Adrenal Glands Flashcards
1
Q
Normal Adrenal Glands Anatomy
A
- Outer cortex: Steroid hormones (cortisol, aldosterone, androgens and estrogens).
- Medulla: Catecholamines (epinephrine and norepinephrine).
- <10 mm in thickness.
- CT attenuation about equal to muscle on precontrast scan.
2
Q
CT protocol for Adrenal Lesions
A
- Non-contrast
- Enhanced phase: 60 secs
- Delayed phase: 15 mins
3
Q
Adrenal Myelolipoma
A
- Uncommon benign adrenal tumor with no malignant potential.
- Asymptomatic or spontaneous painful hemorrage.
- Mature fat (-74 HU) and interspersed hematopoietic bone marrow elements (20-30 UH).
- Hemorrage appears as foci of high attenuation within the fatty mass.
- Small calcifications may be present (24%).
- Size 1-17 cm.
- > 7 cm increases risk of hemorrage (surgical removal is recommended).
- Extra-adrenal locations: presacral space and retroperitoneum and other locations (mediastinium, abdomen and muscle fascia).
4
Q
Adrenal Cysts
A
- Asymptomatic, incidental.
- Well marginated, thin-walled (<3 mm), non-enhancing, homogeneous, fluid-filled masses (<20 HU).
- Thin internal septations are sometimes present.
- Hemorrage: May produce peripheral calcifications and pseudocysts.
- Up to 20 cm in size.
5
Q
Adrenal Pseudocysts
A
- 40% of adrenal cysts, due to sequela of hemorrage.
- Fibrous walls without a cellular lining.
- Cyst contents are usually of higher attenuation than simple fluid, still no enhancement.
- Calcification in the wall is commonly present (56%).
6
Q
Adrenal Hemorrage
A
- Newborn: due to hypoxia, birth trauma, or septicemia.
- Children and Adults: Blunt abdominal trauma, coagulopathy or underlying tumor.
- CT: Round or oval hyperdense (50-90 HU) mass + Fat periadrenal stranding.
- Predisposition to be unilateral on the right side.
- Evolution of the blood clot makes the mass shrink and decrease in attenuation + Calcifications.
- Chronic changes might be difficult to differentiate from other adrenal masses.
7
Q
Adrenal Pseudolesions
A
- Non-adrenal structures that may simulate an adrenal mass.
- Much more common on the left side.
- Unopacified portions of the stomach or small bowel: Identified by oral contrast CT.
- Tortous blood vessels: Identified by contrasted CT or doppler US.
- Accesory spleen or splenic lobulation: CT attenuation and enhancement identical to splenic tissue.
8
Q
Adrenocortical Carcinoma
A
- Very rare, affects people 30-70 years old.
- Associated with adrenal hyperfunction in 50% of cases.
- Symptoms: Cushing syndrome, abdominal pain or abdominal mass.
- Agressive, invasive and highly lethal.
- Usually large (>6 cm)
- CT: Unhanced CT > 10 HU, solid (may have fat), heterogeneous (necrosis, calcifications), malignant wash-out, usually replaces the gland.
- Bilateral in 10% of cases.
- Tumor thrombus in the renal vein or IVC is common (may generate a pulmonary embolus).
- DD: Large degenerated benign adrenal adenomas (Rare).
9
Q
Adrenal Lymphoma
A
- Primary lymphoma is extremely rare.
- Usually secondary: 4% of patients with non-Hodgkin lymphoma.
- Most common: Encasement of the adrenal gland by a retroperitoneal adenopathy.
- Other presentations: Small discrete focal or multifocal mass and diffuse adrenal enlargement.
- Bilateral in 50% of cases.
- Malignant wash-out.
10
Q
Adrenal Calcifications Differential diagnosis (6)
A
- Adrenal hemorrage sequela.
- Tuberculosis.
- Histoplasmosis.
- Children: Neuroblastoma and ganglioneuroma.
- Adults: Adrenal tumors (Adrenal carcinoma, pheochromocytoma, ganglioneuroma and metastases).
11
Q
Adrenal Cortical Hyperplasia
A
- Associated with Cushing syndrome with excess secretion of ACTH.
- Adrenal glands enlarged but mantain their normal shape (Thickness >10 mm).
- Multinodular pattern may also occur, might mimic multiple small metastases.
- Biochemical hyperplasia may be associated with a normal adrenal gland size.
12
Q
Cushing Syndrome
A
- Symptoms: Wight gain, hypertension, acne, muscle weakness, diabetes and deposits of fatty tissue in face, back and neck.
- 70% bilateral hyperplasia, 20% benign hyperfunctioning adrenal adenoma, 10% adrenocortical carcinoma.
- May also be caused by iatrogenic administration of glucocorticoids and cushing disease.
13
Q
Cushing disease
A
- ACTH secreting pituitary adenoma, which stimulates the adrenal gland.
- MRI of the pituitary gland is often definitive in identifying the cause:
- Benign hyperfunctioning adenomas round or oval <2 cm.
- Hyperfunctioning adenomas are indistinguisable from non-hyperfunctioning adenomas.
- Adrenal hyperplasia is usually smooth, diffuse and bilateral.
14
Q
Conn Syndrome
A
- Primary hyperaldosteronism.
- 60% bilateral adrenal hyperplasia.
- 40% Benign hyperfunctioning adenoma.
- Causes: Hypertension with or without hyperkalemia.
- Rare: Adrenal carcinoma as a cause.
15
Q
Adrenogenital Syndrome
A
- Excess secretion of androgens.
- Congenital: Autosomal recessive enzyme deficit and bilateral adrenal hyperplasia.
- Acquired: 80% Hyperfunctioning adrenal adenoma, 20% adrenal cortical carcinoma.
