Volumetric Modeling of Adrenal Gland Size in Primary Bilateral Macronodular Adrenocortical Hyperplasia

Advancements in the research of the structure, function, and disease-related roles of ARMC5

The armadillo repeat containing 5 (ARMC5) gene is part of a family of protein-coding genes that are rich in armadillo repeat sequences, are ubiquitously present in eukaryotes, and mediate interactions between proteins, playing roles in various cellular processes. Current research has demonstrated that reduced expression or absence of the ARMC5 gene in various tumor tissues can lead to uncontrolled cell proliferation, thereby inducing a range of diseases. The ARMC5 gene was initially extensively studied in the context of bilateral macronodular adrenocortical disease (BMAD), with harmful pathogenic variants in ARMC5 identified in approximately 50% of BMAD patients. With advancing research, scientists have discovered that ARMC5 pathogenic variants may also have potential effects on other diseases and could be associated with increased susceptibility to certain cancers. This review aims to present the latest research progress on how the ARMC5 gene plays its role in tumors. It outlines the basic structure of ARMC5 and the regions where it functions, as well as the diseases currently proven to be associated with ARMC5. Moreover, some evidence suggests its relation to embryonic development and the regulation of immune system activity. In conclusion, the ARMC5 gene is a crucial focal point in genetic and medical research. Understanding its function and regulation is of great importance for the development of new therapeutic strategies related to diseases associated with its pathogenic variants.

Prevalence and main characteristics of primary aldosteronism in bilateral macronodular adrenal disease: a systematic review of the literature

CONTEXT

Bilateral macronodular adrenal disease (BMAD) typically presents with bilateral benign adrenocortical macronodules and variable cortisol excess. Anecdotal evidence suggests oversecretion of other adrenal steroids, including mineralocorticoids.

HYPOTHESIS

We hypothesized that primary aldosteronism (PA) can occur in BMAD, resulting in a distinct, more severe phenotype compared to BMAD with isolated cortisol hypersecretion or unilateral PA (uPA).

OBJECTIVE

To assess the prevalence and characteristics of PA in BMAD.

METHODS

We systematically reviewed case reports and series of BMAD patients with PA, following PRISMA guidelines. BMAD was defined by bilateral adrenal nodules ≥10 mm. PA diagnosis followed US or Japanese Endocrine Society guidelines. We compared these findings with 2 cohorts from LMU Hospital Munich: BMAD with isolated cortisol hypersecretion and uPA.

RESULTS

From 1018 articles, 18 representing 68 cases were included. Of these, 66 had BMAD with PA and 2 had BMAD with aldosterone precursor excess. The PA proportion in published BMAD series ranged from 2% to 43%. BMAD patients with PA were predominantly male (75%) and younger (median 51.5 years) than those with isolated cortisol hypersecretion (median 60.5 years, P < .01). Their median blood pressure was higher (170/100 mm Hg) compared to those with isolated cortisol hypersecretion (138/80 mm Hg) or uPA (153/94 mm Hg, P < .01). Treatment was only described in 28 cases, with 93% undergoing adrenalectomy. Clinical outcome was similar across groups post-treatment.

CONCLUSION

This review highlights the need for increased screening for PA in younger, hypertensive BMAD patients. Larger multicenter studies are needed to determine the association between these conditions, cardiovascular risk, and optimal treatment.

Bilateral macronodular adrenocortical disease: a single centre experience

Background

Data on bilateral macronodular adrenocortical disease (BMAD) with respect to computed tomography (CT) scan characteristics (attenuation and washout) and long-term follow-up are limited. This study aims to describe BMAD patients managed in a single centre.

Methods

BMAD was defined by the presence of bilateral adrenal macronodules (>1 cm) on CT. Clinical, biochemical, radiological, genetic characteristics, management and follow-up of 22 BMAD patients were studied retrospectively.

Results

The median age (range) at presentation was 49.5 (23-83) years, predominantly observed in females (16/22). Eighteen (82%) patients were incidentally diagnosed (11 with mild autonomous cortisol secretion (MACS) and seven non-secretory), three (13.7%) presented with overt Cushing's syndrome (CS), and one (4.5%) had androgen excess (without CS features). On CT, the dominant nodule's median (range) size was 2.6(1.6-9.5) cm. 77.8% (14/18) of adrenal nodules were lipid-rich, and 93.3% (14/15) of the nodules exhibited good washout. Genetic analysis was available for eight patients; one had a novel germline ARMC5 variant, and two had MEN-1 gene mutations. Three overt CS and one androgen-secreting patient underwent total bilateral adrenalectomy; histopathology showed macronodular hyperplasia with internodular hypertrophy. Only one (1/8) patient from the MACS group developed a new comorbidity (diabetes mellitus) after a median follow-up of 6.4 (0.5-12.4) years, while none of the non-secretory group patients developed new comorbidities after a median follow-up of 1.4 (0.8-12.2) years.

