Adrenal Masses: Contemporary Imaging Characterization

Primary bilateral macronodular adrenal hyperplasia: A series of 32 cases and literature review

Primary bilateral macronodular adrenal hyperplasia (PBMAH) accounts for <2% of cases of Cushing's syndrome. The majority of patients present with no obvious steroid excess it means with autonomous cortisol secretion (ACS). The classic treatment for patients with overt Cushing's syndrome is bilateral adrenalectomy, but unilateral resection of the larger adrenal gland can result in clinical and/or biochemical remission in >90% of cases, especially in cases of ACS. In this article, a series of 32 cases with PBMAH is described. Most of the cases of PBMAH had ACS, except for one case with overt Cushing's syndrome. A study of aberrant receptors was performed in six patients, being negative in three cases, positive in the metoclopramide test in two cases and positive in the metoclopramide test and in the mixed meal test in another patient. The patient with overt Cushing's syndrome was treated with adrenostatic therapy achieving biochemical control, while two patients with ACS underwent unilateral adrenalectomy with resection of the largest adrenal gland, demonstrating hypercortisolism remission and improvement of cardiovascular risk factors after surgery. This article describes a series of 32 cases of PBMAH and offers a comprehensive review of PBMAH.

Discriminative Capacity of CT Volumetry to Identify Autonomous Cortisol Secretion in Incidental Adrenal Adenomas

CONTEXT

Incidentally discovered adrenal adenomas are common. Assessment for possible autonomous cortisol excess (ACS) is warranted for all adrenal adenomas, given the association with increased cardiometabolic disease.

OBJECTIVE

To evaluate the discriminatory capacity of 3-dimensional volumetry on computed tomography (CT) to identify ACS.

METHODS

Two radiologists, blinded to hormonal levels, prospectively analyzed CT images of 149 adult patients with unilateral, incidentally discovered, adrenal adenomas. Diameter and volumetry of the adenoma, volumetry of the contralateral adrenal gland, and the adenoma volume-to-contralateral gland volume (AV/CV) ratio were measured. ACS was defined as cortisol ≥ 1.8 mcg/dL after 1-mg dexamethasone suppression test (DST) and a morning ACTH ≤ 15. pg/mL.

RESULTS

We observed that ACS was diagnosed in 35 (23.4%) patients. Cortisol post-DST was positively correlated with adenoma diameter and volume, and inversely correlated with contralateral adrenal gland volume. Cortisol post-DST was positively correlated with the AV/CV ratio (r = 0.46, P < 0.001) and ACTH was inversely correlated (r = -0.28, P < 0.001). The AV/CV ratio displayed the highest odds ratio (1.40; 95% CI, 1.18-1.65) and area under curve (0.91; 95% CI, 0.86-0.96) for predicting ACS. An AV/CV ratio ≥ 1 (48% of the cohort) had a sensitivity of 97% and a specificity of 70% to identify ACS.

CONCLUSION

CT volumetry of adrenal adenomas and contralateral adrenal glands has a high discriminatory capacity to identify ACS. The combination of this simple and low-cost radiological phenotyping can supplement biochemical testing to substantially improve the identification of ACS.

Pitfalls and differential diagnosis on adrenal lesions: current concepts in CT/MR imaging: a narrative review

The purpose of this pictorial essay is to review the imaging findings of adrenal lesions. Adrenal lesions could be divided into functioning or non-functioning masses, primary or metastatic, and benign or malignant. Imaging techniques have undergone significant advances in recent years. The most significant objective of adrenal imaging is represented by the detection and, when possible, characterization of adrenal lesions in order to direct patient management correctly. The detection and management of adrenal lesions is based on cross-sectional imaging obtained with non-contrast CT (tumour density), contrast-enhanced CT including delayed washout (either absolute percentage washout or relative percentage one) and finally with MR chemical shift analysis (loss of signal intensity between in-phase and out-of-phase images including both qualitative and quantitative estimates of signal loss). The small incidental adrenal nodules are benign, in most of cases; some tumors such as lipid-rich adenoma and myelolipoma have characteristic features that can be diagnosed accurately in CT. On contrary, if the presenting contrast-enhanced CT shows an adrenal mass with uncertain or malignant morphologic features, particularly in patients with a known history of malignancy, further evaluations should be considered. The most significative implications for radiologists are represented by how to assess risk of malignancy on imaging and what follow-up to indicate if an adrenal incidentaloma is not surgically removed.

