Histopathology of the human adrenal cortex

In Situ Spatial Reconstruction of Distinct Normal and Pathological Cell Populations Within the Human Adrenal Gland

The human adrenal gland consists of concentrically organized, functionally distinct regions responsible for hormone production. Dysregulation of adrenocortical cell differentiation alters the proportion and organization of the functional zones of the adrenal cortex leading to disease. Current models of adrenocortical cell differentiation are based on mouse studies, but there are known organizational and functional differences between human and mouse adrenal glands. This study aimed to investigate the centripetal differentiation model in the human adrenal cortex and characterize aldosterone-producing micronodules (APMs) to better understand adrenal diseases such as primary aldosteronism. We applied spatially resolved in situ transcriptomics to human adrenal tissue sections from 2 individuals and identified distinct cell populations and their positional relationships. The results supported the centripetal differentiation model in humans, with cells progressing from the outer capsule to the zona glomerulosa, zona fasciculata, and zona reticularis. Additionally, we characterized 2 APMs in a 72-year-old woman. Comparison with earlier APM transcriptomes indicated a subset of core genes, but also heterogeneity between APMs. The findings contribute to our understanding of normal and pathological cellular differentiation in the human adrenal cortex.

Regulation of lipid droplets and cholesterol metabolism in adrenal cortical cells

The adrenal gland is composed of two distinctly different endocrine moieties. The interior medulla consists of neuroendocrine chromaffin cells that secrete catecholamines like adrenaline and noradrenaline, while the exterior cortex consists of steroidogenic cortical cells that produce steroid hormones, such as mineralocorticoids (aldosterone), glucocorticoids (cortisone and cortisol) and androgens. Synthesis of steroid hormones in cortical cells requires substantial amounts of cholesterol, which is the common precursor for steroidogenesis. Cortical cells may acquire cholesterol from de novo synthesis and uptake from circulating low- and high-density lipoprotein particles (LDL and HDL). As cholesterol is part of the plasma membrane in all mammalian cells and an important regulator of membrane fluidity, cellular levels of free cholesterol are tightly regulated. To ensure a robust supply of cholesterol for steroidogenesis and to avoid cholesterol toxicity, cortical cells store large amounts of cholesterol as cholesteryl esters in intracellular lipid droplets. Cortical steroidogenesis relies on both mobilization of cholesterol from lipid droplets and constant uptake of circulating cholesterol to replenish lipid droplet stores. This chapter will describe mechanisms involved in cholesterol uptake, cholesteryl ester synthesis, lipid droplet formation, hydrolysis of stored cholesteryl esters, as well as their impact on steroidogenesis. Additionally, animal models and human diseases characterized by altered cortical cholesteryl ester storage, with or without abnormal steroidogenesis, will be discussed.

Exploration of KCNJ5 Somatic Mutation and CYP11B1/CYP11B2 Staining in Multiple Nodules in Primary Aldosteronism

Objective

Unilateral primary aldosteronism (PA) includes aldosterone-producing adenoma (APA), unilateral adrenal hyperplasia, and unilateral multiple nodules. The correlation of multiple nodules, especially genotypic and pathological characteristics, remains unknown. KCNJ5 mutation accounts for 60-80% of unilateral PA, so we aimed to explore the correlation of KCNJ5 somatic mutation and CYP11B1/CYP11B2 staining in multiple nodules in unilateral PA.

Design and Methods

A total of 56 microdissected nodules from 24 patients with unilateral PA were included. We assessed somatic KCNJ5 mutations, immunohistochemistry for aldosterone synthase (CYP11B2)/cortisol synthase (CYP11B1), and histological cellular composition of nodules together with adjacent adrenal cortical statements.

Results

KCNJ5 mutations were identified in 17 (17/56, 30.4%) nodules from 11 adrenals (11/24, 45.8%). All KCNJ5-mutant nodules were positive for CYP11B2 staining, 6 cases (6/11) had only one KCNJ5-mutant nodular, and the other 5 cases (5/11) had more than one KCNJ5-mutant nodules. Three cases (3/11) had different KCNJ5 mutations in individual nodules. Compared with KCNJ5-positive adrenals, the cortices adjacent to the nodules in KCNJ5-negative adrenals showed significant proliferation (p = 0.004). CYP11B2/CYP11B1 expression patterns revealed great heterogeneity in intensity and range both in KCNJ5-mutant nodules and KCNJ5-WT ones.

Conclusion

There is great heterogeneity among nodules from patients with unilateral PA. Countable nodules could be considered as multiple APAs, featuring somatic KCNJ5 mutation, positive CYP11B2 staining, and lack of adjacent cortical proliferation in unilateral multiple nodules.

Cellular Senescence in Adrenocortical Biology and Its Disorders

Cellular senescence is considered a physiological process along with aging and has recently been reported to be involved in the pathogenesis of many age-related disorders. Cellular senescence was first found in human fibroblasts and gradually explored in many other organs, including endocrine organs. The adrenal cortex is essential for the maintenance of blood volume, carbohydrate metabolism, reaction to stress and the development of sexual characteristics. Recently, the adrenal cortex was reported to harbor some obvious age-dependent features. For instance, the circulating levels of aldosterone and adrenal androgen gradually descend, whereas those of cortisol increase with aging. The detailed mechanisms have remained unknown, but cellular senescence was considered to play an essential role in age-related changes of the adrenal cortex. Recent studies have demonstrated that the senescent phenotype of zona glomerulosa (ZG) acts in association with reduced aldosterone production in both physiological and pathological aldosterone-producing cells, whereas senescent cortical-producing cells seemed not to have a suppressed cortisol-producing ability. In addition, accumulated lipofuscin formation, telomere shortening and cellular atrophy in zona reticularis cells during aging may account for the age-dependent decline in adrenal androgen levels. In adrenocortical disorders, including both aldosterone-producing adenoma (APA) and cortisol-producing adenoma (CPA), different cellular subtypes of tumor cells presented divergent senescent phenotypes, whereby compact cells in both APA and CPA harbored more senescent phenotypes than clear cells. Autonomous cortisol production from CPA reinforced a local cellular senescence that was more severe than that in APA. Adrenocortical carcinoma (ACC) was also reported to harbor oncogene-induced senescence, which compensatorily follows carcinogenesis and tumor progress. Adrenocortical steroids can induce not only a local senescence but also a periphery senescence in many other tissues. Therefore, herein, we systemically review the recent advances related to cellular senescence in adrenocortical biology and its associated disorders.

