Sellar tumours include pituitary adenomas and craniopharyngioma.
Craniopharyngioma
A 'benign' epithelial tumour of the sellar region. There are two main types - adamantinomatous (children and adults) and papillary (adults)
Epidemiology
Biphasic age distribution - 5-15 years and 40-60 years of age. Gender equal.
Aetiology
Thought to arise from remnants of Rathke's pouch.
Clinical
Often presents with visual symptoms and endocrine abnormalities. Headache is common. Personality change and cognitive impairment is common in children.
Macroscopy
The tumour is typically 3-4 cm. The tumour is typically solid with cystic components; the cysts are filled with a thick dark green to brown liquid. Calcification is common. The papillary form usually lacks cysts and calcification.
Microscopy
Both types are formed by squamous epithelium. In the adamantinomatous form, the stratified squamous epithelium is arranged in cords or nests with areas of 'wet keratin' located extracellularly; there is peripheral pallisading at the edges of the tumour. The papillary form lacks the wet keratin calcification, and cysts. It is formed by sheets and papillae of stroma lined by squamous epithelium.
Genetics
Mutations in β-catenin are common in the adamantinomatous form but there are no specific mutations for the papillary form.
Pituitary tumours
Pituitary adenomas are the most common tumour of the sellar region. They can be classified according to the type of hormone produced (or 'non-secretory' if nothing produced).
Epidemiology
Most tumours occur in adults (35-60). Females are more common affected.
Aetiology
Unknown
Clinical features
Large tumours (often prolactinoma, growth hormone adenomas, non-secretory adenomas) may present with cranial nerve symptoms due to growth into the cavernous sinus and compression of the optic nerves (or alternatively III/IV/VI).
Hormone secretory tumours may present with a constellation of symptoms:
- Prolactinoma may present with galactorrhoea (in men or women), or infertility/amenorrhoea in women.
- GH-adenoma may present with gigantism (in children) or acromegaly (in adults)
- ACTH adenoma may present with Cushing's syndrome (and is known as Cushing's disease). This includes proximal muscle weakness, obesity, moon facies, hyperglycaemia and thinning of the skin as well as immunosuppression.
- TSH adenomas may present with hyperthyroidism
- Gonadotroph adenomas may present with hypogonadism or precocious puberty
Any tumour large enough may compress the normal pituitary gland and cause hypopituitarism of the other hormones (or all hormones) as well as diabetes insipidus from disruption of the posterior pituitary and lack of ADH secretion.
Pathological features
Macroscopically the tumours are cream, soft and gelatinous. Microscopically they are comprised of large, monomorphic, polygonal cells with minimal stroma - this helps to differentiate normal pituitary from adenoma. Rarely, there may be invasion (atypical adenoma) associated with TP53 mutation and high Ki-67 staining.
