Endo Flashcards
Adrenal anatomy
The adrenal glands are paired retroperitoneal glands that sit on each kidney.
The right gland is triangular in shape, and the left gland tends to be more crescent shaped. If
the kidney is congenitally absent the glands will be more flat, straight, discoid, or “pancake ”
in appearance. Each gland gets arterial blood from three arteries (superior from the inferior
phrenic, middle from the aorta, and inferior from the renal artery). The venous drainage is via
just one main vein (on the right into the IVC, on the left into the left renal vein).
adrenal cortex layers
Zona glomerulosa
zona fasciculata
zona reticularis
Adrenal 4 zones
Zona Glomerulosa: Makes Aldosterone - prolonged stimulation here leads to hypertrophy. Zona Fasciculata: Makes Cortisol Zona Reticularis — Makes Androgens Medulla - Makes Catecholamines
Adrenal Ultrasound Cases - Gamesmanship
overview
If you get shown an adrenal case on ultrasound, then you are almost certainly dealing with a
peds case. What that means is that your choices are narrowed down to: (a) normal,
(b) neuroblastoma, (c) hemorrhage, and (d) hyperplasia.
Adrenal Ultrasound Cases - Gamesmanship
normal
In babies, the cortex is hypoechoic, and the medulla is hyperechoic. This gives
the adrenal a triple stripe appearance (dark cortex, bright medulla, dark cortex).
normal adrenal us quick
Hypoechoic Cortex, Hyperechoic Medulla, Hypoechoic Cortex
- like an Oreo, with a cream filling.
Neuroblastoma (adrenal)
I talk about this a ton in the peds chapter. To rehash the
important parts, they form in the adrenal medulla
(usually), and typically look like an enlarged gland with
a hyperechoic component. Having said that they can
have cystic components and look like hemorrhage. For
the purpose o f multiple choice I ’d go with hyperechoic.
Adrenal hemorrhage
overview
This occurs most commonly in the setting of
trauma or stress (neonates). What this typically
looks like on ultrasound is an enlarged gland with
an anechoic component. With time, the clot
changes and it can be more and more echogenic.
So basically, it can look like anything but for the
purpose o f multiple choice I’d go with anechoic.
Adrenal hemorrhage
stress
It’s classically seen after a breech birth, but can also be seen with fetal
distress, and congenital syphilis. Imaging features change based on the timing of
hemorrhage. Calcification is often the end result (that could be shown on CT or
MR). It should be avascular. This can occur bilaterally, but favors the right side
(75%).
o Classic Next Step: Serial ultrasounds (or MRI) can differentiate it from a
cystic neuroblastoma. The hemorrhage will get smaller (cancer will not).
o So which is it? Serial ultrasound or MRI? - If forced to pick you want serial
ultrasounds. It’s cheaper and doesn’t require sedation.
Adrenal hemorrhage
trauma
This is going to be an adult (in the setting o f trauma). Most likely it will be shown on CT. It’s more common on the right.
Waterhouse-Friderichsen Syndrome
Hemorrhage o f the adrenal in the
setting of fulminant meningitis (from Neisseria Meningitidis).
Adrenal hyperplasia
overview
What this typically looks like on ultrasound is a “big
adrenal” that “looks like a brain.” So what does “b ig ”
mean ? Most sources will say longer than 20mm, and a
limb that is thicker than 4 mm (although this is debated -
and will likely not be asked). For the purpose o f multiple
choice I would say that if they stick calibers on it. then it is
too big. So what does “looks like a brain ” mean ? That
means the surface is wrinkled, like it has gyri and sulci.
Adrenal hyperplasia
21-Hydroxylase Deficiency:
Congenital adrenal hypertrophy is caused by 21-
hydroxylase deficiency in > 90% o f cases. It will manifest clinically as either genital
ambiguity (girls) or some salt losing pathology (boys). The salt losing can actually be
life threatening. The look on imaging is adrenal limb width greater than 4mm. In some
cases you lose the central hyperechoic stripe (the whole thing looks like cortex).
Adrenal hyperplasia
Too much cortisol
from overproduction o f ACTH - which results in bilateral
adrenal gland hyperplasia. If someone wanted to be a real asshole they could get into the
weeds with vocabulary. For example, the “Disease” vs “Syndrome” THIS vs THAT:
I say “Genital ambiguity”, you say
21-Hydroxylase Deficiency
Cushing Disease:
This is an overproduction o f ACTH by a pituitary adenoma,
resulting in too much cortisol. This is actually the most common cause o f excess cortisol (75%).
Cushing Syndrome
The “syndrome” is basically a variety o f causes resulting
in common symptoms. So you can have overproduction o f ACTH by an ACTH
secreting tumor (classic step 1 example is the small cell lung tumor), or
overproduction o f ACTH via an adrenal adenoma (these cases will not have
hyperplasia), or you can have straight up primary adrenal hyperplasia. You could even
get the “syndrome” by taking chronic high dose steroids. Any way you end up with a
fat moon face and big gross lines all over you belly counts as “syndrome.”
