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60 years old female with history of breast cancer presents for ultrasound evaluation of RUQ pain.

Adrenal Mass Differential Diagnosis:
 

Adrenal Cortex:

• Adenoma
• Nodular Hyperplasia
• Carcinoma
• drenal Medulla:
• Pheochromocytoma
• Ganglioneuroma
• Ganglioneuroblastoma

Metastates:

• Breast, Lung, Lymphoma
• Leukemia, other

Technical Artifacts:

Other:

• Myelolipoma
• Neurofibroma
• Hamartoma
• Teratoma
• Xanthomatosis
• Amyloidosis
• Cyst
• Hematoma
• Granulomatosis

Pseudoadrenal:

• Renal, Pancreas, Spleen etc

• Incidence: 25% at autopsy.

• Most common sites: lung, breast, kidney, bowel, ovary, melanoma.

• Radiographic features: adrenal mass, bilateral masses, heterogeneous enhancement, indistinct, irregular margins. Signal intensity on MRI is similar to that of spleen on T1W and T2W images. However there is considerable overlap in Sl between mets and adenomas; the typical adenoma has an Sl similar to that of adrenal tissue on T1W and T2W images.

• CT biopsy usually performed in equivocal cases.

Approach to Adrenal Masses:

• Adrenal masses are best evaluated first by noncontrasted CT.
• Masses with HU < or equal to 10 considered to be adenpmas.
• If HU >10, the mass is considered indeterminate and an enhanced and 15 minute delayed CT scan is obtained. If the enhancement washout is more than 50%, especially if the delayed attenuation value is less than 35 HU, a diagnosis of lipid-poor adenoma is made with no further evaluation.
• if enhancement is less than 50%, especially if the delayed attenuation is >35 HU, the mass is considered indeterminate. Percutaneous biopsy considered.
• Using 10 HU as scut-off for diagnosis, the test has a sensitivity of 71% and a specificity of 98%.
• 30% of adenomas have an attenuation of more than 10 HU and are indistinguishable from other masses.
• If an adrenal mass is detected on a CECT a 15 minute delayed scan should be obtained to evaluate.
• Chemical shift MR imaging can be used to characterize lipid-rich adenomas with accuracy similar to that of nonenhanced CT. adenomas with only a small amount of lipid will not be detected.

Adrenal Masses, Ddx:

Small Solid Adrenal Nodule:

• Adenoma
• Metastasis
• Pheochromocytoma
• Granulomatous Disease
• Myelolipoma
• Complex Cyst

Large Solid Adrenal Nodule:

• Pheochromocytoma
• Metastasis
• Hemorrhage
• Hemangioma
• Neuroblastoma/Ganglioneuroma

Bilateral Large Adrenals:

• Hyperplasia
• Metastases
• Hemorrhage
• Granulomatous Disease
• Lymphoma