Pituitary and hypothalamic tumours
How tumours of the anterior pituitary cause disease by hormone excess (prolactin, growth hormone, ACTH) or by pressing on the optic chiasm and the normal gland, and how craniopharyngioma and other masses above the sella damage the hypothalamus.
By the end, you can
- Relate the anterior pituitary cell lineages and their control by the hypothalamus to the tumour types that arise from them.
- Explain how prolactin, growth hormone and ACTH excess produce their clinical pictures.
- Explain how a macroadenoma causes bitemporal hemianopia, hypopituitarism, the stalk effect and apoplexy.
- Describe the origin, two types and effects of craniopharyngioma, and name other suprasellar masses.
- Recognise the classic appearances, size and lineage classes and the hormone, visual field and MRI tests of pituitary and sellar tumours, and explain how dopamine agonists, somatostatin analogues, pegvisomant, trans-sphenoidal surgery and hormone replacement act on the mechanism.
What it is
Pituitary neuroendocrine tumours (PitNETs), still widely called pituitary adenomas, are clonal tumours of anterior pituitary cells; they cause disease by secreting a hormone or by mass effect on the optic chiasm, the normal gland and nearby structures. Hypothalamic and suprasellar tumours, above all craniopharyngioma, arise around the pituitary stalk and damage the hypothalamus, the visual pathway and pituitary control.
5 types to tell apart
- Functioning PitNET
- Secretes excess hormone: prolactin (commonest), growth hormone, ACTH, or rarely TSH.
- Non-functioning PitNET
- No clinical hormone excess (mostly gonadotroph tumours); found because of its size, usually as a macroadenoma.
- Microadenoma and macroadenoma
- Under 1 cm and 1 cm or more; only macroadenomas compress surrounding structures.
- Craniopharyngioma
- A suprasellar tumour from Rathke pouch remnants: adamantinomatous (CTNNB1) and papillary (BRAF V600E) types.
- Other suprasellar masses
- Germinoma, optic pathway and hypothalamic glioma, hypothalamic hamartoma, meningioma and metastasis.
US spelling: tumours → tumors.
Normal function
A small gland in a crowded space
The pituitary sits in the sella turcica, a hollow in the sphenoid bone, hanging from the by the . The develops from Rathke’s pouch, an outgrowth of the embryonic mouth; the is a downgrowth of the brain that stores and releases vasopressin (AVP) and oxytocin made by hypothalamic neurones.
Anterior pituitary cells belong to three lineages, set by transcription factors: PIT1 cells make growth hormone (somatotrophs), prolactin (lactotrophs) or TSH (thyrotrophs); TPIT cells make ACTH (corticotrophs); SF1 cells make LH and FSH (gonadotrophs). Hypothalamic hormones reach them through portal vessels in the stalk. Prolactin is the exception to stimulation: hypothalamic dopamine holds it down constantly.
The gland has close neighbours: the just above it, separated by a fold of dura (the diaphragma sellae); the cavernous sinuses on each side, carrying the internal carotid arteries and the nerves that move the eyes; and the below.
Underlying change · Step 1 of 4
A clone of one anterior pituitary cell type
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 4
Too much prolactin, growth hormone or ACTH
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 4
Pressing on the chiasm, the gland and the stalk
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 4
Craniopharyngioma and other masses above the sella
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .