy-proven GCA. We describe four main categories of neuroimaging findings that may be seen in GCA from our series and from past cases in the literature.DiscussionIt is essential that clinicians be aware of the possible radiographic findings in GCA. Appropriate and prompt treatment should not be delayed based upon these findings.