Preclinical Pharmacokinetics and Metabolism of MAK683, a Clinical Stage Selective Oral Embryonic Ectoderm Development (EED) Inhibitor for Cancer Treatment

1. MAK683 (N-((5-fluoro-2,3-dihydrobenzofuran-4-yl)methyl)-8-(2-methylpyridin-3-yl)-[1,2,4]triazolo[4,3-c]pyrimidin-5-amine) is a potent and orally bioavailable EED inhibitor for the potential treatment in oncology. Pharmacokinetics (PK) in preclinical species are characterized by low to moderate plasma clearances, high oral exposure and moderate to high oral bioavailability at dose of 1-2 mg/kg.2. A species comparison of the metabolic pathways of MAK683 has been made using [¹⁴C]MAK683 incubations with liver microsomes and hepatocytes from rat, dog, cynomolgus monkey and human. Overall, the in vitro hepatic metabolism pathway of MAK683 in all five species was very complex. A total of 60 metabolites with 19 metabolites greater than 1.5% of the total integrated area in the radiochromatogram of at least one species were identified in five species (rat, mouse, dog, monkey and human).3. The primary in vitro hepatic oxidative metabolism pathway identified in human involved 2-hydroxylation of the dihydrofuran ring to form an alcohol (M28), which was in a chemical equilibrium favoring the formation of its aldehyde form. The aldehyde was then oxidized to the carboxylic acid metabolite (M26) or reduced to the O-hydroxyethylphenol (M29). N-dealkylation (M1), 3-hydroxylation of the dihydrofuran ring (M27), N-oxidation of the pyridine moiety (M53) and sulfate conjugation of M28 to form M19 were also important biotransformation pathways in human hepatocytes. The above major human hepatic metabolic pathways were also observed across the animal species (rat, mouse, dog and monkey) mostly providing precursors for the formation of other metabolites via further oxygenation, glucuronidation, and sulfation pathways.4. No human specific metabolites were observed. In addition, in-vivo biotransformation was also conducted in bile-duct cannulated (BDC) rat. The metabolism in BDC rat was similar to these observed the in vitro hepatocytes.

Adrenal medulla development and medullary-cortical interactions

The mammalian adrenal gland is composed of two distinct tissue types in a bidirectional connection, the catecholamine-producing medulla derived from the neural crest and the mesoderm-derived cortex producing steroids. The medulla mainly consists of chromaffin cells derived from multipotent nerve-associated descendants of Schwann cell precursors. Already during adrenal organogenesis, close interactions between cortex and medulla are necessary for proper differentiation and morphogenesis of the gland. Moreover, communication between the cortex and the medulla ensures a regular function of the adult adrenal. In tumor development, interfaces between the two parts are also common. Here, we summarize the development of the mammalian adrenal medulla and the current understanding of the cortical-medullary interactions under development and in health and disease.

International Histopathology Consensus for Unilateral Primary Aldosteronism

OBJECTIVE

Develop a consensus for the nomenclature and definition of adrenal histopathologic features in unilateral primary aldosteronism (PA).

CONTEXT

Unilateral PA is the most common surgically treated form of hypertension. Morphologic examination combined with CYP11B2 (aldosterone synthase) immunostaining reveals diverse histopathologic features of lesions in the resected adrenals.

PATIENTS AND METHODS

Surgically removed adrenals (n = 37) from 90 patients operated from 2015 to 2018 in Munich, Germany, were selected to represent the broad histologic spectrum of unilateral PA. Five pathologists (Group 1 from Germany, Italy, and Japan) evaluated the histopathology of hematoxylin-eosin (HE) and CYP11B2 immunostained sections, and a consensus was established to define the identifiable features. The consensus was subsequently used by 6 additional pathologists (Group 2 from Australia, Brazil, Canada, Japan, United Kingdom, United States) for the assessment of all adrenals with disagreement for histopathologic diagnoses among group 1 pathologists.

RESULTS

Consensus was achieved to define histopathologic features associated with PA. Use of CYP11B2 immunostaining resulted in a change of the original HE morphology-driven diagnosis in 5 (14%) of 37 cases. Using the consensus criteria, group 2 pathologists agreed for the evaluation of 11 of the 12 cases of disagreement among group 1 pathologists.

CONCLUSION

The HISTALDO (histopathology of primary aldosteronism) consensus is useful to standardize nomenclature and achieve consistency among pathologists for the histopathologic diagnosis of unilateral PA. CYP11B2 immunohistochemistry should be incorporated into the routine clinical diagnostic workup to localize the likely source of aldosterone production.

Topical Diagnosis and Determination of the Primary Hyperaldosteronism Variant

Laboratory diagnosis of primary hyperaldosteronism is based on determining blood levels of aldosterone, renin on request, potassium, and sodium. The results of these studies are significantly influenced by drugs, preparation for the study and blood collection methods, age, gender, and concomitant diseases. The work analyzes the factors influencing the results of the study of aldosterone and identifies the main ways of their exclusion at each stage of the diagnosis. Their neglecting is the determining factor in obtaining false results, diagnostic errors, the selection of ill-treatment tactics, and inadequate treatment. All these diagnostic problems are covered in a variety of ways in the review, which is based on the analysis of results of individual authors' research and practical and clinical recommendations from leading world endocrinological associations. Results of laboratory diagnostics of PHA depend on the influence of many factors. Among them, it is essential to use different medication drugs, the rules for preparing for the study, and the method of conducting it. In assessing the results of research, it is necessary to take into account not only the indicators of the level of aldosterone in the blood but also the features of the clinical course of the disease, its compliance to the drug therapy, age, and gender of the patients.

Laboratory Diagnostics of Primary Hyperaldosteronism and its Peculiarities (Literature Review)

The final stage of the diagnostic of primary hyperaldosteronism is to identify the causes of excessive secretion of aldosterone and determination of its variants. Based on the analysis of literature data, the diagnostic value, sensitivity and specificity of the methods of radiation diagnostics for primary hyperaldosteronism were assessed: ultrasound, computed tomography, magnetic resonance imaging, photon emission tomography, magnetic resonance spectroscopy, scintigraphy with iodine radiopharmaceuticals. The causes of false-positive and false-negative evaluations of changes in adrenal glands in the application of these diagnostics have been analyzed. There are many genetic and morphological studies when searching the literature data on the principles and methods of distinguishing the nosological forms of primary hyperaldosteronism based on the results of the aldosterone level estimation in the separated blood from the central veins of both adrenal glands or segmental veins of one gland with subsequent determination of the concentration gradient. It was noted that topical diagnostics and, especially, the determination of nosological forms of primary hyperaldosteronism are complex and expensive, but their results allow choosing an appropriate treatment approach for each particular case.

Somatic PRKACA Mutations: Association With Transition From Pituitary-Dependent to Adrenal-Dependent Cushing Syndrome

CONTEXT

Prolonged adrenal stimulation by corticotropin, as in long-standing Cushing disease (CD), leads to diffuse to nodular hyperplasia. Adrenal functional autonomy has been described in a subset of patients with CD, leading to the hypothesis of transition from ACTH-dependent to ACTH-independent hypercortisolism.

