pit tumour non-functioning Flashcards
def pit tumour
Pituitary adenomas that do not cause a characteristic hormone hypersecretion syndrome (null cell and the majority of gonadotroph adenomas) are referred to as clinically non-functional adenomas
RF pit tumour
multiple endocrine neoplasia type-1 (MEN-1)
familial isolated pituitary adenomas (FIPA)
carney complex (CNC)
aetiology pit tumour
unknown
Pituitary adenomas are monoclonal in origin, suggesting intrinsic genetic alterations as initiating events
Hypothalamic hormones and other local growth factors may have an important role in promoting the growth of already transformed pituitary cell clones and also the expansion of small adenomas into large or invasive tumours.
Abnormal cell proliferation, differentiation, and hormone secretion may result from ‘gain of function’ (i.e, activating mutations of oncogenes) or ‘loss of function’ (i.e., inactivating mutations of tumour suppressor genes).
classification pit tumou
They may be divided by size: a microadenoma is a tumour <1cm across, and a macroadenoma is >1cm.
path pit tumour
Non-functional pituitary adenomas are associated with hypermethylation of the p16 locus, cyclin dependent kinase inhibitor 2A (CDKN2A) gene, on chromosome 9p21.3. The CDKN2A gene is a tumour suppressor gene, and its product, CDKN2A protein, is important in the control of G to S phase transition in the cell cycle via inhibition of CDK4-mediated retinoblastoma protein 1 (RB1) phosphorylation. Hypermethylation of this gene inactivates the gene with no CDKN2A protein synthesis, leading to unregulated cell growth
Pituitary adenoma cells, particularly from clinically non-functional pituitary adenomas (CNFPAs), express PPAR-gamma in vitro.
Pituitary tumour transforming gene (PTTG) overexpression has been implicated in pituitary tumorigenesis. PTTG mRNA is elevated in non-functional tumours and growth hormone- and prolactin-producing tumours. PTTG protein is involved in intracellular signalling.[33] PTTG induces fibroblast growth factor 2 (FGF-2) expression, which mediates cell growth and angiogenesis
epi pit tumour
10% intracranial tumours
Pituitary adenomas are the third most common intracranial neoplasms (behind meningiomas and astrocytomas),
30-60yrs
presentation may be earlier in women (typically at 20 to 45 years) than in men (35 to 60 years), owing to the greater frequency of prolactinomas in young women.
sx pit tumour
symptoms caused by pressure or hypopituitarism
headache
visual field defects - bilateral temporal hemi-anopia, due to compression of the optic chiasm
disturbance of hypothalamic centres of T°, sleep, and appetite
erectile dysfunction
soft small testes
gynaecomastia
amenorrhoea
infertility
breast atrophy
loss of libido
hot flushes
diaphoresis
weight gain
fatigue
anorexia
nausea
vomiting
weakness
signs pit tumour
decreased visual acuity
bitemporal hemianopia
presence of RF
erosion through floor of sella leading to CSF rhinorrhoea
diabetes insipidus
ix pit tumour
MRI defines intra- and supra-sellar extension
accurate assessment of visual fields
screening tests - PRL. IGF-1, ACTH, cortisol, TFTs, LH/FSH, testosterone on men, short synacthen test
glucose tolerance test if acromegaly suspected
water deprivation test if diabetes insipidus suspected
