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REGUB: Adrenal & Parathyroid Pathology (iii) (Phaeochromocytoma…
REGUB: Adrenal & Parathyroid Pathology (iii)
Phaeochromocytoma
uncommon
surgically correctable HTN
affects 0.1-0.3% of hypertensive patients
rule of 10s
10% in extra-adrenal paraganglia (paragangliomas)
10% bilat (50% in familial cases)
10% malignant in adrenals (20-340% malignant @ extra-adrenal sites)
over 25% occur with familial syndromes (germline mutations)
MEN (RET)
type 1 neurofibromatosis (NF1)
VHL
succinate dehydrogenase complex (SDHB, SDHC, SDND)
histology: small nests of polygonal/spindle cells - "Zellballen"
HTN (sustained in 2/3), tachycardia, palpitations, headaches, sweating, tremor, abdo/chest pain, paroxysmal episodes of HTN (exercise, stress, change in posture, palpation in region of tumour can cause catechol release)
catechol CM: myocardial instability, ventricular arrhythmias due to vasomotor constriction of myocardial circulation
Dx: 24 hr urinary collection of catechols + metabolites (e.g. VMA - vanillylmandelic acid + metanephrines)
Tx: surgical excision after pre-op + intra-op medication with adrenergic blocking agents (prevent adrenal crisis)
paragangliomas
carotid body tumours
chemodectomas (jugulotympanic body tumours)
10-40% malignant (recur after resection)
10% met widely
15-25% multicentric
Parathyroid hyperfunction
primary
overproduction of PTH
hypercalcaemia
adenoma in 75-80%: solitary, 0.5-5g, well-circumscribed, delicate capsule, other glands normal size/shrunken
primary hyperplasia in 10-15%: diffuse or nodular, occur sporadically or as part of MEN
carc in <5%: dx made on invasion of surrounding tissues + mets
secondary
any condition a/w chronic decrease in Ca, leads to compensatory over activity of parathyroid gland
most common cause = renal failure
chronic renal insufficiency - decreased phosphate excretion - hyperphosphataemia - suppresses Ca - stims PTH to bring Ca near normal
tertiary
in a minority
parathyroid activity autonomous + excessive
tx = parathyroidectomy
hypercalc
"painful bones, renal stones, abdo groans, psychic moans"
osteoporosis (fractures)
osteitis fibrosa cystica (bones abnormally weak + deformed due to hyperparathyroidism)
chronic renal insufficiency
nephrolithiasis
nephrocalcinosis (deposition of Ca salts renal parenchyma)
constipation, anorexia, nausea, vomting, acute pancreatitis, PUD, gallstones
altered concentration, depression, confusion, seizures, weakness, fatigue
aortic/mitral valve calcifications (cardiac manifestations)
Hypoparathyroidism
causes
inadvertent surgical removal during thyroidectomy - mistake for lymph nodes
congenital absence (DiGeorge syndrome - a/w thymic aplasia)
primary idiopathic atrophy (AI) - abs against Ca sensing Rs
familial - presents in childhood
hypocalcaemia
numbness/tingling in extremities + perioral region
muscle cramps
bronchospasm/laryngospasm/seizures)
Chvostek's sign - muscle spasms in mouth/eye/nose with tapping of facial N
Trousseau's sign - carpopedal (hand/foot) spasms with inflation of sphygmomanometer 20mmHg above sys BP
intracranial manifestations (parkinsonism-like movement)
CV manifestations - conduction defect with prolonged QT interval
MEN Syndromes
familial - AD
neoplasia/hyperplasia of several endocrine glands
type 1 (Wermer's syndrome)
3 Ps: parathyroid, pit (prolactinomas), pancreatic islet cells
most common feature = primary hyperparathyroidism
genetic defect in TSG MEN1 (chromo 11q13)
type 2
2 distinct groups
both have activating mutations of RET photo-oncogene @ chromo 10q11.2
2A (simple sundrome) - medullary carc of thyroid, phaechromocytoma, parathyroid hyperplasia
familial medially thyroid cancer: variant of MEN 2A - no other manifestations of MEN 2A - typically occurs @ older age + follows a more indolent course
2B
medullary carc of thyroid, pheochromocytoma + extra endocrine manifestations (ganglioneuromas of mucosal sites, "marfanoid habitus" - long bones of axial skeleton, long limbs, arm span>height), do not get primary hyperparathyroidism
tumours occur @ younger age than sporadic neoplasms
often multifocal
tumours usually preceded by asymp stage of endocrine hyperplasia
more aggressive + higher rate of recurrence than sporadic tumours
any patient carrying a germline RET mutation is advised to have prophylactic thyroidectomy to prevent the inevitable development of medullary carc