Primary carcinoma of the pituitary gland is rare, but a metastatic tumour from a primary breast, lung, or kidney may occur in the hypothalamus and produce pituitary function.

CLINICAL FEATURES

Clinical features depend on the following three factors:

1. The size of the tumour in the pituitary gland & the effect of that tumour on surrounding structures (local complications)

2. There may be hypersecretion of hormones.

3. There may be hyposecretion of hormones due to compression of normal tissue by the tumour.

Local complications

• Upward extension: compression of the optic chiasma causing visual field defects.

Lateral extension into cavernous sinus causing dysfunction of cranial nerve 3, 4 and 6.

The stretch of the dura mater causes headache which is the most constant but least specific symptom.

Interruption of CSF flow causing hydrocephalus.

Increased hormone secretion

Acidophilic adenomas usually secrete excessive growth hormone that leads to acromegaly or gigantism.

Basophilic adenomas usually cause excessive ACTH secretion that leads to Cushing’s disease and Nelson’s syndrome.

Chromophobe adenomas, they are also called prolactinomas, secrete an excessive amount of prolactin.

Non-functioning adenomas: tumours that do not cause clinically apparent excess hormone secretion are called non-functioning adenomas (they are usually chromophobe adenomas).