Choroid plexus papilloma

Case contributed by RMH Neuropathology

Presentation

Not available.

Patient Data

Age: 20
Gender: Male
Modality: CT

There is a solid hyperdense mass in the midline of the posterior fossa. It seems intimately related in the inferior vermis, abutting in the floor of the fourth ventricle and extending through the foramen magnum.

The mass has homogenous enhancement with no diffusion restriction. There are prominent flow voids within the tumour. I note that the tumour is hyperdense on a non-contrast CT.

Mild hydrocephalus. 

The remainder of the brain is unremarkable.

Modality: MRI

There is a lobulated mass in the midline of the posterior fossa measuring 24 x 32 x 30 mm (trans, AP, CC). It is intimately related in the inferior vermis and extends into the left cerebellar hemisphere. It abuts the floor of the fourth ventricle and partially effaces it and it extends through the foramen magnum and displaces the medulla anteriorly.

The mass has homogenous enhancement with no diffusion restriction. There are prominent flow voids within the tumour. I note that the tumour is hyperdense on a non-contrast CT.

Right frontal approach ventricular drain with tip in the right lateral ventricle. Mild hydrocephalus persists. The cisternal magna is enlarged.The remainder of the brain is unremarkable with no evidence of CSF seeding.

IMPRESSION: Vascular appearing posterior fossa mass centred in the inferior cerebellar with MRI appearances not pathognomonic of any one particular entity. The differential diagnosis is between choroid plexus papilloma, haemangioblastoma, ependymoma and pilocytic astrocytoma. Medulloblastoma is unlikely due to facilitated diffusion. 

Modality: Pathology

MICROSCOPIC DESCRIPTION: The sections show a moderately cellular papillary tumour. It has well-developed papillae with central fibrovascular cores. The lining cells have mildly enlarged and slightly clefted nuclei, generally small nucleoli and moderate amounts of clear foamy to pale eosinophilic cytoplasm. True ependymal rosettes or perivascular pseudorosettes are absent. Mitoses are inconspicuous. There are increased numbers of blood vessels at the tumour periphery but no microvascular proliferation is seen. No necrosis is identified. The tumour cells are diffusely CAM5.2 and focally GFAP positive. The topoisomerase index is 2%. They are transthyretin, synaptophysin, inhibin, EMA, CD10, Napsin-A, thyroglobulin and TTF-1 negative. The features are those of choroid plexus papilloma.

DIAGNOSIS: Posterior fossa tumour: Choroid plexus papilloma (WHO Grade I).

Case Discussion

Choroid plexus papilloma is an uncommon, benign neuroepithelial intraventricular tumour which can occur in both the paediatric (commoner) and adult population. 

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Case Information

rID: 34951
Case created: 16th Mar 2015
Last edited: 7th Sep 2015
Inclusion in quiz mode: Included

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