Symptomatic colloid cyst

Clinical History

A 56-years-old man consulted his General Practitioner with a history of increased feeling of cranial pressure and headache for two days. The patient was sent to the local Casualty Department. In clinical examination nothing abnormal was detected. All laboratory tests were normal. A cranial CT was performed, followed by cranial MRI.

Imaging Findings

On admission a plain cranial CT was performed. This revealed a 4 x 6 mm hyperdense lobulated lesion within the ventral part of the third ventricle. One lobulated part of the lesion developed downwards into the central part of the third ventricle. Another part of the lesion protruded into the left ventricle through the foramen of Monro. The ventricles were symmetrical with a normal width. There were no other lesions and there was no sign of intracranial bleeding or ischaemia (Fig.1.).
The subsequently performed MRI confirmed the lesion within the third ventricle. The lesion was isointense in T1-w imaging and hyperintense in FLAIR and T2-w. No contrast enhancement of the lesion was seen. There was no midline shift. The ventricles show a normal width. The rest of the neurocranium showed a normal MRI anatomy (Fig 2: FLAIR axial, Fig 3: T2-w coronal, Fig 4: T1-w axial plain, Fig 5: T1-w after contrast (7 ml Gadovist).

Discussion

Colloid cyst is a benign lesion that develops within the anterior aspect of the third ventricle adjacent to the foramen of Monro [2]. It is the most common lesion in this region [3]. Usually colloid cysts are round-shaped or ovoid [4].The lesion found in this patient showed the CT characteristics of a colloid cyst regarding density and localisation. MRI findings differ with T1-w imaging varying from hyperintense to isointense [1]. In our patient the lesions was almost isointense compared to the normal brain. There can be signs of intermittent or persistent hydrocephalus caused by the obstruction of the foramen of Monro. In our case, there was - at the point of examination - no sign of hydrocephalus, the ventricles showed a normal width. Cases of sudden death can be explained by the non-recognition of symptoms especially if they are mild and non-specific [5]. The size of a colloid cyst can range from 3 – 40 mm but size may not be a reliable predictor of outcome as even small cysts can cause sudden death [6].
The usual presentation of colloid cyst are headaches. The headache is intermittent and is decreased on lying down, which is unusual for a headache due to an intracranial space-occupying lesion [5]. Other symptoms can be vertigo, memory deficit and diplopia [5]. As there were no other signs of a space-occupying lesion and no other imaging findings of a subarachnoidal haemorrhage or cardiovascular abnormalities the symptoms of our patient were contributed to the colloid cyst in view of the MR-characteristics and the position of the lesion within the III. ventricle near the foramen of Monro. Although spontaneous remission of colloid cysts are described [7] and colloid cysts are benign lesions with generally good prognosis and most cases remain asymptomatic [8], a neurosurgical referral should be recommended. Surgical treatment of colloid cysts comprises different possible techniques: Stereotacic aspiration, endoscopic fenestration and microsurgical approach [9].
Our patient showed the unusual presentation of a very lobulated shape with a protrusion into the third ventricle downwards and through the left foramen of Monro. Our patient was referred to the neurosurgeon as sudden death due to ventricular obstruction of the foramen of Monro leading to acute hydrocephalus is possible [8] and he already showed a protrusion of the tumour through the left foramen of Monro. He was treated successfully by neurosurgical approach and removal of the cyst.

Differential Diagnosis List

Final Diagnosis

Colloid cyst

URL:	https://www.eurorad.org/case/13336
DOI:	10.1594/EURORAD/CASE.13336
ISSN:	1563-4086