- Adrenal Mass Discovered Incidentally on Non-Contrast CT
- HU < 10 benign
- HU > 10 indeterminant
- Contrast enhanced CT or MRI
- Adrenal Mass Discovered Incidentally on Contrast CT
- Obtain Delayed Images (15 minutes), if HU < 24 benign
- Calculate RPW, if >40% then benign, if above, consider biopsy or PET
Adrenal Lesion Characterization Calculator at www.chestxray.com.
Benign Adrenocortical Adenoma - round, sharp margins, can be lipid rich or lipid poor.
- CT - HU <10 (non contrast), rapid wash in and wash out, (non-adenomas have a more intense initial enhancement and a delayed washout.)
- MRI - chemical shift (signal dropout on out of phase imaging) because of intracellular lipid and water in same voxel compared to the in phase image.
- CT - HU>20, intense and persistent enhancement
- MRI - low T1 (or high if hemorrhagic), moderately hyperintense T2, delayed washout, no chemical shift
Adrenocortical Carcinoma - 10% clinically functional, large and aggressive
Myelolipoma - no malignant potential, macroscopic fat density lesions
- CT - acute to subacute HU 50-90 with surrounding stranding
- Acute (<7 days) - iso or hypo T1, marked hypo T2, high intracellualr deoxyhemoglobin
- Subacute (7 - 60 days) - hyperintense on T1 and T2, free methemoglobin (high T1)
- Chronic (2- months) - bloom on GRE, hypointense rim on T1 and T2 (hemosiderin)
Adrenal Cysts - Fluid density, recc follow-up to exclude cystic neoplasm
Infection - fungal or TB
Hemangiomas, Ganlioneuromas, Angiosarcomas, Melanomas
Multiple Endocrime Neoplasia
- MEN Type I - cortical nodules or adenomas, rarely functional
- Associated with: parathyroid hyperplasia, gastrinoma, insulinoma, vipoma and glucagonoma, anterior pituitary tumors (prolactinomas, growth hormone or ACTH), carcinoid tumors, lipomas and thyroid nodules.
- MEN Type IIA and IIB - pheochromocytomas in adrenal medulla
- Associated with: medullary thyroid cancer, neuromas, ganglioneuromatosis, marfan like build
Conn's Syndrome - aka primary hyperaldosteronism, clinical hypertension and hypokalemia
- Aldosterone secreting adenoma - 60%, less than 2cm, F>M, contains lipid laden cells, treated surgically
- Adrenal hyperplasia - 40%, nodular thickening, treated medically
- Functioning adrenocortical carcinomas - very rare
Cushing's Syndrome - chronic excess glucocorticoids, clinical obesity, plethora, bruising, striae, muscle wasting, osteoporosis, diabetes.
- ACTH Dependent - 80%, pituitary hypersecretin of ACTH (Cushing's Disease) or ectoptic ACTH secretion, causes adrenal hyperplasia
- ACTH Independent - 20%, adrenal adenoma and adrenocortical carcinoma
Adrenogenital Syndrome - excessive secretion of sex hormones with clinical symptoms reflecting time and hormone secreted.
Pheocromocytoma - tumor of the chromaffin cells in the medulla, release epi and norepi, clinical headaches, palpitations, sweating, tremor, anxiety, hypertension.
- Rule of Tens - 10% multicentric, bilateral, malignant, extra-adrenal
- CT - enhancing lesions, often with calcification and necrosis
- MRI - T1 isointense, T2 hyperintense, enhancing mass
- MIBG - analog of norepi, avid uptake
Addison's Disease - adrenal cortical hypofunction, clinical lethargy, fatigue, weakness, anorexia, weight loss, abdominal pain, hypotension
- Causes - autoimmune, infection, drugs, hemorrhage, mets, sarcoid, hemochromatosis, amyloid
- Small calcified adrenal glands
- Cortisol producing adenomas suppress ACTH levels resulting in atrophy of the remaining gland.
- Adrenal Hyperplasia can be primary (Conn's) or response to ACTH (Cushing's).