A tricky case of unilateral orbital inflammation: carotid cavernous fistula in Graves-Basedow disease.

To describe a rare clinical case of Carotid Cavernous Fistula (CCF) in Graves-Basedow disease (GBD). A 62-year-old female with history of GBD and inactive Graves' ophthalmopathy (GO) was admitted with progressive exophthalmos in her right eye (RE) and diagnosed with GO reactivation the previous month. On examination, dilated and tortuous conjunctival blood vessels, chemosis and exophthalmos were observed in the RE. There was an asymmetry in the intraocular pressures of 20 mmHg in the RE and 10 mmHg in the LE. Laboratory results showed normal thyroid function and positivity of some of the antibodies related to immune thyroid disorders. Neuroimaging showed an early and abnormal filling of the cavernous sinus (CS) and an enlarged superior ophthalmic vein. Consequently, the diagnosis of CCF was established. Interventional treatment was performed with good clinical outcome and no recurrence after 6 months of follow-up. CCFs are abnormal arteriovenous connections between the carotid arteries and CS. CCF picture can mimic the GO's manifestations. Thus, CCF should be considered in the differential diagnosis of GO, especially in unilateral, asymmetric, and atypical cases. We reported herein a case of CCF in a patient diagnosed with GBD, having a previous history of inactive GO, a diagnostic challenge, since the first presumed diagnosis in patients with GBD is always GO. To the best of our knowledge, there are only three previous reports in the medical literature in which the CCF was diagnosed in a GBD patient with a history of GO. : CCF = Carotid Cavernous Fistula, GBD = Graves-Basedow disease, GO = Graves' ophthalmopathy, CS = cavernous sinus, SOV = superior ophthalmic vein, ICA = internal carotid artery, IOP = intraocular pressure.