Endocrine: Adrenal Flashcards
Arterial blood supply to the adrenal gland
3 Arteries feed the adrenal gland:
- Superior adrenal artery (from the inferior phrenic)
- Middle adrenal artery (from the aorta)
- Inferior adrenal artery (from the renal artery)
Venous drainage of the adrenal gland
Adrenal vein (to IVC on the right and to the left renal vein on the left)
What are the anatomical sections of the adrenal gland?
- Cortex (zona glomerulosa, zona fasciculata, zona reticularis)
- Medulla
Note: GFR for cortex zones.
What does the zona Granulosa make?
Aldosterone
Note: Gfr: SALT, sugar, sex (the deeper you go the sweeter it gets).
What does the zona fasciculate make?
Cortisol
Note: gFr: salt, SUGAR, sex (the deeper you go the sweeter it gets).
What does the zona reticular make?
Androgens
Note: gfR: salt, sugar, SEX (the deeper you go the sweeter it gets).
What does the adrenal medulla make?
Catecholamines
What is the normal size of the adrenal gland?
- Half the size of the kidney (second trimester)
- 1/3 size of the kidney (third trimester)
- 1/13 size of kidney (adulthood)
Adrenal gland (cortex appears hypoechoic and medulla appears hyperechoic)
Pancake adrenal sign (ipsilateral renal agenesis, which prevents the adrenal from becoming triangular/crescentic and instead appears flat and pancake-like)
Fetal ultrasound, what are the black arrows pointing to?
Horseshoe adrenal gland
Note: This is right isomerism. The adrenals are fused (horseshoe) and there is no spleen, just a large midline kidney).
Trilled lungs bilaterally, horizontal midline liver, asplenia… What would the adrenal gland look like?
Horseshoe adrenal gland
Note: This is right isomerism (normal left-sided structures messed up: e.g. spleen absent).
Think adrenal cyst
Note: These are developmental anomalies and are almost always benign, but are usually resected anyway because you can’t differentiate between this and cystic neuroblastoma.
Most common appearance of an adrenal neuroblastoma
Enlarged adrenal gland with hyperechoic component (may also have complex cystic appearance)
Adrenal ultrasound in newborn
Adrenal neuroblastoma
Where do neuroblastoma usually arise from?
The adrenal medulla
Neonatal adrenal ultrasound, s/p prolonged delivery
Think adrenal hemorrhage, recommend serial ultrasounds or MRI to differentiate from adrenal neuroblastoma (which will not get smaller)
Risk factors for neonatal adrenal hemorrhage
- Breech birth
- Fetal distress
- Congenital syphilis
Young child with adrenal calcifications…
Think prior adrenal hemorrhage (often leaves some adrenal calcifications behind after resolving)
Which side is more commonly involved in adrenal hemorrhage?
Right side (75%)
How can you differentiate adrenal hemorrhage from adrenal neuroblastoma?
Serial ultrasounds
Note: You could also do an MRI, but this is more expensive and requires sedation.
MVC
Traumatic adrenal hemorrhage
Waterhouse-Friderichsen syndrome
Note: Meningitis and adrenal hemorrhage.
Think adrenal hyperplasia
Note: Enlarged adrenal gland with cerebriform/lobulated contour. Most say that an adrenal gland larger than 20 mm is hyperplastic, but probably safe to assume if the test shows you an adrenal gland with calipers on it its probably hyper plastic.
Congenital adrenal hyperplasia with adrenal rests in the bilateral testes
What is the most common cause of congenital adrenal hypertrophy?
21-Hydroxylase deficiency (90% of cases)
Clinical manifestations of 21-hydroxylase deficency
- Genital ambiguity (females)
- Life threatening salt losing pathology (males)
Genital ambiguity in a female…
Think congenital adrenal hyperplasia secondary to 21-hydroxylase deficiency
Cushing disease
An overproduction of ACTH by a pituitary adenoma, resulting in too much cortisol and leading to Cushing syndrome
What is the most common cause of excess cortisol?
