Besides the pituitary adenoma, several other masses arise in the sellar region. They come from different tissues: remnants of Rathke’s pouch, the meninges, cancers elsewhere in the body, and the hypothalamus and optic pathways. Rathke’s pouch is the embryonic pouch that contributes to the anterior pituitary, and it gives rise to the first two masses below.
Craniopharyngiomas
Craniopharyngiomas are benign, cystic masses that present with visual field deficit, headache, and a variable degree of hypopituitarism, an underactive pituitary. They are derived from the Rathke’s pouches near the pituitary stalk, which mostly extend to the suprasellar cistern. Their age distribution is bimodal, peaking in children aged 5-14 years and again in adults aged 50-75 years, so they are diagnosed in both children and adults. Among the younger patients, clinical complaints often come from increased intracranial pressure: headache, vomiting, papilledema (swelling of the optic disc) and hydrocephalus.
The other symptoms of craniopharyngiomas are weight gain accompanied by metabolic syndrome, sleep disturbances and cognitive changes. At diagnosis, hypopituitarism is documented in up to 90% and diabetes insipidus in about 10% of cases.
Treatment is usually based on transcranial or transsphenoidal surgery with post-operative radiotherapy.
Rathke’s cyst
Failure of developmental obliteration of Rathke’s pouch can lead to the formation of a Rathke’s cyst, a small cyst that can compress the stalk. The main clinical symptoms are:
- diabetes insipidus
- hyperprolactinemia
Meningiomas
It is difficult to distinguish a non-functioning pituitary adenoma from a meningioma arising in the sella turcica. Meningiomas may cause compressive symptoms in the patient.
Pituitary metastases
Pituitary metastases occur in 3% of cancer patients, mostly in the posterior pituitary gland, where they can cause diabetes insipidus. About half of pituitary masses come from breast cancer.
Hypothalamic hamartomas and gangliocytomas
Hypothalamic hamartomas and gangliocytomas may arise from oligodendrocytes, astrocytes, or neurons. These tumors can over-produce some hypothalamic hormones, namely GnRH, GHRH or CRH. Children with the GnRH-producing type manifest with precocious puberty, psychomotor delay, and laughing-associated seizures.
Hypothalamic gliomas and optic gliomas
Hypothalamic gliomas and optic gliomas mostly occur in children, and they are more aggressive in adults.
None of these masses arises from the gland’s own hormone-producing cells, which is what sets the pituitary adenoma apart.