Pituitary adenoma - null cell
Adult male presenting with bitemporal hemianopia.
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MRI demonstrates a mass arising out of the pituitary fossa and contacting the optic chiasm. It is of intermediate signal on T1 and FLAIR sequences, and enhances homogeneously. Features are consistent with a pituitary macroadenoma, which was confirmed at resection (null cell pituitary adenoma).
Paraffin sections show fragments of a moderately hypercellular adenoma. This is compsed of cells with round and oval vesicular nuclei and a moderate amount of pale cytoplasm, arranged in diffuse sheets intersected by thin-walled capillaries. No mitotic figures or areas of necrosis are seen. Scattered acini of normal anterior pituitary cells are admixed with tumour.
No immunostaining for growth hormone, prolactin, ACTH, FSH, LH or TSH is seen in tumour cells. The features are of null cell adenoma.