How do patients with tuberous sclerosis typically present?
Typically presents in childhood with the classic triad of : 1) seizures : absent in 1/4 of individuals, 2) mental retardation : up to half of affected individuals have normal intelligence, and 3) adenoma sebaceum : present in ~75% of patients.
What imaging features are useful in differentiating subependymal giant cell astrocytomas from the more common subependymal hamartomas?
The single best feature is demonstrating growth. Having said that finding a large mass such as this implies growth and is highly suggestive of the diagnosis in a patient with tuberous sclerosis especially when located at the foramen of Munro and associated with acute hydrocephalus (another marker of growth). Enhancement is also suggestive although hamartomas can also sometimes enhance.
Subependymal nodule seen to be calcified on CT is visible (red arrow) on FLAIR and T2 as a region of low signal.
Best seen on FLAIR are radial glial bands (yellow arrows) and cortical / subcortical tubers (green arrows).