Approach to patients with bilateral adrenal incidentalomas

PURPOSE OF REVIEW

The current review provides a summary on the most recent developments regarding the cause, work-up and management of bilateral adrenal incidentalomas (BAI).

RECENT FINDINGS

The recent ENS@T/ESE guidelines provide comprehensive directions on the evaluation and management of patients with adrenal incidentalomas with special focus on those with bilateral tumours. Intraadrenal ACTH synthesis that may locally stimulate cortisol secretion challenging the traditionally used term 'ACTH-independent'. Inactivating mutations of a new tumour suppressor gene, armadillo repeat containing 5 (ARMC5), are implicated in a number of patients, especially those with multiple macronodules (bilateral macronodular hyperplasia) and evidence of hypercortisolism. Loss-of-function mutations of the glucocorticoid receptor gene (NR3C1) consist a new possible genetic cause of BAIs. Regarding management an increasing number of studies provide data on the benefits and safety of unilateral rather than bilateral adrenalectomy. There is also emerging data on the beneficial use of steroidogenesis inhibitors in a dosing schedule that aims to mimic the normal cortisol rhythm with promising short-term results, but the long-term clinical benefits of this approach remain to be demonstrated.

SUMMARY

The diagnostic approach consists of imaging and hormonal evaluation. Imaging characterization should be done separately for each lesion. Hormonal evaluation includes testing for primary aldosteronism, pheochromocytoma and evaluation for autonomous cortisol secretion, using the 1-mg overnight dexamethasone suppression test. Midnight cortisol or 24-h urinary-free cortisol may aid in establishing the degree of cortisol excess. In patients with hypercortisolism ACTH levels should be measured to establish ACTH-independency. The appropriate management of BAI associated with cortisol excess remains controversial. Bilateral adrenalectomy results in lifetime steroid dependency and is better reserved only for patients with overt and severe hypercortisolism. Unilateral adrenalectomy might be considered in selected patients. Medical therapy is not an established approach yet but it may be considered when control of hypercortisolism is desired, but surgery is not an option.

A pictorial review of non-traumatic adrenergic crisis

Non-traumatic adrenal crisis is a rare but critical diagnosis to make in emergency settings due to grave consequences. Various pathologies can present as acute crisis, such as spectrum of endocrine imbalance, ranging from catecholamine excess in pheochromocytomas to acute adrenal insufficiency related to glandular dysfunction. Critical manifestations may be due to structural causes related to adrenal hemorrhage, especially when they are bilateral. Oncological complications such as vascular invasion, tumoral bleed, rupture, and hormonal dysfunction can occur. Due to non-specific clinical presentation, these conditions may come as a surprise on imaging performed for other reasons. Recognition of these imaging findings is critical for appropriate patient management. Although there are few articles discussing non-traumatic emergencies in literature, this review is inclusive of all possible etiologies, thus provides a holistic approach and insight into each situation. Specific imaging approach is needed to tailor the diagnosis. This article will also discuss about the advanced imaging techniques that will complement diagnosis.

Interobserver agreement in distinguishing large adrenal adenomas and adrenocortical carcinomas on computed tomography

PURPOSE

Large adrenal masses pose a diagnostic dilemma. The purpose of this study was twofold: first, to assess the degree of interobserver agreement in evaluating the morphology of pathologically proven adrenal adenomas and adrenocortical carcinomas larger than 4 cm in diameter; and second, to identify morphologic characteristics that correlated with the pathologic diagnosis.

