Tumours within the pituitary fossa may be functional and sectrete trophic factors. However, more commonly they are non-functional and are space-occupying lesions. Pressure on neighbouring structures causes clinical signs, for example:
- Pressure on the optic chiasma produces ocular signs.
- Pressure on the hypothalamus may lead to Frohlich's adiposogenital syndrome.
- Pressure on the neurohyposphysis may lead to failure of ADH secretion. This will allow large volumes of water to be lost form the kidney; Diabetes Insipidus.
Neoplasia may be derived from:
- Pituitary itself.
- Surrounding brain tissue.
Neoplasia usually occurs in the pars intermedia of the anterior pituitary and compresses the hypothalamus.
- Polyuria and polydipsia.
- Increased appetite reulting in increased food intake and downregulation of insulin receptors. This leads to a hyperglycaemia.
- Muscle wekaness.