Cushing disease (ACTH-producing pituitary adenoma)
Wide “moon face”, buffalo hump, and purple skin striae…
Think Cushing syndrome
Common causes of Cushing syndrome
- Cushing disease: ACTH-producing pituitary adenoma (75%)
- ACTH-producing small cell lung cancer
- Cortisol-producing adrenal adenoma
- Primary adrenal hyperplasia
- Chronic high dose steroids
Think infradiaphragmatic extralobar pulmonary sequestration
Note: Direct blood supply from the aorta.
History of respiratory distress and cyanosis as a neonate
Think infra diaphragmatic extralobar pulmonary sequestration (given history)
Note: This can look exactly like an adrenal mass. Look for history of neonatal respiratory distress or a direct arterial blood supply from the aorta.
Diagnostic criteria for adrenal adenoma on noncontrast CT
HU < 10
Diagnostic criteria for adrenal adenoma on multiphase contrast enhanced CT
- Absolute washout > 60%
- Relative washout > 40%
AND
HU < 120 on arterial or portal venous phase imaging
How do you calculate absolute washout for an adrenal adenoma?
(enhanced HU - delayed HU)/(enhanced HU - unenhanced HU)
Note: Greater than 0.6 (60%) is diagnostic for adrenal adenoma.
How do you calculate relative washout for an adrenal adenoma?
(enhanced HU - delayed HU)/(enhanced HU)
Note: Greater than 0.4 (40%) is diagnostic for adrenal adenoma.
What other masses can mimic adenoma washout (you diagnose adrenal adenoma on multiphase CT, but are wrong)?
Hypervascular metastases (most commonly renal cancer, but also HCC) and pheochromocytoma
Adrenal mass has a relative washout of 50%…
Adrenal adenoma (diagnostic)
Adrenal mass has portal venous HU of 150 and a relative washout of 50%…
Think hypervascular adrenal metastasis (most commonly renal cancer) or pheochromocytoma
Note: If portal venous phase HU is greater than 120, think metastases (even if absolute/relative washout is diagnostic for adrenal adenoma).
Diagnostic criteria for adrenal adenoma on MRI
Microscopic fat (signal dropout between in and out of phase imaging)
What is the most common adrenal tumor?
Adrenal adenoma
Note: Up to 8% of the normal population has one.
What else should you look at even if multiphase contrast enhanced CT shows relative/absolute washout diagnostic for adrenal adenoma?
HU on arterial or portal venous phase imaging
Note: If > 120, do NOT call it an adenoma. It is more likely a hypervascular metastasis (usually renal cancer) or a pheochromocytoma.
What are the major types of adrenal adenoma based on function?
- Nonfunctioning (most common)
- Cortisol producing (Cushing syndrome)
- Aldosterone producing (Conn syndrome)
Think adrenal myelolipoma
Note: Large adrenal lesion with macroscopic fat.
What characteristics should make you think an adrenal mass is not an adrenal adenoma?
- Heterogeneity (hemorrhage, calcifications, necrosis)
- Arterial or portal venous HU > 120 (even if relative/absolute washout is diagnostic for adrenal adenoma)
- Large size (> 3 cm)
- Elevated serum/urine catecholamines
Adrenal mass and elevated catecholamines…
Pheochromocytoma
Bilateral small adrenal masses…
Think adrenal adenomas
Bilateral large adrenal masses…
Think pheochromocytoma or metastases (e.g. lung cancer)
Adrenal mass with portal venous HU 140…
Think hypervascular met (e.g. renal cancer, HCC) or pheochromocytoma
Note: Anything over 120 HU on arterial or portal venous phase should make you think these rather than an adenoma.
Think adrenal collision tumor (two different tumors smashed together, usually one is an adenoma) and recommend MRI or FDG PET/CT
Note: Hypodense adrenal mass with hyperdense nodular components.
Conn’s syndrome
A syndrome of excessive aldosterone production (usually due to an aldosterone-producing adrenal adenoma)
What is the classic imaging appearance of a pheochromocytoma?