Conclusion

Most BMAD patients presented without overt hormonal excess, and none developed overt CS on follow-up. Detailed CT characteristics of BMAD nodules may help in radiological diagnosis in bilateral adrenal incidentalomas.

The mutational landscape of ARMC5 in Primary Bilateral Macronodular Adrenal Hyperplasia: an update

BACKGROUND

Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH) is a rare cause of Cushing's syndrome due to bilateral adrenocortical macronodules. Germline inactivating variants of the tumor suppressor gene ARMC5 are responsible for 20-25% of apparently sporadic PBMAH cases and 80% of familial presentations. ARMC5 screening is now routinely performed for PBMAH patients and families. Based on literature review and own observation, this study aims to give an overview of both published and unpublished ARMC5 genetic alterations and to compile the available evidence to discriminate pathogenic from benign variants.

RESULTS

146 different germline variants (110 previously published and 36 novel) are identified, including 46% missense substitutions, 45% truncating variants, 3% affecting splice sites, 4% in-frame variants and 2% large deletions. In addition to the germline events, somatic 16p loss-of-heterozygosity and 104 different somatic events are described. The pathogenicity of ARMC5 variants is established on the basis of their frequency in the general population, in silico predictions, familial segregation and tumor DNA sequencing.

CONCLUSIONS

This is the first extensive review of ARMC5 pathogenic variants. It shows that they are spread on the whole coding sequence. This is a valuable resource for genetic investigations of PBMAH and will help the interpretation of new missense substitutions that are continuously identified.

Clinical Review: The Approach to the Evaluation and Management of Bilateral Adrenal Masses

OBJECTIVE

This white paper provides practical guidance for clinicians encountering bilateral adrenal masses.

METHODS

A case-based approach to the evaluation and management of bilateral adrenal masses. Specific clinical scenarios presented here include cases of bilateral adrenal adenomas, hemorrhage, pheochromocytomas, metastatic disease, myelolipomas, as well as primary bilateral macronodular adrenal hyperplasia.

RESULTS

Bilateral adrenal masses represent approximately 10% to 20% of incidentally discovered adrenal masses. The general approach to the evaluation and management of bilateral adrenal masses follows the same protocol as the evaluation of unilateral adrenal masses, determined based on the patient's clinical history and examination as well as the imaging characteristics of each lesion, whether the lesions could represent a malignancy, demonstrate hormone excess, or possibly represent a familial syndrome. Furthermore, there are features unique to bilateral adrenal masses that must be considered, including the differential diagnosis, the evaluation, and the management depending on the etiology. Therefore, considerations for the optimal imaging modality, treatment (medical vs surgical therapy), and surveillance are included. These recommendations were developed through careful examination of existing published studies as well as expert clinical opinion consensus.

CONCLUSION

The evaluation and management of bilateral adrenal masses require a comprehensive systematic approach which includes the assessment and interpretation of the patient's clinical history, physical examination, dynamic hormone evaluation, and imaging modalities to determine the key radiographic features of each adrenal nodule. In addition, familial syndromes should be considered. Any final treatment options and approaches should always be considered individually.

Defining sexual dimorphism in masculinizing chest surgery using 3-dimensional imaging

There is no consensus on the ideal scar location and inframammary fold (IMF) placement in the gender-affirming double-incision mastectomy technique. Recent advances in imaging technology have facilitated noninvasive investigations into anatomic variability, in many cases, obviating the traditional approach of cadaveric dissection to answer anatomic questions. A better understanding of chest wall sexual dimorphism may allow surgeons who perform gender-affirming procedures to achieve more natural-appearing results. A total of 60 chests were analyzed using either cadaveric dissection (n = 30) or virtual dissection with 3-dimensional (3-D) reconstructions of computed tomography (CT) images (n = 30) using the Vitrea® software. Chest proportions were recorded using each technique, correlating surface anatomy with muscular and bony landmarks. Cadaveric and 3-D radiography chest analysis revealed that natal male chest walls are, on average, wider and longer than natal female chest walls. The pectoralis major muscle dimensions and the location of its insertion were not found to significantly differ between male and female chests. The male nipple-areolar complex (NAC) tended to be narrower in length and width, with a less projecting nipple than the female NAC. Finally, the IMF was found to lie over the interspace between the fifth and sixth rib in both male and female chests. Our findings confirm natal male and female IMF are positioned between the 5th and 6th ribs. This fact affirms the senior author's technique of masculinizing the chest, keeping the masculinized IMF at approximately the same level as the natal female IMF and following the pectoralis major muscle edges to define the resulting scar in a way that differs from previously reported techniques.

