4. Adrenal Flashcards
Normal anatomy (4)
Paired retroperitoneal glands on top of each kidney.
Right is triangular in shape, left is more crescent shaped.
They become more “pancake” or discoid shaped if the kidney is congenitally absent.
3 arteries supply them (superior from inferior phrenic, middle from aorta, inferior from renal artery).
Venous drainage into the IVC on right and left renal vein on left.
Adrenal gland - zones (4)
Cortex (outer to inner)
- Zona Glomerulosa: produces aldosterone
- Zona fasciculata: produces cortisol
- Zona Reticularis: produces androgens
Medulla: produces catecholamines
Normal ultrasound (4)
Can be seen in babies.
Cortex is hypoechoic, medulla is hyperechoic.
Gives adrenal “triple stripe” appearance (dark cortex, bright medulla, dark cortex).
In adults, need to use CT or MRI.
Adrenal hypertrophy - causes (2)
21-Hydroxylase deficiency
Cushing syndrome
21-Hydroxylase deficiency (3)
Congenital adrenal hypertrophy, caused by 21-hydroxylase deficiency in >90%.
Will manifest as either genital ambiguity (girls) or salt losing pathology in boys (can be life threatening).
Adrenal limb width >4mm on imaging, with loss of central hyperechoic stripe.
Cushing syndrome (3)
Too much cortisol.
Commonly due to pituitary adenoma (75%), or ectopic production from small cell lung cancer. Will cause bilateral adrenal gland hyperplasia.
Less commonly due to adrenal adenoma.
Adrenal haemorrhage causes (3)
Stress
Trauma
Waterhouse-Friderichsen Syndrome
Stress (adrenal haemorrhage) (5)
Seen after breech birth usually, can be seen with foetal distress and congenital syphillis.
US: evolves from hyperechoic, to isoechoic to hypoechoic.
Calcification is often end result.
Should be avascular on US.
Can occur bilaterally, but favours right side.
Serial US or MRI can differentiate it from cystic neuroblastoma (haemorrhage will get smaller).
Trauma (adrenal haemorrhage) (2)
More common on right.
Usually shown in adult on CT
Phaeocromocytoma (4)
Uncommon, usually large at presentation (>3cm).
Usually heterogenous mass on CT.
T2 bright on MRI.
MIBG can also be used to see them.
Phaeochromocytoma - trivia (6)
10% are extra-adrenal (Organ of Kuckerdandl, usually at IMA), 10% bilateral, 10% in children, 10% hereditary, 10% are inactive.
Associated syndromes
- VHL.
- MEN IIa and IIb
- NF-1, Sturge weber, TS
Carney triad
- Extra-adrenal Phaeo, GIST, Pulmonary chondroma (hamartoma).
Myelolipoma (6)
Benign tumour containing bulk fat.
1/4 have calcifications.
Big >4cm, can bleed and present with retroperitoneal haemorrhage.
Associated with endocrine disorders (Cushings, Congenital adrenal hyperplasia, Conns).
Non functional tumours.
Cyst (3)
Often unilateral, can be any size.
Bigger ones can bleed.
Thin wall. Non-enhancing.
Mets (3)
Breast, lung, melanoma.
No specific imaging findings, look like lipid poor adenomas.
If known primary, and not adenoma, probably met.
Cortical carcinoma (3)
Large (4-10cm), may be functional (Cushings) and calcify 20% of cases.
Often met everywhere, direct invasion is initially most common.
Adrenal carcinoma is unlikely to be <5cm, often central necrosis.
