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.