British Journal of Radiology (2008) 81, e20-e22
© 2008 British Institute of Radiology
doi: 10.1259/bjr/59191880
Spontaneous resolution of a colloid cyst of the third ventricle
G Annamalai, FRCR1,
K W Lindsay, FRCS2 and
J J Bhattacharya, FRCR1
Departments of 1 Neuroradiology and 2 Neurosurgery, Institute of Neurological Sciences, Glasgow, UK
Correspondence: Dr Ganesan Annamalai, Department of Medical Imaging, MG 183, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. E-mail: gannmalai{at}bigfoot.com
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Abstract
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We report a case of an asymptomatic colloid cyst of the third ventricle in a 35-year-old male, which on follow-up MRI at 15 months appears to have spontaneously resolved. To our knowledge, this is the first such case reported and supports the role of conservative management of small asymptomatic colloid cysts.
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Introduction
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Asymptomatic colloid cysts of the third ventricle found incidentally may be managed safely and conservatively with observation and serial neuroimaging [1]. We report a case of an incidental colloid cyst, which on follow-up imaging appears to have spontaneously resolved. To the best of our knowledge, this is the first such case reported.
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Case report
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A 35-year-old man was admitted following head injury sustained whilst under the influence of alcohol. He had fallen down a flight of stairs and had bleeding from his right ear and nostril. A CT scan of his brain did not demonstrate any intracranial haemorrhage but there was asymmetry of the lateral ventricles (with the right being larger), and an incidental small hyperdense lesion of the third ventricle was noted (Figure 1)
. He made a good recovery, was discharged and remained asymptomatic. MRI 4 months later confirmed the presence of a 5 mm rounded lesion, which was homogeneously hyperintense to brain on T1 weighted (Figure 2), and hypointense on T2 weighted, images. Signal characteristics were not typical of blood products, and there was no ventriculomegaly. The imaging findings were characteristic for a third ventricular colloid cyst. As the patient had no symptoms attributable to this colloid cyst and no evidence of cerebrospinal fluid pathway obstruction, he was managed conservatively. 15 months after the initial presentation, follow-up MRI revealed that the previously noted colloid cyst had disappeared. The patient then re-attended for high-resolution MRI at 18 months, which confirmed that the cyst was no longer visible and appeared to have completely resolved (Figure 3).
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Figure 2. AT1 weighted sagittal MR image at 4 months demonstrating the hyperintense colloid cyst (arrow).
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Discussion
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Third ventricular colloid cysts are rare benign lesions accounting for 0.5–1% of primary brain tumours. They are endodermally derived and are composed of ciliated and non-ciliated cuboidal or columnar epithelial cells interspersed with mucus-containing goblet cells [2]. As the patient ages, these cells secrete a gelatinous material, resulting in cyst formation and expansion. They are typically located in the anterior third ventricle, attached to its roof and between the columns of the fornix. The majority present in the third and fourth decades of life accompanied by headaches, but other presentations include vertigo, memory deficit, seizures and behavioural disturbance. Sudden neurological decline and sudden death from acute obstruction of the foramen of Monroe have been well documented, especially with cysts larger than 1 cm [3, 4]. About two-thirds of colloid cysts have higher attenuation than the brain on CT, and one-third are isodense. MRI signal characteristics are variable, but commonly are homogeneously hyperintense to brain on T1 weighting and hypointense on T2 weighting.
Symptomatic colloid cysts are treated, with good results, by microsurgical or endoscopic procedures. Genuinely asymptomatic small cysts can be treated conservatively. Pollock and Huston [1] reported one of 58 (2%) incidental colloid cysts becoming symptomatic in a mean follow-up period lasting longer than 6.5 years, and in only two of 34 patients (6%) was either cyst enlargement or progressive hydrocephalus demonstrated on follow-up neuroimaging. Therefore, they conclude that observation and serial neuroimaging is safe in asymptomatic patients.
Colloid cyst enlargement on follow-up imaging has been well documented [1, 4]; Kachhara et al. [5] reported a case of a colloid cyst that increased in density and decreased in size following a cerebrospinal fluid diversion procedure. Motoyama et al. [6] reported a case of spontaneous rupture and shrinkage of a presumed colloid cyst of the third ventricle, with the patient developing increasing hydrocephalus. The mechanism responsible for the apparent spontaneous resolution of the colloid cyst in our patient is unclear. Although one possibility may be cyst rupture, our patient remained asymptomatic without any evidence of hydrocephalus. In addition, no obvious remnants of the cyst were apparent on high-resolution MRI.
Our case of spontaneous resolution of an incidental colloid cyst further supports the role of conservative management for these small asymptomatic cysts.
Received for publication July 19, 2006.
Revision received September 14, 2006.
Accepted for publication October 16, 2006.
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References
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- Pollock BE, Huston J. Natural history of asymptomatic colloid cysts of the third ventricle. J Neurosurg 1999;91:364–9.[Medline]
- Ho KL, Garcia JH. Colloid cysts of the third ventricle: ultrastructural features are compatible with endodermal derivation. Acta Neuropathol 1992;83:605–12.[CrossRef][Medline]
- Aronica PA, Ahdab-Barmada M, Rozin L, Wecht CH. Sudden death in an adolescent boy due to a colloid cyst of the third ventricle. Am J Forensic Med Pathol 1998;19:119–22.[CrossRef][Medline]
- Mathiesen T, Grane P, Lindgren L, Lindquist C. Third ventricle colloid cysts: a consecutive 12-year series. J Neurosurg 1997;86:5–12.[Medline]
- Kachhara R, Das K, Nair S, Gupta AK. Changing characteristics of a colloid cyst of the third ventricle. Neuroradiology 1999;41:188–9.[CrossRef][Medline]
- Motoyama Y, Hashimoto H, Ishida Y, Iida J. Spontaneous rupture of a presumed colloid cyst of the third ventricle. Neurol Med Chir 2002;42:228–31.[CrossRef]
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Abstract
Introduction
