60-year-old female:
– Since a few weeks eye movement disorder and diplopia of the left eye, tinnitus, and sinusitis.
– Non-enhanced CT of the orbits is performed (due to contrast allergy).
What are your findings?
Widened infraorbital canal left eye with thickening of the infraorbital nerve.
What is your differential diagnosis and do you want more imaging?
Yes, we want MRI to sort things out more.
Findings: Smoothly thickened T2 hyperintense, enhancing infraorbital nerve in its canal. No continuation posteriorly to the vidian canal or anteriorly to the pre-antral region. No pathologic paranasal sinus mass or pharyngeal mucosal mass indicating perineural tumor spread.
Differential diagnosis:
Schwannoma.
Less likely malignant cause like perineural tumour spread.
Biopsy is performed of right lacrimal gland, since clinically this was found to be prominent (radiologically slight asymmetry, slightly higher T2 signal).
Histopathology: IgG4 disease or dacryoadenitis.
After this, whole body scanning showed evidence of IgG4 disease in the pancreas also. Patient was treated with steroids.
Follow-up MRI: Decrease in size of the infraorbital nerve from 11 to 5 mm. Still high T2 signal, however, the decrease in size on steroids suggests other diagnosis than schwannoma, in this case probably involved in orbital IgG4 disease. Rare!