Age-related morphometrics of normal adrenal glands based on deep learning-aided segmentation

OBJECTIVE

This study aims to evaluate the morphometrics of normal adrenal glands in adult patients semiautomatically using a deep learning-based segmentation model.

MATERIALS AND METHODS

A total of 520 abdominal CT image series with normal findings, from January 1, 2016, to March 14, 2019, were retrospectively collected for the training of the adrenal segmentation model. Then, 1043 portal venous phase image series of inpatient contrast-enhanced abdominal CT examinations with normal adrenal glands were included for analysis and grouped by every 10-year gap. A 3D U-Net-based segmentation model was used to predict bilateral adrenal labels followed by manual modification of labels as appropriate. Quantitative parameters (volume, CT value, and diameters) of the bilateral adrenal glands were then analyzed.

RESULTS

In the study cohort aged 18-77 years old (554 males and 489 females), the left adrenal gland was significantly larger than the right adrenal gland [all patients, 2867.79 (2317.11-3499.89) mm³ vs. 2452.84 (1983.50-2935.18) mm³, P < 0.001]. Male patients showed a greater volume of bilateral adrenal glands than females in all age groups (all patients, left: 3237.83 ± 930.21 mm³ vs. 2646.49 ± 766.42 mm³, P < 0.001; right: 2731.69 ± 789.19 mm³ vs. 2266.18 ± 632.97 mm³, P = 0.001). Bilateral adrenal volume in male patients showed an increasing then decreasing trend as age increased that peaked at 38-47 years old (left: 3416.01 ± 886.21 mm³, right: 2855.04 ± 774.57 mm³).

CONCLUSIONS

The semiautomated measurement revealed that the adrenal volume differs as age increases. Male patients aged 38-47 years old have a peaked adrenal volume.

Fully automatic volume measurement of the adrenal gland on CT using deep learning to classify adrenal hyperplasia

OBJECTIVES

To develop a fully automated deep learning model for adrenal segmentation and to evaluate its performance in classifying adrenal hyperplasia.

METHODS

This retrospective study evaluated automated adrenal segmentation in 308 abdominal CT scans from 48 patients with adrenal hyperplasia and 260 patients with normal glands from 2010 to 2021 (mean age, 42 years; 156 women). The dataset was split into training, validation, and test sets at a ratio of 6:2:2. Contrast-enhanced CT images and manually drawn adrenal gland masks were used to develop a U-Net-based segmentation model. Predicted adrenal volumes were obtained by fivefold splitting of the dataset without overlapping the test set. Adrenal volumes and anthropometric parameters (height, weight, and sex) were utilized to develop an algorithm to classify adrenal hyperplasia, using multilayer perceptron, support vector classification, a random forest classifier, and a decision tree classifier. To measure the performance of the developed model, the dice coefficient and intraclass correlation coefficient (ICC) were used for segmentation, and area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity were used for classification.

RESULTS

The model for segmenting adrenal glands achieved a Dice coefficient of 0.7009 for 308 cases and an ICC of 0.91 (95% CI, 0.90-0.93) for adrenal volume. The models for classifying hyperplasia had the following results: AUC, 0.98-0.99; accuracy, 0.948-0.961; sensitivity, 0.750-0.813; and specificity, 0.973-1.000.

CONCLUSION

The proposed segmentation algorithm can accurately segment the adrenal glands on CT scans and may help clinicians identify possible cases of adrenal hyperplasia.

KEY POINTS

• A deep learning segmentation method can accurately segment the adrenal gland, which is a small organ, on CT scans. • The machine learning algorithm to classify adrenal hyperplasia using adrenal volume and anthropometric parameters (height, weight, and sex) showed good performance. • The proposed segmentation algorithm may help clinicians identify possible cases of adrenal hyperplasia.

Clinical, pathophysiologic, genetic and therapeutic progress in Primary Bilateral Macronodular Adrenal Hyperplasia

Patients with primary bilateral macronodular adrenal hyperplasia (PBMAH) usually present bilateral benign adrenocortical macronodules at imaging and variable levels of cortisol excess. PBMAH is a rare cause of primary overt Cushing's syndrome, but may represent up to one third of bilateral adrenal incidentalomas with evidence of cortisol excess. The increased steroidogenesis in PBMAH is often regulated by various G-protein coupled receptors aberrantly expressed in PBMAH tissues; some receptor ligands are ectopically produced in PBMAH tissues creating aberrant autocrine/paracrine regulation of steroidogenesis. The bilateral nature of PBMAH and familial aggregation, led to the identification of germline heterozygous inactivating mutations of the ARMC5 gene, in 20-25% of the apparent sporadic cases and more frequently in familial cases; ARMC5 mutations/pathogenic variants can be associated with meningiomas. More recently, combined germline mutations/pathogenic variants and somatic events inactivating the KDM1A gene were specifically identified in patients affected by GIP-dependent PBMAH. Functional studies demonstrated that inactivation of KDM1A leads to GIP-receptor (GIPR) overexpression and over or down-regulation of other GPCRs. Genetic analysis is now available for early detection of family members of index cases with PBMAH carrying identified germline pathogenic variants. Detailed biochemical, imaging, and co-morbidities assessment of the nature and severity of PBMAH is essential for its management. Treatment is reserved for patients with overt or mild cortisol/aldosterone or other steroid excesses taking in account co-morbidities. It previously relied on bilateral adrenalectomy; however recent studies tend to favor unilateral adrenalectomy, or less frequently, medical treatment with cortisol synthesis inhibitors or specific blockers of aberrant GPCR.

