This submission is a 23 year old male patient who became lethargic and somnolent after playing soccer. On physical exam he was somnolent, but arousable with no focal neurologic deficits. An unenhanced CT of the brain initially demonstrated right frontal horn dilatation. A subsequent CT demonstrated bilateral lateral and third ventricular dilatation. Following placement of a ventriculostomy catheter, MRI was obtained and demonstrated a cystic-appearing third ventricular lesion. The lesion was hyperintense on T1WI (Fig 1) and hypointense on T2WI (Fig 2).
During attempted endocscopic removal of the lesion, it was “lost” from the surgical forceps, though a partial specimen was retrieved. Subsequent MR imaging demonstrated that the cyst was now located in the ventricular trigone (Fig 3). At pathology, findings were consistent with a cysticercal cyst. There was no scolex in the specimen.
Interestingly, review of the preoperative CT studies suggested that the cyst had started in the right frontal horn (Fig 4) and also revealed a parenchymal calcification (Fig 5), almost certainly an additional manifestation of cysticercosis in this Hispanic patient. Key “hints” to correct identification of this Aunt Mickey case included the parenchymal calcification, cyst mobility, and ethnicity of the patient.
Colloid cysts are the most common lesion of the anterior superior third ventricle. They are of variable signal intensity on T1 and T2 weighted images, presumably reflecting the variable viscosity of proteinaceous cyst contents. Cysts may be CSF-like (dark on T1 and bright on T2), or when more proteinaceous, may appear bright on T1 and dark on T2 weighted images. The occasional similarity of racemose cysts of cysticerosis to colloid cysts has been previously reported. Migration of the cyst has also been reported.
References:
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2: Wray SD, Ellis TL, Bianco S. Migratory neurocysticercosis mimicking a third ventricular colloid cyst. Case report. J Neurosurg. 2001 Jul;95(1):122-3.
3: Couldwell WT, Chandrasoma P, Apuzzo ML, Zee CS. Third ventricular cysticercal cyst mimicking a colloid cyst: case report. Neurosurgery. 1995 Dec;37(6):1200-3.
4: do Amaral LL, Ferreira RM, da Rocha AJ, Ferreira NP. Neurocysticercosis:Evaluation with advanced magnetic resonance techniques and atypical forms. Top Magn Reson Imaging. 2005 Apr;16(2):127-44.
5: Garcia HH, Del Brutto OH; Cysticercosis Working Group in Peru. Neurocysticercosis: updated concepts about an old disease. Lancet Neurol. 2005 Oct;4(10):653-61.
6: Castillo M. Imaging of neurocysticercosis. Semin Roentgenol. 2004 Oct;39(4):465-73.
