Approach to Adrenal Mass

What is incidentaloma

Mass >1cm detected on imaging WITHOUT suspected adrenal disease

Algorithm for incidentaloma

Found mass → Screen for hormone excess → If positive → Confirm test → Unilateral adrenalectomy; repeat imaging if hormone negative with sign of CA

Diagnostic criteria for lipid rich adenoma

Density <=10 HU; should see low attenuation on unenhanced CT

What percent of adenoma are lipid rich

70%; most adrenal tumors are non hyperfunctioning

Incidental mass > 1cm needs what signs to be benign

Lipid rich adenoma, myelolipoma, cyst, benign calcification

Mass 1-4cm with NCCT >10 HU + wash out and signal drop indicate what

Lipid poor adenoma; if >4cm likely to be adenoma

Mass 1-4cm with NCCT >10 HU + NO wash out and signal drop indicate what

Pheochromocytoma, adrenal cortical carcinoma, metastasis, lipid poor adenoma → Do more imaging

What is myelolipoma

Benign tumor made of bone marrow element; has area with fat < 10 HU

What are adrenal cyst

Water density with no enhancement (0-10 HU), thin wall thin septa

When can benign calcification be found in adrenal imaging

Adenoma, myelolipoma, post trauma, granulomatous infection

Absolute wash out formula

(Enhanced CT HU - Delayed CT HU)/(Enhanced CT HU - Unenhanced CT HU) x100

Relative wash out formula

(Enhanced CT HU - Delayed CT HU)/Enhanced CT HU x 100

Washout percentages that indicate adenoma

Absolute >=60%, relative >=40%

What are adrenocortical carcinoma

60% are functioning → Present as Cushing syndrome or mixed with virilization syndrome; associated with MEN1, Lynch, Beckwith-Wiedemann and Li Fraumeni

Characteristic of adrenocortical adenoma

Bulky, irregularly shaped; >6cm at diagnosis, areas of necrosis, hemorrhage and calcification

What are pheochromocytomas

In adrenal medulla, >10 HU in unenhanced, high enhancement with delayed washout

What is I-131 MIBG

NE analog; imaging and treatment of neuroendocrine tumors like neuroblastoma, paraganglioma, and pheochromocytomas

What is 18-F DOPA and DA

Pheochromocytoma specific compound used in PET/CT imaging