The patient came to the clinic with her mother 20-February-2016. The mother telling that she noticed that the patient is bending her head to the right shoulder from the first month of age for what MRI of the brain done 08-September-2015, which showed huge cystic mass in the quadrigeminal cistern with massive supra and infratentorial growth with secondary hydrocephalus. The cystic mass fulfilling the third ventricle and pushing down the cerebellum. The H/C was 44 cm and the fontanel was lax 2x1 cm. The first visit was without the child in 15-November-2015. It was advised at that time to wait and see to progression of the mass. The second visit without the child was 14-February-2016 with new MRI performed 26-January-2016 showing enlargement of the mass 150% in comparison to the first with more pronounced hydrocephalus. The family was told to bring the child for surgical intervention. The patient born full term with Caesarian section.

On examination: the patient has tendency to bend the head to the right shoulder without presence. There is slight paresis left VI nerve with slight left sided hemiparesis. The H/C now is 47 cm and the fontanel is lax 1x1 cm with no proper signs of increased ICP.

The patient was sent for detailed MRI of the brain with contrast with MRA of the brain, SWI and spectroscopy. Spectroscopy ruled out the presence of malignancy. The mass now is pressing down the mesencephalo-pontine structures.

The patient in supine position with interhemispheric approach right side in the posterior SSS projection. The cystic mass was projecting posterior to the splenium. Spinal needle was used with gradual evacuation of the cyst fluid, which proved to be CSF consistency. The fluid and the dissected and bisected wall were sent to all laboratory and histologic verification. All the running veins were preserved. The floor of the cyst was also perforated and bisected to provide wide communication with the third ventricle. The layers adherent to the brainstem and the thalami were left intact. Strict hemostasis with water-tight closure of the dura. Routine closure of the wound. MRI of the brain was performed and showing practical resection of the mass with remnants at the deep cerebral veins and and vein of Galen. The patient was extubated and regained normal activity. 10 min after recovery, she progressed respiratory arrest, for what she was intubated and sent another time for new MRI, which proved to be identical with the last one. The patient then regained full recovery and extubated and sent to the ICU for strict observation.

The patient in the next day was fully alert and neurologically free and the final histologic result was colloid cyst.

The patient has progressing cystic mass with progressing hydrocephalus. Surgical intervention is the only solution.

Using stereotactic devices with such soft cranium is inadequate.

The patient progressed respiratory arrest due to rapid decompression of the brainstem. Despite the fact, that decompression was performed slowly over 30 min, but the brainstem cannot some times tolerated such decompression and can show such functional reactions in the immediate postoperative period.