MATERIALS AND METHODS

For this blinded, retrospective study, we collected cases of 25 adrenal adenomas and 33 adrenocortical carcinomas measuring larger than 4 cm. Two radiologists evaluated morphologic characteristics of the lesions on CT. Interobserver agreement was evaluated using kappa statistics, and the correlation of imaging characteristics with the diagnosis was evaluated using a logistic regression model.

RESULTS

We found the highest interobserver agreement in the assessment of precontrast attenuation (Κ = 0.81) as well as substantial agreement in determining the shape and the presence of calcifications (Κ = 0.69 and 0.74, respectively). Readers agreed less often regarding the presence of fat (Κ = 0.48), as well as regarding the presence of necrosis, heterogeneity, and the overall impression (Κ = 0.15, 0.24, and 0.26, respectively). CT characteristics correlated with benignity included round shape (p = 0.02), an overall radiologic impression of a benign lesion (p < 0.0001), the presence of fat (p = 0.01), and a precontrast attenuation of less than 10 Hounsfield units (p < 0.0001). The latter two of these characteristics were highly specific for benign pathology (93% and 100%, respectively).

CONCLUSION

Our study suggests that CT has the ability to consistently identify characteristics significantly correlated with benign vs. malignant adrenal tumors.

MANAGEMENT OF ENDOCRINE DISEASE: Differential diagnosis, investigation and therapy of bilateral adrenal incidentalomas

The investigation and management of unilateral adrenal incidentalomas have been extensively considered in the last decades. While bilateral adrenal incidentalomas represent about 15% of adrenal incidentalomas (AIs), they have been less frequently discussed. The differential diagnosis of bilateral incidentalomas includes metastasis, primary bilateral macronodular adrenal hyperplasia and bilateral cortical adenomas. Less frequent etiologies are bilateral pheochromocytomas, congenital adrenal hyperplasia (CAH), Cushing's disease or ectopic ACTH secretion with secondary bilateral adrenal hyperplasia, primary malignancies, myelolipomas, infections or hemorrhage. The investigation of bilateral incidentalomas includes the same hormonal evaluation to exclude excess hormone secretion as recommended in unilateral AI, but diagnosis of CAH and adrenal insufficiency should also be excluded. This review is focused on the differential diagnosis, investigation and treatment of bilateral AIs.

Contrast-Enhanced Computed Tomography in Intensive Care Unit Patients With Acute Clinical Deterioration: Impact of Hyperattenuating Adrenal Glands

PURPOSE

The study sought to assess the frequency and prognostic value of hyperattenuating adrenal glands on contrast-enhanced computed tomography (CT) scans of surgical intensive care unit (ICU) patients with acute clinical deterioration.

METHODS

Eighty-eight consecutive ICU patients (63.2 ± 14.5 years of age) were included in this retrospective analysis. All patients underwent biphasic contrast-enhanced CT due to an acute clinical deterioration. Hyperattenuation of the adrenal glands was assessed subjectively and objectively. Subjective presence or absence of hyperattenuating adrenal glands was assessed by 2 blinded radiologists (J.B. and R.S.L.) in consensus. Hounsfield units (HU) were measured in the adrenal glands and in the inferior vena cava. Objective hyperattenuation was defined as HU (adrenal glands) > HU (inferior vena cava) with a 15-HU threshold. Death within 14 days following CT was set as endpoint and acquired from electronic patient data.

