Retinal microangiopathy as an initial manifestation of familial amyloid cardiomyopathy associated with transthyretin e89k mutation.

Abstract

To report a rare case of transthyretin (TTR) familial amyloid cardiomyopathy with retinal microangiopathy and vitreous amyloid as the initial manifestation. A 54-year-old woman presented with bilateral retinal microangiopathy, presumed idiopathic retinal vasculitis. She subsequently developed retinal ischemia associated vitreous hemorrhage and was treated with panretinal laser photocoagulation. Clinical eye signs remained stable for 6 years with the absence of overt inflammation. However, the patient developed chest pain and atrial flutter and underwent echocardiography, cardiac magnetic resonance imaging, and Tc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scintigraphy to investigate possible cardiac amyloidosis. Sequencing of the TTR gene was conducted and a rectal biopsy performed for tissue diagnosis. A full neurologic screen was also conducted. Cardiac investigations were highly suggestive of an amyloid cardiomyopathy. The rectal biopsy stained positive for Congo red with demonstration of apple green birefringence, confirming amyloid, and immunostaining confirmed the TTR subtype. Gene sequencing revealed heterozygous TTR mutation encoding E89K variant. No significant neuropathy could be detected. Amyloid should be considered as a masquerade diagnosis in cases of retinal microangiopathy, especially in the absence of inflammation. Liaising with physicians for systemic evaluation and TTR gene sequencing is essential for early diagnosis and management of this rare condition.