Paediatric Imaging

Pituitary adenoma

adenoma of the pituitary gland, uncommon in children. They may be seen in adolescents. About a quarter are non-functioning. The most commonly active adenomas are prolactin-secreting and result in delayed menarche. Less common are corticotropin-secreting adenomas and growth hormone-secreting adenomas. Adenomas in children are usually macroadenomas rather than microadenomas. Nonfunctioning adenomas typically present with short stature, delayed puberty and primary amenorrhoea in girls. Occasionally, visual disturbance is a presenting feature.

Imaging findings are similar to those seen in adults, with microadenomas appearing as small hypointense masses within the gland on non-contrast sequences. There may be deviation of the pituitary stalk and a convex upper border to the gland itself. Macroadenomas will obviously result in gland enlargement and might extend up into the suprasellar cistern. Compression of the optic chiasm and extension into the cavernous sinus is also possible. After contrast administration, microadenomas typically show no enhancement in the early stages (Fig.1). More delayed images show gradual enhancement of the adenoma. Macroadenomas enhance uniformly and intensely. Occasionally, pituitary apoplexy can occur with haemorrhage into a rapidly expanding adenoma. In these circumstances, T1-weighted sequences may show heterogeneous high signal on precontrast images due to the internal haemorrhage. This rapid enlargement of the gland often presents with acute headache and visual loss.

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Fig.1

Sagittal T1-weighted images pre- (a) and post- (b) intravenous gadolinium show a nonenhancing adenoma in the anterior lobe of the pituitary.
Pituitary adenoma, Fig.1 (a)
Pituitary adenoma, Fig.1 (b)