RESULTS

Thirty-eight patients (43.2%, Group A_subj) exhibited hyperattenuation of the adrenal glands, whereas 50 patients (56.8%, Group B_subj) did not. Concerning the objective analysis, 31 patients (35.2%, Group A_obj) exhibited hyperdense adrenal glands, whereas 53 patients (64.8%, Group B_obj) did not. Overall 27 of 88 patients (30.6%) died within 14 days following the CT examination. Lethal outcome was significantly more frequent among patients in Group A_subj and A_obj (19 of 38 patients [50.0%] and 15 of 31 patients [48.4%]) as compared with patients in Group B_subj (8 of 50 patients [16.0%]) and Group B_obj (12 of 57 patients [21.1%]; P < .05). Subjective and objective analysis correlated significantly (P < .05).

CONCLUSIONS

Hyperattenuation of adrenal glands on contrast-enhanced CT of ICU patients with acute clinical deterioration is associated with a high mortality and might serve as a prognostic marker for patients' outcome.

Imaging Features of Various Adrenal Neoplastic Lesions on Radiologic and Nuclear Medicine Imaging

OBJECTIVE

The purpose of this review is to describe the features of diverse adrenal neoplastic lesions on radiologic and nuclear medicine imaging.

CONCLUSION

Various neoplastic lesions with or without malignant potential can occur in the adrenal gland. Knowledge of imaging features of adrenal lesions on radiologic and nuclear medicine imaging will facilitate differential diagnosis and assessment of malignant potential.

[Adrenal tumors: principles of imaging and differential diagnostics]

CLINICAL/METHODICAL ISSUE

Adrenal masses are very common and are usually detected incidentally. Less frequently, imaging is performed for the localization of the underlying lesion in the case of endocrine disease. The differentiation between adenomas and non-adenomas is fundamental.

METHODICAL INNOVATIONS

Adenomas show a low density on unenhanced computed tomography (CT) and a rapid washout of contrast agents. In magnetic resonance imaging (MRI) adenomas are characterized by a low signal in opposed phase imaging as compared to in phase imaging.

PERFORMANCE

According to the literature a density of less than 10 HU in an adrenal mass has a specificity of 98% and a sensitivity of 71% for the presence of an adenoma and MRI is slightly more sensitive. Some adrenal lesions, e.g. cysts or myelolipomas can be diagnosed with high accuracy due to pathognomonic findings.

ACHIEVEMENTS

In the majority of cases the synopsis of imaging along with clinical and laboratory findings is necessary for a reliable diagnosis.

PRACTICAL RECOMMENDATIONS

For the evaluation of an adrenal mass the CT examination should begin with an unenhanced scan, if necessary followed by a washout examination. In the case of MRI in phase and opposed phase imaging are essential components of the examination.

Primary bilateral macronodular adrenal hyperplasia

PURPOSE OF REVIEW

Primary bilateral macronodular adrenal hyperplasia is a rare cause of Cushing's syndrome and is more often diagnosed as bilateral adrenal incidentalomas with subclinical cortisol production. We summarize the recent insights concerning its epidemiology, diagnosis, genetics, pathophysiology, and therapeutic options.

RECENT FINDINGS

Recent publications have modified our notions on the genetics and pathophysiology of bilateral macronodular adrenal hyperplasia. Combined germline and somatic mutations of armadillo repeat containing 5 gene were identified in familial cases, in approximately 50% of apparently sporadic cases and in the relatives of index cases; genetic testing should allow early diagnosis in the near future. The recent finding of ectopic adrenocortical production of adrenocorticotropic hormone in clusters of bilateral macronodular adrenal hyperplasia tissues and its regulation by aberrant hormone receptors opens new horizons for eventual medical therapy using melanocortin-2 receptor and G-protein-coupled receptor antagonists. Finally, some medical and surgical treatments have been updated.

SUMMARY

Recent findings indicate that bilateral macronodular adrenal hyperplasia is more frequently genetically determined than previously believed. Considering the role of paracrine adrenocorticotropic hormone production on cortisol secretion, the previous nomenclature of adrenocorticotropic hormone-independent macronodular adrenal hyperplasia appears inappropriate, and this disease should now be named primary bilateral macronodular adrenal hyperplasia.