Granulomatous Infection (Tuberculosis) is the most common infectious cause of Addison disease. CT appearance of granulomatous infection depends on the time and activity of the inflammatory process. 

• early-stage “adrenalitis” includes bilateral adrenal enlargement with a central necrotic area of hypoattenuation and a peripheral enhancing rim
• In the healing stage of the disease, the adrenal glands become calcified and atrophic (adrenal calcification)

Addison disease may be either acute, subacute, or chronic:

• acute Addison disease occurs within a few weeks to months and is caused by bilateral adrenal hemorrhage (adrenal apoplexy), secondary to shock and sepsis or trauma. On CT scan bilateral adrenal hematomas are demonstrated
• subacute disease (adrenalitis): when the disease has been present for less than 2 years. On CT enlargement of both adrenal glands, with necrotic centers and a rim of contrast enhancement are usually demonstrated. A CT-guided biopsy helps to identify the cause such as tuberculosis, histoplasmosis, and other fungi
• chronic disease: may be caused by a chronic autoimmune disorder, chronic granulomatous infection (TB or histoplasmosis). On CT both adrenal glands appear small and atrophic with associated with calcifications in granulomatous adrenalitis