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There is no computed tomography (CT)-based numerical index for predicting Cushing's syndrome (CS) in patients with adrenal incidentalomas. We tested the hypothesis that the iliopsoas muscle (Ip-M) to visceral fat (V-fat) ratio (IVR) on CT may predict CS in elderly female patients with adrenal tumors. We examined the V-fat area, subcutaneous fat (S-fat) area, Ip-M area, V-fat/S-fat ratio, and IVR at the third lumbar vertebra (L3) level using abdominal CT in female patients aged ≥50 years with cortisol-producing adrenal tumor diagnosed with CS or non-functioning adrenal tumor (NFT) in the derivation cohort. We performed receiver operating characteristic (ROC) analysis to evaluate the diagnostic value of the V-fat/S-fat ratio and IVR for predicting CS. We assessed the usefulness of the IVR in a separate validation cohort. In the derivation cohort, the IVR was significantly lower in the 9 patients with CS than in the 15 patients with NFT (p < 0.001). In ROC analysis with a cut-off value of 0.067, the IVR showed a sensitivity of 100%, specificity of 80.0%, positive likelihood ratio (PLR) of 5.000, and negative likelihood ratio (NLR) of 0.000. The area under the curve was significantly higher for the IVR than for the V-fat/S-fat ratio (0.933 vs. 0.704, respectively, p = 0.036). In 23 patients in the validation cohort, the IVR demonstrated a PLR of 5.714 and an NLR of 0.327. The novel IVR index, based on single-slice CT at the L3 level, predicted CS in elderly female patients with adrenal tumors.

Glucocorticoids play a critical role in the regulation of homeostasis, including metabolism. In patients with Cushing's syndrome, chronic glucocorticoid excess disrupts physiological internal milieu, resulting in central obesity, muscle atrophy, fatty liver, and insulin resistance. However, the relationship among various metabolic effects of glucocorticoids remains unknown. In the present study, we studied a male mouse model of Cushing's syndrome and indicated that glucocorticoid excess alters metabolic phenotype and body composition involving possible communication among skeletal muscle, liver, and adipose tissue.

We report herein the case of a 1-year-old boy with McCune-Albright syndrome (MAS) who presented with infantile-onset Cushing' s syndrome caused by ACTH independent macronodular adrenal hyperplasia (AIMAH). Abdominal CT, MRI, and adrenal scintigraphy with (131)I-adosterol identified bilateral adrenal involvement with the left adrenal gland being larger and functionally more active. Unilateral adrenalectomy of the left gland was performed and ameliorated many clinical symptoms, such as Cushingoid appearance and height restriction, and it also normalized many endocrinological data, such as diurnal rhythms of ACTH and cortisol, ACTH and cortisol responses to CRH, and urinary 24 hr free cortisol. Glucocorticoid was replaced for the first 1 year and 6 months after the operation. One adrenal crisis episode occurred at 3 weeks after the operation, but none have occurred since. These results suggest that unilateral adrenalectomy of the larger gland can be an alternative therapy for infantile onset Cushing' s syndrome caused by AIMAH with MAS, when asymmetric involvement is evident and the smaller gland is not markedly enlarged.

A right adrenal tumor was incidentally discovered on abdominal computed tomography performed on a 53-year-old Japanese man, who had been hospitalized with diabetic ketoacidosis. Normal values were obtained for adrenal hormones in the morning after an overnight fast and urinary cortisol excretion after treatment of diabetic ketoacidosis with insulin. However, overnight dexamethasone administration with 1 mg or 8 mg did not completely suppress serum cortisol levels. There were no remarkable physical findings related to Cushing's syndrome. The patient was diagnosed as having preclinical Cushing's syndrome (PCS). Histological examination of the adrenalectomy specimen demonstrated adrenal black adenoma. Blood glucose levels subsequently improved after adrenalectomy, and the patient never developed adrenal insufficiency after hydrocortisone withdrawal. The patient was treated with diet therapy alone, and maintained good glycemic control. However, the patient still showed a diabetic pattern in an oral glucose tolerance test. It seems that the existence of PCS in addition to the underlying type 2 diabetes mellitus contributed to aggravation of blood glucose levels. Although there are many aspects of the natural course of PCS that have not been thoroughly elucidated, it is necessary to remain aware that a PCS patient with abnormal glucose metabolism may develop diabetic ketoacidosis by environmental agents.

