Pituitary tumour syndromes are the disorders of the pituitary gland and the sellar region, and the masses that grow there. A sellar mass is any tumour in the sella turcica. The most common one is the pituitary adenoma, a benign tumour of the hormone-making cells of the front of the gland.
One picture ties the parts together
The definition names the tumour; the question now is what such a tumour does to the gland.
The pituitary is the master gland of the endocrine system: it controls other endocrine organs through the stimulatory hormones it releases. It sits in the sella, where bone confines it. A mass harms the normal gland by squeezing it or by being a hormone-making tumour. So the harm comes in two ways: through the hormones the mass makes on its own, or by compressing the gland, its stalk and the structures beside it. Which of the two dominates, together with the cell the mass came from, decides how the mass presents and how it is treated. For an adenoma, the cell type it came from sets the hormone picture.
The gland and the masses around it
The harm is by hormones or by squeezing, so the reader needs the gland first, then the masses that sit beside it.
- The pituitary gland and its hormones: the pea-sized gland attached to the diencephalon, its two embryological parts, the hypothalamic control of both, and how gland height changes with age.
- Sellar masses and pituitary adenomas: the disorders of the sellar region, then adenomas classified by size and invasion, and by sporadic or familial origin.
- Other sellar masses: craniopharyngiomas, Rathke’s cyst, meningiomas, pituitary metastases and the hypothalamic tumours that grow in the same region.
The adenomas, from cell type to treatment
Of these masses the adenomas are the most common, so the list now turns to them.
- Pituitary adenoma types and frequency: the five cell types of the front of the gland, each of which gives rise to an adenoma, and how adenomas are classified by transcription factor and by hormone.
- Molecular pathogenesis of pituitary adenomas: how primary and promoting changes start an adenoma, and the genes that carry them, from GNAS and GPR101 to AIP.
- Clinical manifestations of sellar masses: headache, visual loss, stalk compression, cranial nerve involvement and pituitary apoplexy.
- Investigating a sellar mass: MRI, the management of incidentalomas, ophthalmologic assessment, the laboratory panel and histology when needed.
- Treatment of pituitary adenomas: prolactinomas are treated with drugs and other adenomas are operated on, with the treatment options for acromegaly, Cushing’s disease, TSH-producing and non-functioning tumours.
- Genetic syndromes associated with pituitary tumours: the tumour group defined by inheritance, namely MEN, Carney complex, McCune-Albright syndrome and familial acromegaly, each with its gene.
- Non-functioning and gonadotropin-producing adenomas: the tumour group defined by the absence of a hormone syndrome, which presents late through compression, and how stalk compression can mimic a prolactinoma.
Where to start
The list ends where the reader should begin, with the gland itself. Start with the pituitary gland and its hormones, because every later part compares a tumour with the normal gland. What does the normal gland do before anything grows in it?