D/D of Adrenal Masses :
· Smooth contour and well marginated, diameter less than 5 cm.
· May appear heterogeneous due to cystic degeneration or hemorrhage.
· If a functioning adenoma, may have report of hypersecretion of cortisol (Cushing’s syndrome), aldosterone (Conn’s syndrome), or androgens (adrenal virilization). Correlate clinically.
· Unilateral mass with decrease in size of contralateral gland.
· Usually 2-4 cm diameter lesion.
Hypoattenuating lesion in gland with average diameter less than 2 cm (need thinner cuts to visualize).
o Have diffuse enlargement bilaterally.
o A variant called macronodular hyperplasia shows not only thickened adrenals but multiple nodules.
o Clinically will have hyperfunctioning gland.
o Size is often greater than 5 cm with central areas of necrosis, may have tumor calcification.
o Tumor may demonstrate spread into the lever, nodal system or venous system.
o The adrenals are the fourth most common location for metastatic disease. In most cases, patients are asymptomatic.
o Appearance on CT is widely variable, but there are five patterns commonly seen :
o Mass less than 5 cm in diameter.
o Mass greater than 5 cm in diameter.
o Multiple masses.
o Diffuse enlargement.
o Normal appearing glands.
o It is frequently difficult to distinguish a nonhyperfunctioning adenoma from a metastasis in cancer patients.
o In non-cancer patients, an adrenal mass less than 5 cm in size with no features consistent with malignancy should be followed with serial CT scans. If after 18 months the lesion is stable, it can be considered benign.
· Typically greater than 3 cm, and if large, may be cystic due to necrosis.
· Because of hypervascular nature, will enhance brightly with contrast.
· May contain calcification.
· Clinically will have hyperfunction, with increased urinary levels of catecholamines.
· If associated with MEN syndrome or von Hippel-Lindau disease, may have lesions in pancreas, kidney and spinal cord.
· If difficult to differentiate from adenoma, perform T2-weighted MR. Pheochromocytoma will have significantly higher signal intensity.
· Round to oval adrenal mass.
· In adults, is typically related to blunt abdominal trauma, and if so is usually right sided.
· Acute to subacute hematomas have attenuation values between 50 and 90 HU. Follow up studies will demonstrate decrease in size and attenuation.
· Unilateral and solitary hypoattenuating mass.
· Usually round or ovoid with thin, smooth wall.
· Inferior wall may be flat or even concave.
· May see peripheral, curvilinear calcification.
· Granulomatous infection
o The most common infectious cause of Addison disease is tuberculosis.
o Early adrenal findings include bilateral enlargement with a hypoattenuated center & an enhancing rim. Later the adrenal atrophies with calcification
o With disseminated histoplasmosis, CT demonstrates bilateral enlargement again with central hypoattenuation and a peripheral rim. Diagnosis can be made with FNA biopsy and special staining.
· Pneumocysitis carinii infection
o Consider in immunocompromised patient population.
o On unenhanced CT will see either punctate or coarse calcifications in multiple abdominal structures including the adrenals, liver, spleen, kidneys and lymph nodes.
o Most adrenal abscesses are found in neonates who have had a prior adrenal hemorrhage.
o On contrast-enhanced CT will see thick-walled cystic mass.
· Usually asymptomatic unless hemorrhage within the mass causes symptoms.
· Consist of mature fat and bone marrow. Appearance ranges from nonfatty soft tissue mass to a fat predominated mass. Typically unilateral, may be calcified, especially if had previous hemorrhage.
· Most commonly has a well-defined capsule surrounding fat. Attenuation ranges especially if had previous hemorrhage.
· With contrast, the soft-tissue areas will enhance, potentially masking the areas of fat.
· Rare benign tumor that is a well-defined hypoattenuating or heterogeneously attenuating mass, often containing calcifications.
· A characteristic finding is phleboliths within the haemangioma.
· Homogeneous hypoattenuating lesions in comparison to muscle on both enhanced and unenhanced CT, may have calcification.
· CT-guided biopsy or surgical resection necessary to confirm diagnosis.