Adrenocorticotropin independent macronodular adrenocortical hyperplasia
Adrenocorticotropin independent macronodular adrenocortical hyperplasia (AIMAH) is considered a rare form of macronodular adrenal hyperplasia. It is an uncommon cause of primary adrenal hypercortisolism.
Patients with AIMAH tend to present 10 years earlier on average than the time of presentation of classic Cushing disease. The age of presentation usually ranges around 40-50 years. Their symptoms also tend to be milder than that of typical Cushing disease.
While the exact pathology is obscure, it is generally thought to result from aberrant hormone receptor signalling.
CT often characteristically shows massively enlarged multinodular adrenal glands. The nodules tend to vary in size ranging between 1 and 5.5 cm and are generally hypo-attenuating 3. There is also often distortion of the adrenal contour.
Signal characteristics of the glands as well as the nodules tend to be 2-3
- T1: generally hypointense compared with the liver
- T2: hyperintense compared with the liver
- in-out phase imaging: nodules usually lose signal on out of phase imaging due to chemical shift from high intrinsic lipid content
- 1. Gourtsoyiannis N. Clinical MRI of the Abdomen, Why, How, When. Springer Verlag. (2011) ISBN:3540856889. Read it at Google Books - Find it at Amazon
- 2. Doppman JL, Chrousos GP, Papanicolaou DA et-al. Adrenocorticotropin-independent macronodular adrenal hyperplasia: an uncommon cause of primary adrenal hypercortisolism. Radiology. 2000;216 (3): 797-802. Radiology (full text) - Pubmed citation
- 3. Gourtsoyiannis N. Clinical MRI of the Abdomen, Why, How, When. Springer Verlag. (2011) ISBN:3540856889. Read it at Google Books - Find it at Amazon