Primary pigmented nodular adrenal dysplasia (PPNAD) is a rare benign adrenal condition characterized by ACTH-independent autonomous hypersecretion of cortisol, leading to Cushing syndrome.
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Epidemiology
PPNAD is often familial. Patients typically present as children or young adults, and there is a female predilection 1.
Associations
PPNAD is associated with Carney complex, which is sometimes the reason for diagnosis.
Clinical presentation
Presentation is usually with Cushing syndrome, which is often relatively mild, on account of cortisol levels being only mildly elevated, and thus often not recognized from many years 1.
Pathology
Genetics
Multiple gene mutations have been implicated, the most common of which is a mutation in the PRKAR1A gene, which is inherited in an autosomal dominant pattern 2.
Radiographic features
The adrenal glands are not significantly enlarged, but contain multiple bilateral nodules, typically 2-5 mm in diameter, although in older patients they may be as large as 1-2 cm 1. The intervening 'normal' gland appears atrophic.
CT
The nodules range in density from isodense to the rest of the adrenal gland, to somewhat hyperdense.
MRI
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T1
lower signal intensity than surrounding atrophic adrenal tissue
signal drop out demonstrated on out-of-phase imaging
T2: lower signal intensity than surrounding atrophic adrenal tissue
Treatment and prognosis
The treatment of choice is bilateral adrenalectomy.
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