OBJECTIVE

With the consideration that the catalytic α subunit of protein kinase A (PKA; PRKACA) somatic mutations are the most common finding in adrenal adenomas associated with ACTH-independent Cushing syndrome, our aim was to analyze PRKACA mutations in adrenals of patients with persistent/long-standing CD.

DESIGN

Cross-sectional.

SETTING

University hospital.

PATIENTS

Two patients with long-standing CD and suspicion of coexistence of autonomous adrenal hyperfunction, according to pre and postoperative evaluations, were selected for this study, following an intensive literature search and patient-chart reviewing.

INTERVENTION

Clinical data were analyzed. DNA was extracted from adrenal tissue for PRKACA sequencing. PKA activity was assayed.

MAIN OUTCOME MEASURE

PRKACA somatic mutations.

RESULTS

Both patients showed mutations of PRKACA in the macronodule in the context of micronodular adrenal hyperplasia. One patient harbored the previously described p.Leu206Arg substitution, whereas a p.Ser213Arg missense variation was detected in the adrenal nodule of the second patient. No mutations were detected in the adjacent adrenal cortex of the second patient. In silico analysis predicts that p.Ser213Arg can interfere with the interaction between the regulatory and catalytic subunits of PKA.

CONCLUSIONS

Our study shows that PRKACA somatic mutations can be found in adrenal nodules of patients with CD. These genetic alterations could represent a possible mechanism underlying adrenal nodule formation and autonomous cortisol hyperproduction in a subgroup of patients with long-standing CD.

In situ metabolomics of aldosterone-producing adenomas

Recent genetic examinations and multisteroid profiles have provided the basis for subclassification of aldosterone-producing adenomas (APAs). The objective of the current study was to produce a comprehensive, high-resolution mass spectrometry imaging (MSI) map of APAs in relation to morphometry, immunohistochemical profiles, mutational status, and clinical outcome. The study cohort comprised 136 patients with unilateral primary aldosteronism. Matrix-assisted laser desorption/ionization-Fourier transform-ion cyclotron resonance MSI was conducted, and metabolite profiles were analyzed with genotype/phenotype information, including digital image analysis from morphometry and IHC of steroidogenic enzymes. Distinct molecular signatures between KCNJ5- and CACNA1D-mutated APAs with significant differences of 137 metabolites, including metabolites of purine metabolism and steroidogenesis, were observed. Intratumor concentration of 18-oxocortisol and 18-hydroxycortisol were inversely correlated with the staining intensity of CYP11B1. Lower staining intensity of CYP11B1 and higher levels of 18-oxocortisol were associated with a higher probability of complete clinical success after surgery. The present study demonstrates distinct metabolomic profiles of APAs in relation to tumor genotype. In addition, we reveal an inverse correlation between cortisol derivatives and CYP11B1 and the impact of 18-oxocortisol and CYP11B1 on clinical outcome, which provides unprecedented insights into the pathophysiology, clinical features, and steroidogenesis of APAs.

Role of Cryptochrome-1 and Cryptochrome-2 in Aldosterone-Producing Adenomas and Adrenocortical Cells

Mice lacking the core-clock components, cryptochrome-1 (CRY1) and cryptochrome-2 (CRY2) display a phenotype of hyperaldosteronism, due to the upregulation of type VI 3β-hydroxyl-steroid dehydrogenase (Hsd3b6), the murine counterpart to the human type I 3β-hydroxyl-steroid dehydrogenase (HSD3B1) gene. In the present study, we evaluated the role of CRY1 and CRY2 genes, and their potential interplay with HSD3B isoforms in adrenal pathophysiology in man. Forty-six sporadic aldosterone-producing adenomas (APAs) and 20 paired adrenal samples were included, with the human adrenocortical cells HAC15 used as the in vitro model. In our cohort of sporadic APAs, CRY1 expression was 1.7-fold [0.75–2.26] higher (p = 0.016), while CRY2 showed a 20% lower expression [0.80, 0.52–1.08] (p = 0.04) in APAs when compared with the corresponding adjacent adrenal cortex. Type II 3β-hydroxyl-steroid dehydrogenase (HSD3B2) was 317-fold [200–573] more expressed than HSD3B1, and is the main HSD3B isoform in APAs. Both dehydrogenases were more expressed in APAs when compared with the adjacent cortex (5.7-fold and 3.5-fold, respectively, p < 0.001 and p = 0.001) and HSD3B1 was significantly more expressed in APAs composed mainly of zona glomerulosa-like cells. Treatment with angiotensin II (AngII) resulted in a significant upregulation of CRY1 (1.7 ± 0.25-fold, p < 0.001) at 6 h, and downregulation of CRY2 at 12 h (0.6 ± 0.1-fold, p < 0.001), through activation of the AngII type 1 receptor. Independent silencing of CRY1 and CRY2 genes in HAC15 cells resulted in a mild upregulation of HSD3B2 without affecting HSD3B1 expression. In conclusion, our results support the hypothesis that CRY1 and CRY2, being AngII-regulated genes, and showing a differential expression in APAs when compared with the adjacent adrenal cortex, might be involved in adrenal cell function, and in the regulation of aldosterone production.

Impact of aldosterone-producing cell clusters on diagnostic discrepancies in primary aldosteronism

Adrenocorticotropic hormone (ACTH) stimulation is recommended in adrenal vein sampling (AVS) for primary aldosteronism (PA) to improve the AVS success rate. However, this method can confound the subtype diagnosis. Gene mutations or pathological characteristics may be related to lateralization by AVS. This study aimed to compare the rate of diagnostic discrepancy by AVS pre- versus post-ACTH stimulation and to investigate the relationship between this discrepancy and findings from immunohistochemical and genetic analyses of PA. We evaluated 195 cases of AVS performed in 2011–2017. All surgical specimens were analyzed genetically and immunohistochemically. Based on the criteria, AVS was successful in 158 patients both pre- and post-ACTH; of these patients, 75 showed diagnostic discrepancies between pre- and post-ACTH. Thus, 19 patients underwent unilateral adrenalectomy, of whom 16 had an aldosterone-producing adenoma (APA) that was positive for CYP11B2 immunostaining. Of them, 10 patients had discordant lateralization between pre- and post-ACTH. In the genetic analysis, the rate of somatic mutations was not significantly different between APA patients with versus without a diagnostic discrepancy. In the immunohistochemical analysis, CYP11B2 levels and the frequency of aldosterone-producing cell clusters (APCCs) in APAs were almost identical between patients with versus without a diagnostic discrepancy. However, both the number and summed area of APCCs in APAs were significantly smaller in patients with concordant results than in those whose diagnosis changed to bilateral PA post-ACTH stimulation. In conclusion, lateralization by AVS was affected by APCCs in the adjacent gland, but not by APA-related factors such as somatic gene mutations.

