Choroid plexus cyst of the left lateral ventricle with intermittent blockage of the foramen of Monro, and initial invagination into the III ventriclein a child

A cyst of the choroid plexus of the left lateral ventricle with intermitten t blockage of the foramen of Monro and initially with invagination of the I II ventricle in a child is described. In a 6-week-old boy a ventriculoatria l shunt was implanted for correction of an active asymmetrical hydrocephalu s of unknown origin. When he was 3 months of age a water-soluble contrast C T ventriculography revealed a noncolloid cyst localised predominantly in th e upper portion of the III ventricle. At that time the ventricular catheter obstructed with choroid plexus was removed; new bilateral catheters in a p arieto-occipital region were implanted. In the course of the next 4 years, first the atrial catheter had to be extracted and then the peritoneal cathe ter was changed, in both cases because of obstruction. Periods of normal li fe alternated with periods of transient and intermittent symptoms of increa sed intracranial pressure, papilloedema, and myoclonic jerks. Repeated comp uted tomography (CT) and magnetic resonance imaging (MRI) showed stabilised hydrocephalus with an enlarged left lateral ventricle. When the buy was 16 years old MRI revealed a choroid plexus cyst in the left lateral ventricle 2 cm in diameter, with a ball-valve type of obstruction of the foramen of Monro. CT stereoendoscopic resection of the wall of a large cyst filled wit h cerebrospinal fluid was performed, and two additional adnexal small cysts were coagulated using the bipolar coagulator, Diomed 25 laser and scissors ; the symptoms then regressed, except for superior bilateral altitudinal an opsia. Light and electron microscopy of the cyst wall is reported. The cyst was composed of collagenic connective tissue lined with a basal lamina lac king in epithelial cells. The preoperative and postoperative MRI are presen ted. Choroid plexus cysts localised in the anterior part of lateral ventric les are very rare, and all reported cases have been in male patients. Accor ding to the literature our case is only the third ever described in a child .