An unusual location and presentation of a usual pathology-Colloid cyst of fourth ventricle presenting as spontaneous rhinorrhea.

Colloid cysts are relatively rare benign intracranial lesions preferentially located within the third ventricle. There are only a few reports in which they have been found to be ectopic, such as in the fourth ventricle. A young female presented on with spontaneous non-traumatic cerebrospinal fluid (CSF) rhinorrhoea for three months which was positional in nature, relieved temporarily by neck flexion. Magnetic resonance imaging (MRI) scan showed a focal well-defined rounded cystic lesion along the fourth ventricle, showing subtle peripheral rim enhancement. Significant hydrocephalus was also noted. A suboccipital craniotomy and total excision of the lesion was done. Postoperatively, the patient recovered quickly with no neurological deficits. Her rhinorrhoea was completely cured. Histopathology was consistent with a colloid cyst. Colloid cyst is rarely found in infratentorial location. However, such a rare diagnosis has to be considered in the differential diagnosis in patients who present with an infratentorial cystic lesion associated with spontaneous CSF rhinorrhoea.