Pineal region meningioma

Case contributed by Assoc Prof Frank Gaillard

Presentation

Patient presenting with headache and failure of up-gaze.

Patient Data

Age: 40 years
Gender: Female

CT brain

CT

A large well circumscribed mass is located in the pineal region. It is slightly hyperdense on precontrast imaging and demonstrates vivid contrast enhancement. It severely distorts the midbrain, compressing the aqueduct with marked obstructive hydrocephalus. A focus of increased density, probably calcium is seen immediately below the mass, possibly representing displaced pineal calcifications. 

MRI brain

MRI

A large well circumscribed mass is located in the pineal region. It is isointense to grey matter on both T1 and T2 weighted imaging with a central region of lower T2 signal (possibly due to a vascular core). It demonstrates vivid contrast enhancement. Restricted diffusion is seen throughout most of the mass, sparing the central region. 

It severely distorts the midbrain, compressing the aqueduct with marked obstructive hydrocephalus. Best seen on sagittal post contrast T1 images, a small nodule to tissue is seen immediately below the mass which represents the tectal plate, and given the calcification on CT possibly possibly also a displaced pineal gland. 

The internal cerebral veins are located above and the basal veins of Rosenthal below and lateral to the mass. 

Annotated images

Annotated image

A well circumscribed mass (yellow dotted line) is isodense to grey matter and demonstrates vivid enhancement. Posterosuperiorly (blue arrow) it appear continuous with the falx (red dotted line) and appears to displace the tectum and probably pineal gland inferiorly (green dotted line). 

The patient went on to have a posterior fossa (sub-tentorial) craniotomy and resection of this tumor. 

Histology

The sections  show multiple  fragments  of tumor,  some  associated with a densely fibrous  membrane consistent  with dura mater.   The tumor shows a variety of growth patterns, including fascicular areas, areas with abundant collagenous fibrous  tissue between  cells and foci of  whorl formation.  A very  occasional  psammoma  body is  noted.   Individual  tumor  cells are elongate, with fairly  abundant  eosinophilic cytoplasm,  often with poorly circumscribed cytoplasmic outlines.   Nuclei are generally rounded or oval, with finely granular  nucleoplasm,  sometimes with  cytoplasmic inclusions.

There are areas of the tumor where cellularity is high, with large crowded nuclei and cells with raised nuclear  to cytoplasmic ratio.  In such areas, the mitotic  count is  up to 10  per 10HPF.   The  features are  those of a meningioma, WHO grade 2.   No cerebral tissue is  recognized and no comment can be made about cerebral invasion.

FINAL DIAGNOSIS:  Pineal  region  tumor -  meningioma,  WHO  grade  2.

Case Discussion

A meningioma, is an uncommon cause of pineal mass. As always it is important to remember that some conditions can occur in unusual places, and one should not limit a differential only to lesions which are characteristic of a particular region. 

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