Selective retinal arterial whitening in retinal astrocytic hamartoma in tuberous sclerosis.

This case report aims to describe and understand the mechanism behind the selective retinal arterial whitening in a case of retinal astrocytic hamartoma (RAH) associated with tuberous sclerosis complex (TSC). Multimodal imaging of a late-adolescent female with TSC-associated RAH demonstrated unique vascular features including selective whitening of the retinal arteries with sparing of the retinal veins. Genetic testing confirmed a TSC2 (tuberin) gene mutation, known to affect the mammalian target of rapamycin (mTOR) signalling pathway. To understand the mechanism behind selective arterial involvement, a literature review was conducted on vascular alterations in other TSC-affected organs (skin and kidneys). Histopathological analyses suggest that defects in the mTOR signalling pathway affect smooth muscle cells. Unlike retinal veins and smaller retinal arterioles, larger retinal arteries possess smooth muscle cells, making them more susceptible to similar pathological changes. Selective whitening of retinal arteries in TSC-associated RAH likely results from vascular remodelling influenced by mTOR mutations, leading to alterations in smooth muscle cells.