see also:

• renal malignancies
• neoplasia / cancer / tumours

• 0.6-1.3% of CT scans of the abdomen reveal an incidental adrenal mass - the incidentaloma
• adrenal masses are present on autopsy of 1.4-9% of people who were not known to have adrenal disease with a rate of 2% in younger adults, rising to 8-10% in the elderly

• lipoma
• myelolipoma
• cysts

• adrenal adenomata
  • usually discrete homogeneous lesions with smooth, regular, encapsulated borders
  • typically have low attenuation values of ≤10 Hounsfield units but 1% of malignant lesions will fall in this attenuation zone
  • CT scans cannot reliably distinguish:
    • hyperfunctioning vs nonfunctioning
    • benign vs malignant
  • aldosteronoma:
    • 2% of adrenal masses
    • hyperfunctioning tumour which secretes aldosterone and is the main cause of primary hyperaldosteronism (70-80% of cases) which presents as hypertension +/- hypokalaemia (hypokalaemia may not occur if patient is on a low sodium diet)
    • has a speckled appearance
    • measure plasma aldosterone concentration and plasma renin activity (after the patient has been upright for at least 2 hours) and determine the ratio
  • cortisol-producing adenoma:
    • 2-15% of adrenal masses
    • causes 20% of cases of Cushing's syndrome
    • a low-dose dexamethasone suppression test is a good screening tool
  • phaeochromocytoma:
    • often evident from clinical picture:
      • episodic hypertension, headache, sweating, palpitations, anxiety, pallor and tremors
      • may be associated with endocrine syndromes such as:
        • neurofibromatosis
        • von Hippel-Lindau disease (retinal angiomas)
        • multiple endocrine neoplasm II (medullary thyroid carcinoma)
    • ~10% of adrenal masses
    • easy to detect on MRI
    • diagnostic tests include:
      • plasma catecholamines (>2000 pg/mL) - lower levels may require further Ix such as a clonidine suppression test
      • 24hr urinary metanephrines >1.6 mg/24 hr
• adrenocortical carcinoma
  • rare - occur in approx. 1 in 2 million population
  • account for 1% of adrenal masses which are investigated, and perhaps 1 in 1500 of all adrenal masses found
  • look like adenomas when small but as they get bigger, usually become inhomogeneous with irregular borders, and may have local lymphadenopathy or local invasion evident (eg. into renal vein or IVC)
  • typically have a higher attenuation values of >18 Hounsfield units but 15% of adenomas fall into this attenuation zone
• metastatic cancer
  • account for up 21% of adrenal masses
  • most common primaries are: breast cancer, lung cancer, renal malignancies, multiple myeloma, lymphoma
• adrenal hyperplasia:
  • often bilateral and a cause of Cushing syndrome
• tuberculosis (TB)

• partly based upon:
  • Proc (Bayl Univ Med Cent). Jan 2003; 16(1): 7–12.
  • https://www.racgp.org.au/afp/2017/june/incidental-adrenal-masses-a-primary-care-approach/
  • Guidelines for the management of the incidentally discovered adrenal mass 2011

• MRI performs better than CT scan in distinguishing benign vs malignant and shows pheochromocytoma well

• 24hr urine catecholamines and metanephrines to help excl. phaeochromocytoma or carcinoma
• dexamethasone suppression test
  • screen: 1 mg overnight dexamethasone suppression test
  • confirmation:
    • 8 mg dexamethasone suppression test
    • Midnight salivary cortisol
• if hypertension, plasma aldosterone:renin ratio
• clinical features which may result from hyperfunctioning tumours:
  • Cushings syndrome
    • Moon face, acne, buffalo hump, supraclavicular fat-pads, central obesity, striae, easy bruising, poor wound-healing, emotional and cognitive changes, hypertension, hyperglycaemia, hyperlipidaemia, osteoporosis
  • Conn's syndrome:
    • Refractory hypertension, hypokalaemia, muscle cramps, headaches, palpitations, polydipsia, polyuria
  • phaeochromocytoma:
    • Palpitations, flushing, sweating, headache, tremor, anxiety, LOW, severe hypertension
  • Adrenocortical carcinoma
    • severe hypertension, LOW, Palpitations, flushing, sweating, headache, tremor, anxiety, hirsuitism, gynaecomastia, amenorrhoea, infertility, mass effect, metastatic

• adrenal scintigraphy such as MIBG scans can help distinguish hyperfunctioning vs nonfunctioning, as well as find extra-renal disease but are not readily available and are expensive
  • up to 89% sens and 88-100% spec. for detecting phaeochromocytoma

• surgical excision unless aged > 40yrs, unfit for surgery and asymptomatic in which case consider medical Mx

• if > 4cm or has a malignant appearance

• important to first exclude pheochromocytoma to prevent a hypertensive crisis
• usually reserved for patients with known extraadrenal malignancy when tissue diagnosis of the adrenal metastasis is necessary to guide therapy

• consider repeat imaging in 3-12 months if > 1cm diameter