We describe a case of adrenocortical adenoma with preclinical Cushing's syndrome demonstrating diurnal rhythms of ACTH and cortisol in blood. A 50-year-old man was admitted to the hospital for the evaluation of incidental right adrenal mass with hyperglycemia and hypertension. On admission, there were no signs of clinical manifestation of hypercortisolism. The basal levels of cortisol (9.3 microg/dl) and ACTH (9.4 pg/ml) at 0800 h were not elevated and these diurnal rhythms were maintained. One or 8 mg of dexamethasone given orally overnight suppressed the plasma ACTH but not serum cortisol. Ultrasonogram, CT and scintiscan of (131)I adosterol all demonstrated an enlarged adrenal mass in the right adrenal gland. The right adrenal gland was subsequently resected by laparoscopic surgery. Histopathological findings of resected adrenal tumor were consistent with adrenocortical adenoma. Adjacent non-neoplastic adrenal tissue demonstrated adrenocortical atrophy but DHEA-sulfotransferase immunoreactivity in the zona reticularis was detected.

We report a rare case of ACTH-independent macronodular adrenal hyperplasia (AIMAH) with primary hyperparathyroidism (PHPT). A 57-year-old woman was admitted to our hospital for further examination of secondary hypertension and bilateral adrenal macrotumors. Midnight serum cortisol elevation with undetectable plasma ACTH, increased 24-hour urinary free cortisol excretion, and loss of the normal circadian rhythm in cortisol secretion established the diagnosis of Cushing's syndrome. Total resection of the enlarged left adrenal gland was performed with subsequent steroid replacement. Her general condition improved but serum calcium level increased 3 weeks after surgery. PHPT was diagnosed on the basis of endocrinological examination, although imaging studies failed to detect parathyroid lesion. In summary, we believe this to be the first report of a case of AIMAH with PHPT.

A 49-year-old man was referred to our hospital for the treatment of gallstones in 1993. Bilateral adrenal nodular masses were detected incidentally by abdominal computed tomography. He had no clinical signs of Cushing's syndrome such as central obesity, striae of skin and diabetes mellitus. We performed cholecystectomy and partial adrenalectomy of right adrenal gland as a biopsy, and diagnosed him as preclinical Cushing's syndrome due to adrenocorticotropin-independent bilateral adrenal macronodular hyperplasia (AIMAH) based on endocrinological and histological examinations. We followed him up for 7 years. During the observation period, the sizes of both adrenal glands increased gradually, and finally serum cortisol level increased beyond normal range, and he showed a Cushingoid appearance such as moon face and central obesity. His skin became atrophic and very fragile, and the bone mineral density of his lumbar spine was extremely low. Serum cortisol level was elevated, and plasma ACTH level was always suppressed. Urinary excretion of 17-hydroxycorticosteroid and free cortisol were increased. Diurnal rhythm of cortisol and ACTH was completely lost and high dose (8 mg/day) dexamethasone did not suppress urinary 17-hydroxycorticosteroid excretion. He became clinically overt Cushing's syndrome. We recommended total adrenalectomy, but he refused it. It is important to know the natural history of preclinical Cushing's syndrome due to AIMAH when choosing an adequate treatment.

A 74-year-old man developed Cushing's syndrome and hypokalemia due to ACTH-independent bilateral macronodular adrenocortical hyperplasia (AIMAH) with excessive secretion of mineralocorticoid hormones. Plasma concentrations of weak mineralocorticoids were high. The increase in plasma cortisol did not have a diurnal rhythm, and was not suppressed by a high dose of dexamethasone. Plasma ACTH was undetectable, but plasma cortisol was increased by ACTH administration. The concentrations of mineralocorticoids, especially deoxycorticosterone and corticosterone were increased, and augmented the response to ACTH administration. Plasma renin activity and aldosterone concentrations were rather suppressed. Both adrenal glands, with a total weight of 110 g, were enlarged and contained several macronodules. These nodules were composed of hyperplasia of small cortical cells and usual clear cells. This is a rare case of ACTH-independent bilateral macronodular adrenocortical hyperplasia because there were excessive secretion of mineralocorticoid and hypokalemia.