- Heterogeneous adrenal mass with AVID enhancement
- T2 bright
Which nuclear imaging studies are best to diagnose pheochromocytoma?
- MIBG (best)
- Octreotide (not as good because there is uptake in the kidneys, which may obscure adrenal masses)
Think hypervascular metastasis (renal cell > HCC) or pheochromocytoma
Note: HU should never get > 120 for an adrenal adenoma.
Consider extra-adrenal pheochromocytoma (in the organ of Zuckerandl often at the inferior mesenteric artery)
Rule of 10s for pheochromocytoma
- 10% are extra adrenal (usually organ of Zuckerkandl near IMA)
- 10% are bilateral
- 10% are in children
- 10% are hereditary
- 10% are not active (90% have hypertension)
Pheochromocytomas are associated with which syndromes?
- Von Hippel Lindau
- MEN IIa
- MEN IIb
Note: Also associated with NF-1, Sturge Weber, and Tuberous sclerosis.
What percentage of pts with MEN II have pheochromocytomas?
50%
Note: Both MEN IIa and IIb get pheochromocytomas, usually multiple and bilateral.
Adrenal mass in a pt with MEN II…
Pheochromocytoma
Carney triad
- Extra-adrenal pheochromocytoma
- GIST
- Pulmonary hamartoma/chondroma
Note: Do not confuse this with Carney complex (cardiac myxoma and skin pigmentation).
Classic imaging appearance of an adrenal myelolipoma
Adrenal mass with macroscopic fat
Note: 25% have calcifications.
Major complication of adrenal myelolipoma
Retroperitoneal hemorrhage (they can bleed if they get large, usually > 4 cm)
Adrenal myelolipomas are associated with what syndromes?
Endocrine syndromes (Cushings, Congenital adrenal hyperplasia, Conns)
Note: The myelolipoma isn’t causing these syndromes (myelolipomas are not functional), it’s just associated with these things in 5-10% of cases.
Think myelolipoma
Note: The diaphragm appears discontinuous on ultrasound due to the macroscopic fat in the adrenal myelolipoma (caused by speed displacement artifact because sound waves travel slower in fat).
What are the most common primary cancers to metastasize to the adrenal gland?
- Breast cancer
- Lung cancer
- Melanoma
Note: If the adrenal mass is hypervacular, think renal cancer or HCC met (or primary pheochromocytoma).
Think adrenal cyst
Note: If large, these can bleed.
Differential for adrenal calcifications
- Prior trauma/hemorrhage
- Prior infection (e.g. tuberculosis)
- Certain tumors (cortical carcinoma, neuroblastoma, myelolipoma, melanoma metastases)
Differential for adrenal calcifications
- Prior trauma/hemorrhage
- Prior infection (e.g. tuberculosis)
- Certain tumors (cortical carcinoma, neuroblastoma, myelolipoma, melanoma metastases)
Which adrenal tumors often calcify?
- Cortical carcinoma
- Neuroblastoma
- Myelolipoma
- Melanoma metastases
Wolman disease (bilateral enlarged and calcified adrenal glands)
Wolman disease (bilateral enlarged and calcified adrenal glands)
Wolman disease
An inborn error of fat metabolism that results in bilateral enlarged and calcified adrenal glands
Note: This is fatal within the first year of life.
Classic imaging features of adrenal cortical carcinoma
Large (> 5 cm), nasty looking adrenal mass with central necrosis
Note: 20% have calcifications.
60% of adrenal cortical carcinomas are functional, presenting with…
Cushings syndrome (due to cortisol production)
Cushings syndrome (moon face, striae, buffalo hump)
Adrenal cortical carcinoma
Adrenal cortical carcinoma
Note: Diffusion bright adrenal mass with heterogeneous progressive enhancement.
Cushings syndrome
Adrenal cortical carcinoma
Note: Large adrenal mass with heterogeneous enhancement (including capsular enhancement) and central necrosis.