Adrenal Gland Flashcards
USF of adrenal haemorrhage
Best diagnostic clue: Hyperechoic well-defined lesion within adrenal gland
• Unilateral or bilateral adrenal hematomas
• AH appears as round or oval, well-defined adrenal mass with variable echogenicity depending on the stage of hemorrhage
• Acute hematoma: Hyperechoic
• Subacute hematoma: Mixed echogenicity ± central hypoechoic area
• Chronic hematoma: Anechoic & cyst-like lesion; ± curvilinear/eggshell calcification
• Asymmetric enlargement of adrenal glands
• ±Peri-adrenal hemorrhage ± perinephric extension
• Displacement & mass effect on kidney & IVC
Hyperechoic hemorrhage within pre-existing adrenal mass
• Avascular hematoma on color Doppler
• ±Associated renal vein thrombosis
• ±Extension of thrombus into IVC
• Secondary adrenal hemorrhage; variable vascularity of underlying adrenal tumor
• US for initial screening & detection followed by CT/MR for further characterization
• Left adrenal gland can be difficult to see on US& small lesions may be obscured
Checklist for adrenal haemorrhage
• Check for history of trauma, anticoagulant therapy, coagulopathies, malignancies, stress, adrenal tumor
• US; hyperechoic avascular lesion within adrenal gland with relevant clinical features
• MR: Signal intensity varies with age of hematoma
USF of myelolipoma
Best diagnostic clue: Heterogeneous fatty adrenal mass
• Well-defined, homogeneous, echogenic mass (when predominantly composed of fatty tissue)
• When small difficult to distinguish from the echogenic retro-peritoneal fat
• “Apparent diaphragm disruption”: Propagation speed artifact; decreased sound velocity through a fatty mass leads to this appearance, usually seen when tumor> 4 cm
• Heterogeneous mass (when myeloid cells predominate), may be isoechoic or hypoechoic
Heterogeneous echo pattern may also be due to internal hemorrhage (common), ± calcification
• When large & atypical: Ultrasound-guided FNAC can be performed to confirm diagnosis
• Color Doppler: Avascular to hypovascular adrenal mass
Checklist for myelolipoma
Differentiate from other tumors (lipid-rich adenoma)
USF of adrenal cysts
Best diagnostic clue: Well-defined, hypo or anechoic adrenal mass ± calcification
• Unilocular/multilocular, well-defined, adrenal mass
• Round or oval with thin smooth wall
• Posterior acoustic enhancement
• Occasionally with internal debris (hemorrhage) and septation
• Calcification (15%); variable in shape and location
Complicated cyst; ~ 5 cm size, internal echoes with septation or thick wall (~ 3 mm), t malignant potential
• Ultrasound-guided percutaneous cyst aspiration; ± injection of sclerosing agent
USF of pheochromocytoma
Remembered as “10% tumors” or “rule of 10s”
• 10% extra-adrenal: Paragangliomas/chemodectomas
• 10% bilateral
• 10% malignant
• 10% familial, pediatric, silent
• 10% have autosomal dominant transmission & associated with various other dominant conditions
• Variable appearance; purely solid (68%), complex (16%) & cystic tumor (16%)
• Small tumors typically solid, round & well-circumscribed masses, with uniform echogenicity
Large tumors may appear as purely solid masses with homogeneous (46%) or heterogeneous (54%) echo pattern
• Calcification is seen in 10% of pheochromocytomas
• Always evaluate bladder wall, renal hilum & organ of Zuckerkandl at origin of IMA
• Hypervascular on color Doppler
USF of adrenal carcinoma
Best diagnostic clue: Large, solid, unilateral adrenal mass with invasive margins (bilateral in 10%)
• Functioning tumors: Usually ~ 5 cm at presentation
• Nonfunctioning tumors: 10 cm or more
• Variable appearance depending on size & contents, ± calcification
• Small tumors: Echo pattern similar to renal cortex
• Large tumors: Mixed heterogeneous echo pattern with hypoechoic/anechoic areas (due to necrosis & hemorrhage)
• Metastasis to regional & periaortic lymph nodes (reliable sign of malignancy)
• Differentiation between adrenal carcinoma, adrenal adenoma & neuroblastoma may not be possible by ultrasound
Color Doppler: Invasion/occlusion of adrenal vein, renal vein & IVC; visualization of intraluminal tumor thrombus ± vascularity
• Best imaging tool: US for initial screening followed by CT/MR for further characterization, evaluating the tumor extent, vascular invasion & distant metastasis
Diagnostic checklist for adrenal carcinoma
Large to medium sized, unilateral adrenal mass with calcification & invasive margins + venous + nodal or distant metastases: Highly suggestive of adrenal carcinoma