We examined the role of PKC in cortisol secretion from adrenocortical adenomas. Isolated cells were prepared from aldosterone producing adenoma (APA, n=5), APA complicated with pre-clinical Cushing's syndrome (APA+PC, n=1), PC (n=2), and cortisol producing adenoma (CPA, n=5). They were stimulated with 100 nM ACTH, 1 microM forskolin (FS), 1 microM tetradecanoyl phorbol 13-acetate (TPA), and 100 nM angiotensin II (AngII). ACTH was most potent to secret cortisol. FS also stimulated cortisol secretion, but did less-potently. TPA and AngII also stimulated cortisol secretion significantly in cells from CPA. Furthermore, ACTH- and TPA-induced PKCalpha and beta translocations from cytosol to membrane were observed in adenoma cells from APA+PC, PC, and CPA. In conclusion, it was suggested that ACTH-induced cortisol secretion may be mediated by both PKC and protein kinase A in adrenocortical adenomas, and that PKC-mediated signal transduction may be involved in ACTH-induced cortisol secretion in CPA.

The steroidogenic activities in non-hyperfunctioning adrenal adenoma (NHFA) have not yet been fully examined. Steroid content both in adenoma and its non-tumorous adjacent adrenal tissue was measured by the HPLC system in 8 cases of NHFA and 2 cases of preclinical Cushing's syndrome (PCS). Activities of cytochrome P450c17alpha, P450c21, P450c11beta, P450c18 and aldosterone-synthesizing enzyme (P450aldo) were also determined by the enzyme reconstitution system. Steroid content in NHFA varied but no significant difference was seen between NHFA and normal control adrenals. Activities of all P450s except P450aldo were confirmed in NHFA, but they were almost equivalent to those in normal control adrenals. As no significant difference between NHFA and normal controls was observed in either steroid contents or P450s activities, the steroidogenic activity of NHFA is considered to be comparable to that of normal adrenals.

We report clinical findings and steroidogenic activities in adrenal tissues in 2 cases of AIMAH. Endocrine studies revealed an undetectable level of plasma ACTH and a diminished circadian rhythm of plasma cortisol. A significant increase in plasma cortisol levels in response to ACTH stimulation was observed in both cases. After the administration of metyrapone in one case, urinary excretion of 17-hydroxycorticosteroid (17-OHCS) significantly increased, although the plasma ACTH level did not respond. Computed tomography showed large masses in both adrenal glands, and bilateral uptake was identified on adrenal scintigraphy. The totals for the bilateral adrenal glands were 98 g and 105 g, respectively, and the left adrenal was larger than the right in both cases. Steroid content in the nodules measured by high performance liquid chromatography (HPLC) showed that the cortisol content was definitely lower than that in cortisol-producing adenoma (CPA) and even in normal adrenals. The activities of cytochrome P450c17, P450c21 and P450c11 were evaluated in one case, and all of them were reduced in the nodules. Especially that of P450c17 was remarkably reduced. These data suggest that cortisol production in AIMAH is inefficient, and that the cause of Cushing's syndrome may be related to the marked increase in the number of cells or bulk of the tumor.

A 55-year-old woman developed Cushing's syndrome due to ACTH-independent bilateral adrenocortical macronodular hyperplasia. Plasma ACTH was undetectable, and was not stimulated by administration of metyrapone, CRH, or insulin. Hypercortisolism was not suppressed by a high dose of dexamethasone, but was responsive to ACTH. Both adrenal glands were enlarged with a total weight of 200 g, and contained multiple nodules composed of two cell types (large clear cells and small compact cells). In immunohistochemical studies, P450c17 immunoreactivity was predominantly observed in small compact cortical cells, while that of 3 beta HSD was observed exclusively in large clear cortical cells. This pattern of expression of steroidogenic enzymes as well as histological and clinical features is considered to be unique to ACTH-independent bilateral adrenocortical macronodular hyperplasia.