Adrenal rapid review
normal
" Triple Stripe ■ Hypoechoic Cortex, “ Hyperechoic Medulla, ' Hypoechoic Cortex ■ Smooth Surface
Adrenal rapid review
hyperplasia
’ Big (longer than 20mm)
■ Looks like a brain (wrinkled surface)
‘ Can sometimes lose the central bright layer
- “Genital ambiguity”, = 21-OH Deficiency
Adrenal rapid review
hemorrhage
■ Big with an anechoic (or echogenic) component
■ Gets smaller over time
- Seen with “stress” or trauma
Adrenal rapid review
neuroblastoma
” Big with an echogenic (or anechoic) component
- Does NOT gets smaller over time
Adrenal Adenoma
overview
These things are easily the most common tumor in the adrenal gland. Up to 8% o f people
have them. Proving it is an adenoma is an annoying (testable) problem.
Adrenal Adenoma
non con
less than 10 HU
Adrenal Adenoma
absolute washout
Enhanced CT - Delayed CT/
Enhanced CT - Unenhanced CT
x 100
Greater than 60% = Adenoma
Adrenal Adenoma
relative washout
Enhanced CT - Delayed CT /
Enhanced CT x 100
Greater than 40% = Adenoma
Adrenal ademo
hypervascular mets
Hypervascular mets (usually renal, less likely HCC) can mimic adenoma washout. Portal venous HU values > 120 should make you think about a met.
adrenal pheo
Along those lines Pheochromocytomas can also exhibit washout. The trick is the same,
if you are getting HU measurements > 120 on arterial or portal venous phase you can
NOT call the thing an adenoma.
adreanl adenoma mri
Look for drop out on in and out o f phase T l.
Real Life = Mass in Adrenal =
adenoma
Multiple Choice = Mass in the Adrenal =
possible stuffery
Although most adenomas are not functional,
Cushings (too much cortisol) and Conn’s (too
much aldosterone) can present as functional adenoma.
adrenal adenoma tips
• Adenoma are usually homogeneous. If they are showing you hemorrhage (in the absence of
trauma), calcifications, or necrosis you should start thinking about other things.
• Adenomas are usually small (less than 3 cm). The bigger the mass, the more likely it is to be a cancer. Hom> b ig ? Most people will say more than 4 cm = 70% chance cancer, and
more than 6 cm = 85% chance cancer. The exceptions are bulk fat (myelolipomas) or
biochemical catecholamines in the question stem (pheo) - those can be big.
• Bilateral Small = Probably adenoma
• Bilateral Large = Pheo or Met (Lung cancer)
• Portal Venous Phase HU > 120 — Probably a met (RCC, HCC) or pheo.
“Collision Tumors”
Two different tumors that smash together to look like one mass.
Usually one o f them is an adenoma. Remember adenoma should be homogenous and small.
If you see heterogenous morphology consider that you could have two tumors. FDG PET
and MRI can both usually tell if the tumor is actually a collision of two different tumors -
those would be the appropriate next steps.
Conn’s Syndrome
Syndrome o f excessive aldosterone production. This is most
commonly caused by a benign adenoma (70%). Cortical-carcinoma can also do it, but that
is much more rare and usually accompanied by hypercortisolism.
Pheochromocyioma
overview
Uncommon in real life (common on multiple choice tests). They are usually large at presentation
(larger than 3 cm). The look is variable (heterogenous, homogenous, cystic areas, calcifications,
sometimes even fat). Having said that, the most classic look is a heterogeneous mass with AVID
ENHANCEMENT. On MRI they are T2 bright. Both MIBG and Octreotide could be used (but
MIBG is better since Octreotide also uptakes in the kidney).
Pheochromocyioma
gamesmanship 1
The hyper enhancement washout trick. They could show you what looks like an adenoma study (multiple phases to calculate washout) - but with mega enhancement (HU > 120). Remember, I don't care what the fuck washout out numbers you get - if they show you HU measurements > 120 on arterial or portal venous phase you can NOT call the thing an adenoma.
Pheochromocyioma
gamesmanship 2
This thing isn’t
always in the adrenals. They can
be extra adrenal (organ of
Zuckerkandl - usually at the IMA).
Pheochromocyioma
rule of 10s
10% are extra adrenal (organ o f Zuckerkandl - usually at the IMA), 10% are bilateral, 10% are in children, 10% are hereditary, 10% are NOT active (no HTN).
Pheochromocyioma
syndromes
Associated syndromes: First think Von Hippel Lindau, then think MEN Ha and lib. Other things less likely to be tested include NF-1, Sturge Weber, and TS.
Pheochromocyioma
carney triad
- Extra-Adrenal Pheo, GIST, and Pulmonary Chondroma (hamartoma).
- Don ’/ confuse this with the Carney Complex (Cardiac Myxoma, and Skin Pigmentation).
