11. A Case of Amyloid Angiopathy Mimicking Giant Cell Arteritis

Abstract

Background: An 87-year-old lady was seen in eye casualty with sudden loss of vision in her left eye. Fundoscopy revealed a pale, blurred optic disc and retinal haemorrhages consistent with anterior ischaemic ocular neuropathy. With an elevated ESR of 108 mm/h and CRP of 65 mg/l a diagnosis of GCA was made. Methods: Initial laboratory tests were also notable for a Hb of 8.4 g/dl and chronic renal failure with a creatinine of 199 mmol/l. Following a left temporal artery biopsy she was given i.v. methylprednisolone 500mg and commenced on 60mg prednisolone. Later that evening the patient deteriorated with a NSTEMI, cardiac failure, sepsis from bronchopneumonia and worsening renal function. She improved clinically with supportive treatment, i.v. antibiotics and another 500mg i.v. methylprednisolone. Within 1 week her CRP and ESR dropped to 15 mg/l and 30 mm/h respectively. Results: Whilst convalescing on the ward, the temporal artery biopsy histology became available. Pink eosinophilic material on haematoxylin and eosin staining and a giant cell was seen. Elastic Van Geison stain demonstrated a disrupted internal elastic lamina. However, congo red staining revealed amyloid deposition with apple-green birefringence under polarized light. Due to the histological features seen a rheumatological opinion was sought. Further history was elucidated. Myeloma was diagnosed 4 years previously and she had been treated with 5mg prednisolone. There had been difficulties with neutropenia on chemotherapy. Although there was no headache, there was a definitive history of jaw claudication and additional examination revealed a woody, thickened right temporal artery. Following discussion with haematology, ophthalmology and a review of the histology, it was felt that the biopsy could be entirely explained by amyloid angiopathy. Therefore the patient was diagnosed with systemic amyloidosis, presumed AL type, with vascular, cardiac and renal involvement. The dose of prednisolone was tapered to her baseline dose over 3 months with no symptom recurrence. Treatment of her myeloma remained palliative. She did not have any return of vision in her left eye. Conclusion: AL amyloid deposits in temporal arteries have been observed for more than 50 years and can cause diagnostic confusion with GCA. AL amyloidosis has been reported as presenting with GCA like vascular symptoms such as jaw claudication and can occur before the diagnosis of myeloma. They can have a comparable inflammatory response to corticosteroids. Histological confusion occurs as both may have an eosinophilic infiltrate, a disrupted internal elastic lamina and giant cells. It is important to be aware of amyloidosis as a differential diagnosis in patients with clinical symptoms of GCA. This has consequences on management of the disease, as chemotherapy, rather than corticosteroid, is the mainstay of therapy.