Genetic Causes of Functional Adrenocortical Adenomas

Aldosterone and cortisol, the main mineralocorticoid and glucocorticoid hormones in humans, are produced in the adrenal cortex, which is composed of three concentric zones with specific functional characteristics. Adrenocortical adenomas (ACAs) can lead to the autonomous secretion of aldosterone responsible for primary aldosteronism, the most frequent form of secondary arterial hypertension. In the case of cortisol production, ACAs lead to overt or subclinical Cushing syndrome. Genetic analysis driven by next-generation sequencing technology has enabled the discovery, during the past 7 years, of the genetic causes of a large subset of ACAs. In particular, somatic mutations in genes regulating intracellular ionic homeostasis and membrane potential have been identified in aldosterone-producing adenomas. These mutations all promote increased intracellular calcium concentrations, with activation of calcium signaling, the main trigger for aldosterone production. In cortisol-producing adenomas, recurrent somatic mutations in PRKACA (coding for the cyclic adenosine monophosphate-dependent protein kinase catalytic subunit α) affect cyclic adenosine monophosphate-dependent protein kinase A signaling, leading to activation of cortisol biosynthesis. In addition to these specific pathways, the Wnt/β-catenin pathway appears to play an important role in adrenal tumorigenesis, because β-catenin mutations have been identified in both aldosterone- and cortisol-producing adenomas. This, together with different intermediate states of aldosterone and cortisol cosecretion, raises the possibility that the two conditions share a certain degree of genetic susceptibility. Alternatively, different hits might be responsible for the diseases, with one hit leading to adrenocortical cell proliferation and nodule formation and the second specifying the hormonal secretory pattern.

Histopathological and genetic characterization of aldosterone-producing adenomas with concurrent subclinical cortisol hypersecretion: a case series

PURPOSE

Aldosterone-producing adenomas with concurrent subclinical cortisol hypersecretion are reported in an increasing number of patients. Five aldosterone-producing adenomas from patients with primary aldosteronism and subclinical hypercortisolism were examined.

THE AIMS OF OUR STUDY WERE

(1) to analyze pathological features and immunohistochemical expression of CYP11B1 (11β-hydroxylase) and CYP11B2 (aldosterone synthase) in these tumors; (2) to investigate somatic mutations involved in adrenal steroid hypersecretion and/or tumor growth.

METHODS

Archival micro-dissected paraffin-embedded slides from tumor specimens were used for histological and molecular studies. Immunohistochemistry was performed using monoclonal anti-CYP11B1 and anti-CYP11B2 antibodies. Cellular composition was determined by examining for known features of zona fasciculata and zona glomerulosa, and immunoreactivity for CYP11B1 and CYP11B2 by McCarty H-score. Spot regions for mutations in KCNJ5, ATP1A1, ATP2B3, CACNA1D, PRKACA, and CTNNB1 gene sequences were evaluated.

RESULTS

Four APAs showed a predominant (≥50%) zona fasciculata-like cell pattern: one tumor had CYP11B1 H-score = 150, no detectable CYP11B2 expression, and harbored a PRKACA p.Leu206Arg mutation (that we have reported previously elsewhere), one had no CYP11B1 expression, CYP11B2 H-score = 40, and no mutations; the remaining two adenomas had high CYP11B1 H-score (160 and 240, respectively) and low CYP11B2 H-score (30 and 15, respectively), with the latter harboring a CTNNB1 p.Ser45Phe activating mutation. One of five aldosterone-producing adenomas had a predominant zona glomerulosa-like pattern, CYP11B1 H-score = 15, CYP11B2 H-score = 180, and no mutations.

CONCLUSIONS

The majority of aldosterone-producing adenomas with concurrent subclinical cortisol hypersecretion were composed mainly of zona fasciculata-like cells, while CYP11B1 and CYP11B2 immunostaining demonstrated clear heterogeneity. In a subset of cases, different somatic mutations may be involved in hormone excess and tumor formation.

Somatic and inherited mutations in primary aldosteronism

Primary aldosteronism (PA), the most common form of secondary hypertension, is caused in the majority of cases by unilateral aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia. Over the past few years, somatic mutations in KCNJ5, CACNA1D, ATP1A1 and ATP2B3 have been proven to be associated with APA development, representing more than 50% of sporadic APA. The identification of these mutations has allowed the development of a model for APA involving modification on the intracellular ionic equilibrium and regulation of cell membrane potential, leading to autonomous aldosterone overproduction. Furthermore, somatic CTNNB1 mutations have also been identified in APA, but the link between these mutations and APA development remains unknown. The sequence of events responsible for APA formation is not completely understood, in particular, whether a single hit or a double hit is responsible for both aldosterone overproduction and cell proliferation. Germline mutations identified in patients with early-onset PA have expanded the classification of familial forms (FH) of PA. The description of germline KCNJ5 and CACNA1H mutations has identified FH-III and FH-IV based on genetic findings; germline CACNA1D mutations have been identified in patients with very early-onset PA and severe neurological abnormalities. This review summarizes current knowledge on the genetic basis of PA, the association of driver gene mutations and clinical findings and in the contribution to patient care, plus the current understanding on the mechanisms of APA development.

Primary Aldosteronism: Changing Definitions and New Concepts of Physiology and Pathophysiology Both Inside and Outside the Kidney

In the 60 years that have passed since the discovery of the mineralocorticoid hormone aldosterone, much has been learned about its synthesis (both adrenal and extra-adrenal), regulation (by renin-angiotensin II, potassium, adrenocorticotrophin, and other factors), and effects (on both epithelial and nonepithelial tissues). Once thought to be rare, primary aldosteronism (PA, in which aldosterone secretion by the adrenal is excessive and autonomous of its principal regulator, angiotensin II) is now known to be the most common specifically treatable and potentially curable form of hypertension, with most patients lacking the clinical feature of hypokalemia, the presence of which was previously considered to be necessary to warrant further efforts towards confirming a diagnosis of PA. This, and the appreciation that aldosterone excess leads to adverse cardiovascular, renal, central nervous, and psychological effects, that are at least partly independent of its effects on blood pressure, have had a profound influence on raising clinical and research interest in PA. Such research on patients with PA has, in turn, furthered knowledge regarding aldosterone synthesis, regulation, and effects. This review summarizes current progress in our understanding of the physiology of aldosterone, and towards defining the causes (including genetic bases), epidemiology, outcomes, and clinical approaches to diagnostic workup (including screening, diagnostic confirmation, and subtype differentiation) and treatment of PA.

