18 year old woman presented to ER with three day history of headache. Ten pound weight loss over past 6 months.
â€¢ Large suprasellar CSF lesion (arachnoid cyst)
â€¢ Invaginating into the third ventricle and left lateral ventricle
â€¢ No pathologic enhancement noted
â€¢ Epidermoid cyst
â€¢ Rathke cleft cyst
â€¢ Arachnoid cyst
â€¢ Diverticula of membrane of Lilequist
Dx: Arachnoid Cyst with extension through Third ventricle into lateral ventricle
Dx Confirmed by: MRI and Surgery
Intraventricular portion of cyst was fenestrated with a surgical endoscope.
True cysts of the CNS are named by their lining. Arachnoid cysts - sometimes called "intra-arachnoid cysts" - are fluid filled spaces (containing CSF). They may be congenital or acquired. The most common location is in the middle cranial fossa.
So-called "secondary" or "acquired" arachnoid cysts may develop in relation to slowly growing extraaxial neoplasms, like meningioma and Schwannoma.
Arachnoid cysts are common and many if not most are discovered as asymptomatic incidental findings. A large study of almost 12,000 children (under nineteen) found a prevalence of 2.6% (309/11,738 pts.). They were more common in boys.
A subset of 111 were followed for a mean of 3.5 years:
11/111 increased in size (all these pts. < 4 yrs old)
87/111 did not change
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