Pituitary macroadenoma - encasing carotid
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MRI of the brain demonstrates a mass apparently centred on the left cavernous sinus and extending to abutt the pituitary gland. It encases the internal carotid artery without narrowing it.
The patient went on to have surgery.
The biopsy shows a tumour composed of sheets, nests and cords of intermediate-sized cells with pale cytoplasm. Admixed with the tumour are numerous cholesterol clefts with surrounding giant cells. There are scattered hemosiderin deposits as well.
Immunohistochemical stains show the tumour cells are strongly positive for synaptophysin and negative for chromogranin. There are rare cells positive for ACTH and prolactin and a small cluster of cells positive for LH/FSH. Other stains are negative. The vast majority of cells are negative for all markers except synaptophysin. This is tumour is best considered a null cell adenoma.
The finding of cholesterol clefts with granulomatous reaction is very unusual in pituitary adenomas, but has been previously reported in the literature and is thought to be secondary to focal infarction of the tumour 1.
- 1. Yokoyama S, et al. Pituitary Adenoma with Cholesterol Clefts. Endocrine Pathology 1998; 9:91-5.