Endocrine Abstracts

A 51-year-old man presented to an optometrist with a 3-week history of visual impairment following a minor headache. He was found to have reduced visual acuity 6/24 in both eyes and a dense bitemporal hemianopia and was referred urgently to Musgrove Park Emergency Department. MRI brain showed a cystic bleed from a pituitary macroadenoma, 30 mm in diameter, with compression of the optic chiasm. He had no clinical features of Cushing’s or other hormone excess or deficiency and thyroid function, prolactin, FSH/LH, testosterone, 0900 h cortisol (672 nmol/l), IGF1, and electrolytes were normal. He underwent an urgent transphenoidal resection performed in Queen’s Square, London and had an excellent recovery in vision and an intact pituitary axis postoperatively. The histology showed focal weak positivity to ACTH with ~20% of cell expression and a Ki-67<3%. He had a normal overnight dexamethasone suppression test (cortisol 25 nmol/l) consistent with diagnosis of silent corticotroph adenoma (SCA); the acute presentation likely secondary to subacute apoplexy due to pituitary haemorrhage. He will be followed up via the pituitary MDT with serial MRIs and pituitary hormone testing. SCAs show positive immunohistochemical staining for ACTH but are not associated with clinical or laboratory features of hypercortisolaemia and account for 1–6% of all surgically removed pituitary adenomas. At presentation most are macroadenomas with suprasellar extension; hence symptoms of mass effect are usually the first signs. It is not understood why SCAs do not cause cortisol excess but is thought to be due to molecular differences and altered cellular processing. A low Ki-67 index implies the tumour is less invasive but it has not been shown to predict recurrence. SCAs are no more likely to recur than null cell tumours but if they do they are typically more aggressive and so close follow-up is required.