A 25 y.o. female resident had a seizure in the call room. She has no history of seizures and complains only of flank pain after her recovery.
What do you notice on her abdominal CT? Could that lead you to a diagnosis?
Our patient had an angiomyolipoma which is strongly associated with tuberous sclerosis. Angiomyolipomas are benign tumors containing blood vessels, muscle and fat and are considered hamartomas. 70-80% of individuals with tuberous sclerosis develop these benign tumors.
Tuberous sclerosis was the cause of our patient’s seizure. In the brain several types of hamartomas form; giant cell astrocytomas, cortical tubers and subependymal nodules. the subependymal nodules have an unusual triagular shape with the apex near the ventricles. An estimated 90% of individuals with the disease develop neuropsychiatric disorders (seizures, autism, anxiety, and depression)
subependymal lesions on MRI
It is an autosomal dominant disorder with characteristic hamartomas in multiple organs. It is often the result of mutation in the TSC1 and TSC2 genes however 1 in 4 individuals does not have a known mutation. TSC1 and TSC2 are both tumor suppressor genes that function according to Knudson’s “two hit” hypothesis. A second mutation must occur in the second allele before a tumor can develop. This explains why despite its high penetrance tuberous sclerosis has widely variable expression. The disease has a variable course with some patients having no findings or only some of the characteristic clinical findings.
angiofibromas in tuberous sclerosis
Clinically, the most common findings on exam are:
SKIN: shagreen patches, angiofibromas, hypopigmented macules (ash spots)
NEURO: seizures, subependymal brain hamarto mas seen on MRI
RENAL: angiomyolipomas on CT, often presenting as flank pain
Many more regions of the body can be involved
Our patient was able to finish her residency and was maintained on seizure medication.
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