Methodology for Using 3-Dimensional Sonography to Measure Fetal Adrenal Gland Volumes in Pregnant Women With and Without Early Life Stress

Fetal adrenal gland volumes on 3-dimensional sonography have been studied as potential predictors of preterm birth. However, no consistent methodology has been published. This article describes the methodology used in a study that is evaluating the effects of maternal early life stress on fetal adrenal growth to allow other researchers to compare methodologies across studies. Fetal volumetric data were obtained in 36 women at 20 to 22 and 28 to 30 weeks' gestation. Two independent examiners measured multiple images of a single fetal adrenal gland from each sonogram. Intra- and inter-rater consistency was examined. In addition, fetal adrenal volumes between male and female fetuses were reported. The intra- and inter-rater reliability was satisfactory when the mean of 3 measurements from each rater was used. At 20 weeks' gestation, male fetuses had larger average adjusted adrenal volumes than female fetuses (mean, 0.897 versus 0.638; P = .004). At 28 weeks' gestation, the fetal weight was more influential in determining values for adjusted fetal adrenal volume (0.672 for male fetuses versus 0.526 for female fetuses; P = .034). This article presents a methodology for assessing fetal adrenal volume using 3-dimensional sonography that can be used by other researchers to provide more consistency across studies.

Immunohistochemistry of the adrenal in primary aldosteronism

PURPOSE OF REVIEW

Primary aldosteronism is a major cause of hypertension; aldosterone-producing adenomas (APA) cause about half of primary aldosteronism; idiopathic hyperplasia of adrenal glomerulosa cells are responsible for the rest. A surprising variety of mutations have recently been identified in ion channels and pumps in a significant number of APA. The present review addresses histological and molecular aspects of APA and the surrounding adrenal.

RECENT FINDINGS

Specific antibodies against the CYP11B2 and CYP11B1 enzymes, the last enzyme in aldosterone and cortisol synthesis, respectively, allow for the first time study of the steroidogenic capabilities of cells within the APA and adjacent adrenal. Cells expressing CYP11B2 may be scattered and/or in clusters throughout the normal adrenal zona glomerulosa. APA differ widely in the number of cells expressing CYP11B2; some did not express it at all, but were surrounded by cells, some in clusters or micronodules, that expressed CYP11B2. Some APAs also comprised cells expressing both CYP11B1 and CYP17A1. In some samples, analysis of the tissue adjacent to APA detected ion channel and pump mutations heretofore associated only with APA.

SUMMARY

APAs have a complex structure and expression of steroidogenic enzymes.

Immunohistochemical, genetic and clinical characterization of sporadic aldosterone-producing adenomas

Adrenal glands removed for unilateral primary aldosteronism (PA) display marked histological heterogeneity. Recently reported somatic mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D can partially account for these differences. In this study we aimed at combining phenotypic and genotypic characteristics, integrating genetic and immunohistochemistry correlates in sporadic PA. Seventy-one adrenal glands have been included in the study and analyzed for mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D. Histological examination and immunohistochemical staining for CYP11B1 (11β-hydroxylase) and CYP11B2 (aldosterone synthase) were performed on aldosterone-producing adenomas (APAs) and adjacent adrenal cortex. In our cohort, the final histopathological diagnosis was multinodular hyperplasia in 22.5% of the patients and single nodule in 77.5%. Forty-five percent of the removed adrenals displayed extra-APA CYP11B2-positive cell nests (B2-CN). Among adrenal vein sampling parameters the suppression of contralateral adrenal was more frequent and the lateralization index was higher in the subgroup of patients without extra-APA B2-CN compared to the subgroup with extra-APA B2-CN. KCNJ5-mutated APAs were composed mainly of zona fasciculata-like cells with high expression of CYP11B1, while ATP1A1, ATP2B3 and CACNA1D-mutated APAs presented more frequently a zona-glomerulosa-like phenotype with high expression of CYP11B2. We observed a significant inverse correlation between CYP11B2 expression and the size of the nodules and, if CYP11B2 expression was corrected for tumor volume, a significant correlation with plasma aldosterone and aldosterone to renin ratio. Our findings indicate that combination of genotyping and immunohistochemistry improves the final histopathological diagnosis between single nodule and multinodular hyperplasia of the assessed adrenals.

Adrenal CYP11B1/2 expression in primary aldosteronism: immunohistochemical analysis using novel monoclonal antibodies

CYP11B1 and CYP11B2 play pivotal roles in adrenocorticosteroids synthesis. We performed semi-quantitative immunohistochemical analysis of these proteins in adrenals from patients with primary aldosteronism using novel monoclonal antibodies. Clusters of cortical cells positive for CYP11B2 were detected in the zona glomerulosa (ZG) of normal adrenal gland (NA), idiopathic hyperaldosteronism (IHA) and the adjacent adrenal of aldosterone-producing adenoma (APA). In APA, heterogenous immunolocalization of CYP11B2 and diffuse immunoreactivity of CYP11B1 were detected in tumor cells, respectively. The relative immunoreactivity of CYP11B2 in the ZG of adjacent adrenal of APA was significantly lower than that of NA, IHA and APA tumor cells, suggestive of suppressed aldosterone biosynthesis in these cells. These findings did indicate the regulatory mechanisms of aldosterone biosynthesis were different between normal/hyperplastic and neoplastic aldosterone-producing cells in human adrenals. CYP11B2 immunoreactivity in the ZG could also serve as a potential immunohistochemical marker differentiating morphologically hyperplastic ZG of IHA and APA adjacent adrenal.

Genetic spectrum and clinical correlates of somatic mutations in aldosterone-producing adenoma

Primary aldosteronism is the most common form of secondary hypertension. Somatic mutations in KCNJ5, ATP1A1, ATP2B3, and CACNA1D have been described in aldosterone-producing adenomas (APAs). Our aim was to investigate the prevalence of somatic mutations in these genes in unselected patients with APA (n=474), collected through the European Network for the Study of Adrenal Tumors. Correlations with clinical and biochemical parameters were first analyzed in a subset of 199 patients from a single center and then replicated in 2 additional centers. Somatic heterozygous KCNJ5 mutations were present in 38% (180/474) of APAs, whereas ATP1A1 mutations were found in 5.3% (25/474) and ATP2B3 mutations in 1.7% (8/474) of APAs. Previously reported somatic CACNA1D mutations as well as 10 novel CACNA1D mutations were identified in 44 of 474 (9.3%) APAs. There was no difference in the cellular composition of APAs or in CYP11B2, CYP11B1, KCNJ5, CACNA1D, or ATP1A1 gene expression in APAs across genotypes. Patients with KCNJ5 mutations were more frequently female, diagnosed younger, and with higher minimal plasma potassium concentrations compared with CACNA1D mutation carriers or noncarriers. CACNA1D mutations were associated with smaller adenomas. These associations were largely dependent on the population structure of the different centers. In conclusion, recurrent somatic mutations were identified in 54% of APAs. Young women with APAs are more likely to be KCNJ5 mutation carriers; identification of specific characteristics or surrogate biomarkers of mutation status may lead to targeted treatment options.

