P029 Ocular syphilis: a mimicker for giant cell arteritis
Authors: Ali Sabreen , Lekh Sophia , Tench Colin 
Published: April 2023

Abstract

Background/Aims
Syphilis has seen a resurgence in the United Kingdom in recent years. It is a sexually transmitted disease caused by Treponema pallidum spirochaete infection, and typically presents as painless genital ulceration in its primary stage; left untreated it can progress rapidly to secondary and tertiary stages with multi-system involvement and wide-ranging symptoms, hence it being labelled ‘the great imitator’. We report a case of a patient presenting with classical features of giant cell arteritis (GCA), ultimately being diagnosed with neuro-ocular syphilis.

Methods
A 65-year-old man with a background of hypertension and migraines presented to our hospital with a 3-week history of temporal headache, scalp tenderness and jaw ache. He described lethargy, weakness and weight loss. On examination he had a prominent left temporal artery, with concurrent scalp tenderness; neurological and general medical examination were otherwise normal. Blood tests showed an erythrocyte sedimentation rate (ESR) of 66 and a C-reactive protein (CRP) of 115, leading to a strong clinical suspicion of GCA. He was commenced on 60mg of oral prednisolone with immediate improvement of his symptoms at this dose. Subsequent temporal artery ultrasound and temporal artery biopsy were negative for GCA. On tapering his steroids to 40mg he experienced partial relapse of his symptoms. Following Neurology review his steroid taper was adjusted to decrease more slowly. On 20mg of prednisolone the patient began experiencing stabbing retro-orbital pain and visual blurring, and was assessed by Ophthalmology with no local cause for his symptoms identified - he was therefore pulsed with intravenous methylprednisolone for a flare of GCA. Despite an initial response, the patient continued to experience intermittent symptoms on steroids; imaging with PET-CT did not show evidence of inflammation or malignancy and an MRI of his brain and orbits was normal.

Results
The patient eventually re-presented to Ophthalmology with floaters, pain and decreased vision and a spot diagnosis of posterior placoid chorioretinitis was made after retinal examination. Characteristic yellowish ovoid lesions confluent in the macular area were noted, as well as ellipsoid zone loss with nodular retinal pigment epithelium on optical coherence tomography (OCT) imaging. This condition is pathognomonic of neuro-ocular syphilis and serological testing confirmed the diagnosis, with a high rapid plasma reagin (RPR) titre of 1:512. He was treated with a course of intramuscular Ceftriaxone with a rapid resolution of his symptoms, and was successfully weaned off all steroid therapy.

Conclusion
Diagnosing GCA remains a clinical challenge for rheumatologists, especially in cases with typical symptoms and signs but negative confirmatory testing on imaging and histology. There are a wide range of conditions that resemble GCA, and neuro-ocular syphilis is one such diagnosis that has been reported in the literature as a mimic, as demonstrated by this important case.
Disclosure
S. Ali: None. S. Lekh: None. C. Tench: None.