CT Findings of Primary Pigmented Nodular Adrenocortical Disease: Rare Cause of ACTH-Independent Cushing Syndrome

Abstract

AJR 2010; 194:W541 0361–803X/10/1946–W541 © American Roentgen Ray Society CT Findings of Primary Pigmented Nodular Adrenocortical Disease: Rare Cause of ACTH-Independent Cushing Syndrome We read with great interest the article by Johnson and colleagues [1], “Adrenal Imaging With MDCT: Nonneoplastic Disease,” in the October 2009 issue of the AJR. The authors make a thorough and detailed description of the spectrum of CT findings in nonneoplastic adrenal diseases, enriched with high-quality and representative figures. The authors mention that adrenocorticotropic hormone (ACTH)-independent Cushing syndrome (CS) due to either adrenal adenoma or carcinoma is a major cause of adrenal hyperplasia [1]. Primary pigmented nodular adrenocortical disease (PPNAD) also is associated with ACTH-independent CS, but it is characterized by smallto normal-sized adrenal glands containing multiple small cortical pigmented nodules or macronodules, most often surrounded by an atrophic cortex [2, 3]. PPNAD is seen mostly in infants, children, or young adults and is characterized by elevated levels of plasma and urinary cortisol that are not suppressed or may be increased by high doses of dexamethasone (Liddle test) [2]. The clinical presentation of CS in this group of patients may be atypical, with common manifestations including an asthenic body habitus, short stature, severe osteoporosis, and severe muscle and skin wasting [2]. Atrophy of the cortex in CS patients is characteristic of PPNAD and reflects the autonomous function of these nodules and suppressed levels of pituitary ACTH [2–4]. Despite their small size—usually less than 6 mm—the nodules are visible at CT, and their visualization is facilitated by the surrounding cortical atrophy [3]. These two factors (i.e., atrophy and nodules) create an irregular contour of the gland (Fig. 1). This irregularity is distinctly abnormal and diagnostic for the disease, especially in younger patients [3]. The characteristic pigments—within the nodules or the adrenal limbs—contain lipofuscin, which may become partly melanized, forming neuromelanin and appearing at CT as hypodense dots a few mm in diameter (Fig. 1). The possibility of PPNAD should arise in young patients with classic CS or with atypical, subclinical, or cyclic hypercortisolism and adrenal glands of normal or reduced dimensions but with a knobby or irregular contour. More than 90% of the reported PPNAD cases are associated with Carney complex; a multiple neoplasia syndrome; or the complex of spotty skin pigmentation, myxomas, and endocrine overactivity [2, 4]. Findings of PPNAD should initiate a search for Carney complex diagnosis on the basis of established criteria because multiple neoplasias and especially cardiac tumors, a component of the syndrome, may be asymptomatic and are potentially fatal [2–4]. Nikos Courcoutsakis Eunice Kennedy Shriver, National Institute of Child Health and Human Development National Institutes of Health Bethesda, MD Democritus University of Thrace Alexandroupolis, Greece Panos Prassopoulos Democritus University of Thrace Alexandroupolis, Greece Constantine A. Stratakis Eunice Kennedy Shriver, National Institute of Child Health and Human Development National Institutes of Health Bethesda, MD