Pathophysiology and histopathology of primary aldosteronism

Primary aldosteronism (PA) can be sporadic or familial and classified into unilateral and bilateral forms. Sporadic PA predominates with excessive aldosterone production usually arising from a unilateral aldosterone-producing adenoma (APA) or bilateral adrenocortical hyperplasia. Familial PA is rare and caused by germline variants, that partly correspond to somatic alterations in APAs. Classification into unilateral and bilateral PA determines the treatment approach but does not accurately mirror disease pathology. Some evidence indicates a disease continuum ranging from balanced aldosterone production from each adrenal to extreme asymmetrical bilateral aldosterone production. Nonetheless, surgical removal of the overactive adrenal in unilateral PA achieves highly successful outcomes and almost all patients are biochemically cured of their aldosteronism.

Steroid profiling using liquid chromatography mass spectrometry during adrenal vein sampling in patients with primary bilateral macronodular adrenocortical hyperplasia

INTRODUCTION

Adrenal vein sampling (AVS) is not a routine procedure in patients with primary bilateral macronodular adrenocortical hyperplasia (PBMAH), but has been used to determine lateralization of cortisol secretion in order to guide decision of unilateral adrenalectomy. Our aim was to characterize the steroid fingerprints in AVS samples of patients with PBMAH and hypercortisolism and to identify a reference hormone for AVS interpretation.

METHOD

Retrospectively, we included 17 patients with PBMAH from the German Cushing's registry who underwent AVS. 15 steroids were quantified in AVS and peripheral blood samples using LC-MS/MS. We calculated lateralization indices and conversion ratios indicative of steroidogenic enzyme activity to elucidate differences between individual adrenal steroidomes and in steroidogenic pathways.

RESULTS

Adrenal volume was negatively correlated with peripheral cortisone (r=0.62, p<0.05). 24-hour urinary free cortisol correlated positively with peripheral androgens (rDHEA=0.57, rDHEAS=0.82, rA=0.73, rT=0.54, p<0.05). DHEA was found to be a powerful reference hormone with high selectivity index, which did not correlate with serume cortisol and has a short half-life. All investigated steroids showed lateralization in single patients indicating the heterogenous steroid secretion pattern in patients with PBMAH. The ratios of corticosterone/aldosterone (catalyzed by CYP11B2), androstenedione/dehydroepiandrosterone (catalyzed by HSD3B2) and cortisone/cortisol (catalyzed by HSD11B2) in adrenal vein samples were higher in smaller adrenals (p<0.05). ARMC5 mutation carriers (n=6) showed lower androstenedione/17-hydroxyprogesterone and higher testosterone/androstenedione (p<0.05) ratios in peripheral blood, in line with lower peripheral androstenedione concentrations (p<0.05).

CONCLUSION

Steroid profiling by LC-MS/MS led us to select DHEA as a candidate reference hormone for cortisol secretion. Lateralization and different steroid ratios showed that each steroid and all three steroidogenic pathways may be affected in PBMAH patients. In patients with germline ARMC5 mutations, the androgen pathway was particularly dysregulated.

Bilateral Adrenal Hyperplasia: Pathogenesis and Treatment

Bilateral adrenal hyperplasia is a rare cause of Cushing’s syndrome. Micronodular adrenal hyperplasia, including the primary pigmented micronodular adrenal dysplasia (PPNAD) and the isolated micronodular adrenal hyperplasia (iMAD), can be distinguished from the primary bilateral macronodular adrenal hyperplasia (PBMAH) according to the size of the nodules. They both lead to overt or subclinical CS. In the latter case, PPNAD is usually diagnosed after a systematic screening in patients presenting with Carney complex, while for PBMAH, the diagnosis is often incidental on imaging. Identification of causal genes and genetic counseling also help in the diagnoses. This review discusses the last decades’ findings on genetic and molecular causes of bilateral adrenal hyperplasia, including the several mechanisms altering the PKA pathway, the recent discovery of ARMC5, and the role of the adrenal paracrine regulation. Finally, the treatment of bilateral adrenal hyperplasia will be discussed, focusing on current data on unilateral adrenalectomy.