451. Pituitary Apoplexy as a Cause of False Positive Temporal Artery Halo Sign
Creators: name: Wan1, Yvonne Chang Yee
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Presentation of Case: </strong>A 75-year-old male with a background of type 2 diabetes mellitus, chronic kidney disease and MPO-ANCA positivity with no evidence of vasculitis, presented with a two-day history of left sided headache and retroorbital pain. Subsequently he developed tunnel vision in his left eye, then the right eye, along with diplopia. C-reactive protein (CRP) was 9mg/l (normal range 0-5) and erythrocyte sedimentation rate (ESR) was 52 mm/hr. He had no jaw claudication or other ischaemic symptoms. He reported 4lb of weight loss and decreased appetite, but no other constitutional symptoms. On examination, he had bitemporal hemianopia, left eye ptosis and mydriasis. Both temporal artery pulses were palpable, but the left temporal artery was tender on palpation. Urinalysis was positive for glucose and ketones with plasma glucose of 16.2 mmol/litre. <strong>Diagnostic Testing: </strong>Temporal artery Doppler ultrasound in clinic showed thickening of both temporal arteries (ie positive halo sign) and normal axillary arteries. However subsequent MRI of the head showed an anterior pituitary mass lesion with suprasellar extension and intralesional haemorrhage, compressing the optic chiasm. <strong>Differential &amp; Final Diagnosis: </strong>Initial differential diagnosis included giant cell arteritis with atypical presentation, apparently confirmed by the positive halo sign on temporal artery ultrasound. Bitemporal hemianopia with CNIII palsy suggested a lesion of the optic chiasm with possible involvement of the left cavernous sinus. The final diagnosis following MRI was of pituitary apoplexy, histologically confirmed as a gonadotrophinoma. <strong>Discussion of Management: </strong>The patient was admitted for management of his hyperglycaemia with ketosis. In view of the acute visual field defect, he was initially treated with high dose glucocorticosteroids for presumed giant cell arteritis while undergoing further diagnostic evaluation. Immunosuppression was discontinued once the pituitary mass was discovered. He underwent transphenoidal resection of the pituitary mass and his headache and diplopia resolved with some improvement of his visual fields. <strong>Conclusions: </strong>Vascular ultrasound has been proven a valuable diagnostic test in the evaluation of suspected giant cell arteritis with a specificity of 95% in a recent meta-analysis (Sebastian 2021), although the possibility of a false positive result remains. We are not aware of any previous reports of pituitary apoplexy causing a positive halo sign on temporal artery ultrasound, which we presume in this instance to be a manifestation of increased cavernous sinus pressure. While the combination of headache, acute visual field defect, diplopia and mildly raised inflammatory markers may raise the strong suspicion of giant cell arteritis, careful evaluation is required to anatomically locate the pathology causing the given ocular involvement, in case a more likely alternative diagnosis becomes apparent. <strong>Disclosures </strong>None