Pineal cyst obstructing aqueduct

Case contributed by Assoc Prof Frank Gaillard

Presentation

2 months of severe occipital headache.

Patient Data

Age: 45 years
Gender: Male

MRI brain

MRI

A lobulated 14 x 8 mm pineal cyst projects anteriorly to obstruct the upper margin of the cerebral aqueduct, with mild to moderate hydrocephalus and mild periventricular (transependymal) signal abnormality. 

Several small T2 hyperintense lesions, measuring up to 5 mm diameter inferiorly in the right pre-central gyrus, are in keeping with chronic small vessel ischemic  change, a little greater than expected for the patient's age, with no associated diffusion restriction or magnetic susceptibility. The remainder of the study is unremarkable.

Annotated image

Annotated image

A cystic pineal region mass (yellow dotted line) has prolapsed anteriorly and obstructed the superior aspect of the aqueduct (red). Hydrocephalus is present with inferior bowing of the floor of the third ventricle and ballooning of the supraoptic recess (blue) and infundibular recess (purple). 

As is the cases with all pineal gland masses the internal cerebral veins (orange) are located above the mass. 

The patient went on to have endoscopic resection of the mass. 

Histology

MICROSCOPIC DESCRIPTION: Serial sections show a small fragment of glial tissue which  incorporates a slit-like space. This is lined by a more compact layer  of glial tissue staining strongly for GFAP but with focal staining for  epithelial membrane antigen. Scattered single siderophages are noted  in tissue adjacent to the space and there are also scattered Rosenthal  fibers. No evidence of tumor is seen. No pineal parenchymal tissue is  identified. The features are of pineal cyst/pineal glial cyst.   

FINAL DIAGNOSIS: Pineal cyst

Case Discussion

Although pineal cysts are very common, and usually asymptomatic they can result in obstructive hydrocephalus, usually due to compression of the tectum. In this case the cyst has prolapsed into the aqueduct. 

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