Development of monoclonal antibodies against human CYP11B1 and CYP11B2

1. The final enzymes in the biosynthesis of aldosterone and cortisol are by the cytochrome P450 CYP11B2 and CYP11B1, respectively. The enzymes are 93% homologous at the amino acid level and specific antibodies have been difficult to generate. 2. Mice and rats were immunized with multiple peptides conjugated to various immunogenic proteins and monoclonal antibodies were generated. The only peptide sequences that generated specific antibodies were amino acids 41-52 for the CYP11B2 and amino acids 80-90 for the CYP11B1 enzyme. 3. The mouse monoclonal CYP11B2-41 was specific and sensitive for use in western blots and produced specific staining of the zona glomerulosa of normal adrenal glands. The rat monoclonal CYP11B1-80 also detected a single band by western blot and detected only the zona fasciculata. Triple immunofluorescence of the adrenal demonstrated that the CYP11B1 and the CYP11B2 did not co-localize, while as expected the CYP11B1 co-localized with the 17α-hydroxylase.

Cytochrome P450 11A1 bioactivation of a kinase inhibitor in rats: use of radioprofiling, modulation of metabolism, and adrenocortical cell lines to evaluate adrenal toxicity

A drug candidate, BMS-A ((N-(4-((1H-pyrrolo[2,3-b]pyridin-4-yl)oxy)-3-fluorophenyl)-1-(4-fluorophenyl) 2-oxo-1,2-dihydropyridine- 3-carboxamide)), was associated with dose- and time-dependent vacuolar degeneration and necrosis of the adrenal cortex following oral administration to rats. Pretreatment with 1-aminobenzotriazole (ABT), a nonspecific P450 inhibitor, ameliorated the toxicity. In vivo and in vitro systems, including adrenal cortex-derived cell lines, were used to study the mechanism responsible for the observed toxicity. Following an oral dose of the C-14 labeled compound, two hydroxylated metabolites of the parent (M2 and M3) were identified as prominent species found only in adrenal glands and testes, two steroidogenic organs. In addition, a high level of radioactivity was covalently bound to adrenal tissue proteins, 40% of which was localized in the mitochondrial fraction. ABT pretreatment reduced localization of radioactivity in the adrenal gland. Low levels of radioactivity bound to proteins were also observed in testes. Both M3 and covalent binding to proteins were found in incubations with mitochondrial fraction isolated from adrenal tissue in the presence of NADPH. In vitro formation of M3 and covalent binding to proteins were not affected by addition of GSH or a CYP11B1/2 inhibitor, metyrapone (MTY), but were inhibited by ketoconazole (KTZ) and a CYP11A1 inhibitor, R-(+)-aminoglutethimide (R-AGT). BMS-A induced apoptosis in a mouse adrenocortical cell line (Y-1) but not in a human cell line (H295R). Metabolite M3 and covalent binding to proteins were also produced in Y-1 and to a lesser extent in H295R cells. The cell toxicity, formation of M3, and covalent binding to proteins were all diminished by R-AGT but not by MTY. These results are consistent with a CYP11A1-mediated bioactivation to generate a reactive species, covalent binding to proteins, and subsequently rat adrenal toxicity. The thorough understanding of the metabolism-dependent adrenal toxicity was useful to evaluate cross-species adrenal toxicity potential of this compound and related analogues.

Familial or genetic primary aldosteronism and Gordon syndrome

Salt-sensitive forms of hypertension have received considerable renewed attention in recent years. This article focuses on 2 main forms of salt-sensitive hypertension (familial or genetic primary aldosteronism [PA] and Gordon syndrome) and the current state of knowledge regarding their genetic bases. The glucocorticoid-remediable form of familial PA (familial hyperaldosteronism type I) is dealt with only briefly because it is covered in depth elsewhere.

Progress in primary aldosteronism: present challenges and perspectives

Primary Aldosteronism (PA) is a disorder of the adrenal zona glomerulosa (ZG) in which aldosterone secretion is increased and is relatively autonomous of normal regulatory mechanisms. A recent conference in Munich organized by Prof. Reincke addressed advances and challenges related to the screening, diagnosis, and identification of uni- and bilateral involvement of the diseased adrenal of PA. Some infrequently addressed issues are described herein. We postulate that most cases of PA are due to the activation by unknown mechanisms of subset of cells resulting in the formation of a multiple foci or nodules of hyperactive zona glomerulosa cells. This implies that one or several yet unidentified stimuli can drive aldosterone overproduction, as well as the proliferation of aldosterone-producing cells. Current diagnostic procedures allow to determine whether inappropriate aldosterone production is driven by one or both adrenal glands and thus to establish optimal treatment.

ACTH-independent macronodular adrenal hyperplasia: imaging findings of a rare condition : A case report

Endogenous Cushing's syndrome is a relatively rare disease. Most cases being ACTH-dependent, ACTH-independent Cushing's syndrome (AICS) is an even rarer condition [15%-20%]. In more than 95% cases the cause of AICS is unilateral adrenal enlargement caused by adenoma or carcinoma. Bilateral adrenal disease is caused by primary pigmented nodular adrenal dysplasia (PPNAD) and ACTH-independent macro nodular hyperplasia (AIMAH). Only few case reports of the latter condition exist in the radiology literature, PPNAD being the commoner of two as the cause for AICS.

The Steroid Hormone Biosynthesis Pathway as a Target for Endocrine-Disrupting Chemicals

Various chemicals found in the human and wildlife environments have the potential to disrupt endocrine functions in exposed organisms. Increasingly, the enzymes involved in the steroid biosynthesis pathway are being recognized as important targets for the actions of various endocrine-disrupting chemicals. Interferences with steroid biosynthesis may result in impaired reproduction, alterations in (sexual) differentiation, growth, and development and the development of certain cancers. Steroid hormone synthesis is controlled by the activity of several highly substrate-selective cytochrome P450 enzymes and a number of steroid dehydrogenases and reductases. Particularly aromatase (CYP19), the enzyme that converts androgens to estrogens, has been the subject of studies into the mechanisms by which chemicals interfere with sex steroid hormone homeostasis and function, often related to (de)feminization and (de)masculinazation processes. Studies in vivo and in vitro have focussed on ovarian and testicular function, with less attention given to other steroidogenic organs, such as the adrenal cortex. This review aims to provide a comprehensive overview of the state of knowledge regarding the mechanisms by which chemicals interfere with the function of steroidogenic enzymes in various tissues and organisms. The endocrine toxicities and mechanisms of action related to steroidogenesis of a number of classes of drugs and environmental contaminants are discussed. In addition, several potential in vitro bioassays are reviewed for their usefulness as screening tools for the detection of chemicals that can interfere with steroidogenesis. Analysis of the currently scattered state of knowledge indicates that still relatively little is known about the underlying mechanisms of interference of chemicals with steroidogenesis and their potential toxicity in steroidogenic tissues, neither in humans nor in wildlife. Considerably more detailed and systematic research in this area of (endocrine) toxicology is required for a better understanding of risks to humans and wildlife.

