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A circumscribed mass expands the pituitary fossa and stretches residual normal pituitary tissue around its periphery. There is no compression on the optic nerves or chiasm.
Additionally, the corpus callosum appears mildly dysplastic. The rostrum is absent and the splenium small.
The patient went on to have a resection.
The sections show a moderately hypercellular tumour. This is composed of lobules of cells with uniform round and oval vesicular nuclei and a variable amount of pale eosinophilic cytoplasm. Separate from the lobules, there is a haphazard arrangement of variably sized solid aggregates of tumour cells within a fibrous stroma. A narrow rim of normal anterior pituitary tissue is present along one edge of the tumour. No mitotic figures or areas of necrosis are identified.
Immunohistochemistry shows patchy strong staining in tumour cells for LH and there is strong diffuse nuclear staining for steroidogenic factor (SF-1). Tumour cells also show moderate staining for synaptophysin. Several small cystic structures, lined by Rathke's cleft type epithelium, are noted within the tumour. Epithelial cells lining these structures show strong cytoplasmic immunostaining for pancytokeratin AE1/AE3. Scattered S-100 +ve folliculo-stellate cells are noted admixed with tumour cells. No immunostaining for growth hormone, prolactin, ACTH, FSH, TSH, p40, GFAP, TTF-1, HBME-1 or cytokeratins CK7, CK20, CK5&6 and CK19 is seen in tumour cells. The topoisomerase labelling index is approximately 2%.
Silent gonadotroph cell pituitary macroadenoma.