Pathology
MICROSCOPIC DESCRIPTION: 1,2. The sections show a moderately cellular tumour, forming well-defined papillary structures. Some psammoma bodies are noted. The tumour cells are cuboidal to columnar in shape. They have ovoid nuclei and small nucleoli. No mitoses are seen. There is no microvascular proliferation or necrosis. No evidence of brain invasion is identified. The tumour cells are focally transthyretin positive. They are TTF-1, thyroglobulin and BER-EP4 negative. The features are those of choroid plexus papilloma.
DIAGNOSIS: 1,2. Posterior fossa lesion: Choroid plexus papilloma.