Adrenal incidentaloma in pregnancy: clinical, molecular and immunohistochemical findings

Adrenal incidentalomas detected during pregnancy are very rare, and the natural history of these tumors during gestation is unknown. We report a case of a pregnant woman with an adrenal mass discovered serendipitously, who was followed-up during gestation and underwent adrenalectomy shortly after delivery. This allowed the evaluation of both the clinical outcome and the molecular/immunohistochemical correlates. Estrogens may indeed influence the function and proliferation of human adrenal cells, and a state of circulating estrogen excess can represent an in vivo model to test their effect on the adrenals. No evidence of adrenal change in morphology and function was found in our patient throughout pregnancy, as shown by adrenal ultrasound imaging and adrenal hormone measurements. Four months after delivery, the patient underwent laparoscopic right adrenalectomy, and pathologic analysis revealed a 2.7 cm benign adrenocortical adenoma. The diameter of the adrenal mass at ultrasonography correlated highly with post-partum mass diameter measured by abdominal computed tomography (CT). Quantitative expression of both ERalpha and ERbeta by real-time RT-PCR analysis and Western blotting findings did not differ among adenoma, normal adjacent adrenal and normal adrenal control tissues. This case of an adrenal incidentaloma discovered during pregnancy shows that a close observation with endocrine investigations and ultrasonography could be an appropriate approach, delaying the decision of surgical intervention after delivery. Estrogen receptor mRNA levels in the adrenal mass similar to those observed in normal adrenals suggest that estrogen oversecretion during pregnancy was not a risk factor for tumor progression.

Telomerase is not required for experimental tumorigenesis of human and bovine adrenocortical cells

Telomerase has often been thought to be essential for tumorigenesis of human cells. Adrenocortical cancers, like other cancers, typically have telomerase activity. We reinvestigated the requirement for telomerase in the conversion of normal human and bovine adrenocortical cells to cancer cells. When primary adrenocortical cells were transduced with retroviruses encoding SV40 large T antigen and Ha-RasG12V and immediately transplanted into immunodeficient mice they produced invasive and metastatic tumors. Cells had negligible telomerase activity before transplantation and after recovery from tumors. However, these tumors were not immortal and cells entered crisis, limiting further growth of the tumor as well as invasion and metastasis. Infection of these tumor cells with a retrovirus encoding hTERT restored growth in culture and restored the malignant properties of the cells in immunodeficient animals. These experiments differ from previous studies in which telomerase was found to be essential for tumorigenicity: 1) we used tissue reconstruction techniques for introduction of cells into host animals and 2) we infected primary cells with retroviruses and immediately transplanted them without drug selection.

CT and MR Imaging of the Adrenal Glands in ACTH-independent Cushing Syndrome

Adrenocorticotropic hormone (ACTH)-independent hypercortisolism accounts for 15%-20% of cases of Cushing syndrome and always arises from primary adrenal disease. Computed tomographic (CT) and magnetic resonance (MR) imaging findings in 37 patients with primary adrenal Cushing syndrome were analyzed and correlated with pathologic findings. Hyperfunctioning adenomas (n = 24), together with functioning carcinomas (n = 10), accounted for 92% of cases. Adenomas had a significantly smaller mean size (3.5 vs 14.5 cm) and lower mean unenhanced CT attenuation value (11 vs 28 HU) than did carcinomas. The presence of necrosis, hemorrhage, and calcification favored a diagnosis of carcinoma. Six of 10 carcinoma patients had metastases at presentation. Two adenomas were seen within a myelolipoma, which was recognized at both CT and MR imaging due to its fat content, and two adenomas were of uncertain malignant potential. Bilateral disease--primary pigmented nodular adrenal dysplasia (PPNAD) (n = 2) and ACTH-independent macronodular adrenal hyperplasia (AIMAH) (n = 1)--had characteristic imaging features. In PPNAD, multiple tiny (2-5-mm) nodules were visible bilaterally, with no overall glandular enlargement and normal intervening adrenal tissue. In AIMAH, both glands were grossly enlarged and contained nodules up to 3 cm in diameter. Familiarity with the range of imaging appearances of the adrenal glands in primary adrenal Cushing syndrome may help establish the underlying diagnosis.

Primary aldosteronism

Approaching the fiftieth year since its original description, primary aldosteronism is now thought to be the commonest potentially curable and specifically treatable form of hypertension. Correct identification of patients with primary aldosteronism requires that the effects of time of day, posture, dietary sodium intake, potassium levels and medications on levels of aldosterone and renin be carefully considered. Accurate elucidation of the subtype is essential for optimal treatment, and adrenal venous sampling is the only reliable means of differentiating aldosterone-producing adenoma from bilateral adrenal hyperplasia. With genetic testing already available for one inherited form, making more cumbersome biochemical testing for that subtype virtually obsolete and bringing about improvements in treatment approach, an intense search is underway for genetic mutations causing other, more common familial varieties of primary aldosteronism.

Mutations in CYP11B1 gene converting 11beta-hydroxylase into an aldosterone-producing enzyme are not present in aldosterone-producing adenomas

In the human adrenal cortex, cortisol and aldosterone are synthesized by the isozymes 11beta-hydroxylase and aldosterone synthase, respectively, encoded by the 93% identical CYP11B1 and CYP11B2 genes. In vitro mutagenesis of CYP11B1 complementary DNA, resulting in the replacement of CYP11B1 codons by those encoding the corresponding amino acid residues of CYP11B2 enzyme (exon 5, Ser288Gly; exon 6, Val320Ala), yields a complementary DNA encoding a mutant enzyme with an efficient aldosterone synthase activity. Identical somatic mutations in the CYP11B1 gene in vivo would produce a gene encoding an enzyme with C18 activity and that would preserve ACTH responsiveness due to the retained 5'-promoter in the mutated CYP11B1 gene. An ACTH-responsive aldosterone synthase activity of this type is commonly seen in patients with aldosterone-producing adenomas (APA). We examined the occurrence of mutations in exons 5 and 6 of the CYP11B1 gene in APA from 10 patients with primary aldosteronism. Patients were selected on preoperative evidence of a 50% or greater plasma aldosterone decrease after short term dexamethasone trial and no aldosterone response to upright posture. DNA from adenomas was amplified by PCR using two pairs of primers spanning the regions of CYP11B1 gene, i.e. exons 3-5 and exons 6-9, where mutations could be located. Targeted regions were screened for mutations by automated sequencing of PCR products. No point mutations of the CYP11B1 gene over the two regions examined were found in APA. This argues against involvement of mutations in the pathogenesis of ACTH-responsive APA.

Hormonal characteristics of primary aldosteronism due to unilateral adrenal hyperplasia

A case of unilateral adrenocortical hyperplasia is presented. A 46-year-old woman with a 7-year history of hypertension and a 1-year-history of hypokalemia was diagnosed with primary aldosteronism. Computed tomography, magnetic resonance imaging, venous sampling and adosterol scintigraphy exhibited a functioning left adrenal mass. The plasma aldosterone concentration increased markedly when furosemide with upright posture and either captopril or adrenocorticotropin were administered. Plasma renin activity was suppressed below the detectable range. Aldosterone secretion displayed a circadian rhythm and was not suppressed by dexamethasone administration. The resected left adrenal mass was pathologically diagnosed as adrenocortical nodular hyperplasia. Unilateral adrenal hyperplasia involving the zona glomerulosa rarely has been reported, with varying and incompletely characterized hormonal characteristics. This case report and literature review suggest unilateral adrenal hyperplasia as a rare cause of hyperaldosteronism with characteristics intermediate between idiopathic hyperaldosteronism and aldosterone-producing adrenocortical adenoma, resembling the functional features of the adenoma more closely.

Adrenocortical tumor in a patient with familial adenomatous polyposis: a case associated with a complete inactivating mutation of the APC gene and unusual histological features

Familial adenomatous polyposis (FAP) is an autosomal dominant hereditary disorder caused by a germline inactivating mutation of the adenomatous polyposis coli (APC) gene. Patients with FAP sometimes develop various extracolonic manifestations including adrenocortical neoplasms. We present a 14-year-old boy with FAP who had an adrenocortical tumor with atypical histopathologic features, ie, sex-cord-like differentiation. Immunohistochemical studies of adrenal 4 binding protein (Ad4BP) and steroidogenic enzymes showed the capacity of these tumor cells to produce steroids. Genetic analysis of the tumor disclosed a two-hit mutation in APC: a germline 5-base pair deletion accompanied by a loss of the normal allele. Because there were no reports of genetic alterations in adrenocortical tumors developed in FAP patients, we examined 10 sporadic adrenal tumors (four carcinomas and six adenomas) for mutations in APC. However, no mutations were found in these 10 sporadic adrenal tumors. These results suggest that mutation of APC is also responsible for some fraction of the adrenocortical tumors: the tumor in this case is included.

Cortisol production by aldosterone-producing adenomas in vitro

1. In vitro short-term production of cortisol by dispersed tumour and non-tumourous adrenal cortical cells was measured with and without added angiotensin II (AII) or adrenocorticotrophin (ACTH) in adrenals removed from five patients with primary aldosteronism. 2. Aldosterone-producing adenomas (APA) were classified as angiotensin responsive (AII-R) or angiotensin unresponsive (AII-U) based on pre-operative behaviour in vivo. 3. Cortisol was produced by both tumour and cortex in vitro without stimulation, and significantly more cortisol was generated by the cortex. 4. Addition of AII significantly increased cortisol production by both tumour and cortex to an equal extent. 5. Addition of ACTH also significantly increased cortisol production by both tumour and cortex, but tumours were more responsive than cortex. The response to ACTH exceeded the response to angiotensin in both tumour and cortex. 6. There was no obvious difference between AII-R and AII-U APA in terms of cortisol production.

[The role of adrenal gland x-ray computed tomography and scintigraphy using radiolabelled norcholesterol in the etiological diagnosis of primary hyperaldosteronism]

The major etiologies of primary aldosteronism are aldosterone-producing adrenal adenoma, requiring a surgical treatment, and bilateral hyperplasia, usually managed with medical therapy. We only report a retrospective study on 22 patients with primary aldosteronism diagnosed by clinical and usual biochemical tests. All the patients were explored by computed tomography scan (CT) and iodomethyl-norcholesterol scintigraphy. The purpose of this study was to compare the capacity of the two methods to differentiate adrenal adenoma and hyperplasia. The CT scan was more sensitive (sensitivity: 88%) compare to scintigraphy (sensitivity: 64%) for the diagnosis of adrenal adenoma. However, the scintigraphy was a useful tool to detect asymmetric macronodular adrenal hyperplasia. Therefore, the catheterisation of adrenal venous would be only necessary for a few cases. We conclude from this study and the literature review that CT scan and iodomethyl-norcholesterol scintigraphy are complementary and both useful to increase diagnostic reliability of primary aldosteronism.

Histological and biochemical distinctiveness of atypical aldosterone-producing adenomas responsive to upright posture and angiotensin

Fifteen patients with primary aldosteronism were classified as angiotensin II-unresponsive aldosterone-producing adenoma (AII-U APA, n = 9), or angiotensin II-responsive aldosterone-producing adenoma (AII-R APA, n = 6), based on the responsiveness of aldosterone to upright posture and to angiotensin II infusion. Lack of aldosterone response to angiotensin II infusion immediately postoperatively in the AII-R APA subtype was consistent with previous responsiveness residing solely within the adenoma. Cortisol levels in five of the six patients with AII-R APA failed to suppress normally with dexamethasone consistent with some autonomous production of cortisol by the adenoma. In contrast, cortisol levels suppressed normally during dexamethasone administration in all patients with AII-U APA. This biochemical distinction can be added to the previously described overproduction of 18-oxo cortisol in AII-U APA but not in AII-R APA. Histological examination of adenoma sections revealed predominantly (greater than or equal to 50%) zona fasciculata type cells in AII-U APA. In contrast, AII-R APA contained less than 20% zona fasciculata type. Thus, biochemical differences between AII-U APA and AII-R APA subtypes of primary aldosteronism may be due to underlying differences in cellular composition of the aldosterone-producing adenomas.

Inappropriate ACTH concentrations in two patients with functioning adrenocortical carcinoma

Two female patients with functioning adrenocortical carcinomas had plasma ACTH detectable by RIA at presentation. In both patients there was evidence for biological activity of ACTH. There was no evidence for an ectopic source of ACTH, nor for a pituitary tumour. Urinary steroid analysis showed patterns of multiple hormone secretion characteristic of adrenocortical carcinomas. The finding of detectable ACTH concentrations in a patient with Cushing's syndrome does not exclude the presence of an adrenocortical tumour.

Primary adrenal tumours--a ten-year experience

The experience of 31 patients with primary adrenal tumours seen in one teaching hospital over a 10-year period is reviewed. There were 10 patients who had benign cortical adenomas; 11 had adrenal cortical carcinomas, and 10 had phaeochromocytomas, one of which was malignant. During the review period, a primary adrenal mass was discovered in 5% of 2951 autopsies performed in the study institution. The diagnosis and management of these uncommon tumours is reviewed.