Pathogenesis of adrenocortical incidentalomas and genetic syndromes associated with adrenocortical neoplasms

Adrenal disorders in pregnancy, labour and postpartum - an overview

Adrenal disorders may manifest during pregnancy for the first time, or present from before pregnancy as either undiagnosed or diagnosed and treated. They may present as hormonal hypofunction or hyperfunction, or with mass effects or other non-endocrine effects. Adrenal disorders such as Cushing's syndrome, Addison's disease, pheochromocytoma, primary hyper-aldosteronism and adreno-cortical carcinoma are rare in pregnancy. Pregnancy presents special problems in the evaluation of the hypothalamic-pituitary-adrenal and renin-angiotensin-aldosterone axis as these undergoe major changes during pregnancy. Diagnosis is challenging as symptoms associated with pregnancy are also seen in adrenal diseases. A timely diagnosis and treatment is critical as these disorders can cause maternal and foetal morbidity and mortality. A high index of suspicion must be maintained as they can go unrecognised and untreated. An early diagnosis and treatment often improves outcomes. The aim of this article is to review the patho-physiology, clinical manifestation, diagnosis and management of various adrenal disorders during pregnancy.

Adrenocortical carcinoma in pregnancy: A diagnostic dilemma

Adrenocortical carcinoma is a rare disease. Additionally, in the case of coexisting pregnancy, there are diagnostic difficulties due to associated physiological hormonal changes as well as imaging limitations. Cushing's syndrome and virilization during pregnancy is a rare entity with few cases reported in the literature. Misdiagnosis is common as the syndrome may be easily confused with preeclampsia or gestational diabetes. We present the case of a 31-year-old pregnant woman with rapidly developing symptoms related to hormonally active adrenocortical cancer.

Gene expression profiling of childhood adrenocortical tumors

Pediatric adrenocortical tumors (ACT) are rare and often fatal malignancies; little is known regarding their etiology and biology. To provide additional insight into the nature of ACT, we determined the gene expression profiles of 24 pediatric tumors (five adenomas, 18 carcinomas, and one undetermined) and seven normal adrenal glands. Distinct patterns of gene expression, validated by quantitative real-time PCR and Western blot analysis, were identified that distinguish normal adrenal cortex from tumor. Differences in gene expression were also identified between adrenocortical adenomas and carcinomas. In addition, pediatric adrenocortical carcinomas were found to share similar patterns of gene expression when compared with those published for adult ACT. This study represents the first microarray analysis of childhood ACT. Our findings lay the groundwork for establishing gene expression profiles that may aid in the diagnosis and prognosis of pediatric ACT, and in the identification of signaling pathways that contribute to this disease.

Aging of the Human Adrenal Cortex

The most striking age-related change in the human adrenal cortex is the decline in secretion of dehydroepiandrosterone and its sulfate, steroids synthesized by the inner zone of the cortex, the zona reticularis. Because these steroids are of essentially unknown function, the importance of this age-related change is the subject of considerable debate. It is likely that the age-related change in these steroids results from loss of zona reticularis cells or impairment of their function. During aging, cumulative damage to the zona reticularis could occur through ischemia-related infarcts and other causes of cell death. Cellular senescence could contribute to a loss of the ability of the tissue to replace lost cells. In contrast, feedback mechanisms that regulate adrenocortical growth cause compensatory local tissue hyperplasias called nodules. The effect of imperfect repair of damage combined with compensatory overgrowth in the form of nodules leads to an increasingly abnormal tissue architecture.

The clinically inapparent adrenal mass: update in diagnosis and management

Clinically inapparent adrenal masses are incidentally detected after imaging studies conducted for reasons other than the evaluation of the adrenal glands. They have frequently been referred to as adrenal incidentalomas. In preparation for a National Institutes of Health State-of-the-Science Conference on this topic, extensive literature research, including Medline, BIOSIS, and Embase between 1966 and July 2002, as well as references of published metaanalyses and selected review articles identified more than 5400 citations. Based on 699 articles that were retrieved for further examination, we provide a comprehensive update of the diagnostic and therapeutic approaches focusing on endocrine and radiological features as well as surgical options. In addition, we present recent developments in the discovery of tumor markers, endocrine testing for subclinical disease including autonomous glucocorticoid hypersecretion and silent pheochromocytoma, novel imaging techniques, and minimally invasive surgery. Based on the statements of the conference, the available literature, and ongoing studies, our aim is to provide practical recommendations for the management of this common entity and to highlight areas for future studies and research.

[Non-secreting adrenal tumours]

This paper presents the clinical features, imaging methods and treatment of non-secreting adrenal tumours. Adrenal incidentalomas are especially discussed. The main histological types of adrenal non-secreting tumours are evoked. Therapeutic considerations are discussed.

Angiogenesis in endocrine tumors

Angiogenesis is the process of new blood vessel development from preexisting vasculature. Although vascular endothelium is usually quiescent in the adult, active angiogenesis has been shown to be an important process for new vessel formation, tumor growth, progression, and spread. The angiogenic phenotype depends on the balance of proangiogenic growth factors such as vascular endothelial growth factor (VEGF) and inhibitors, as well as interactions with the extracellular matrix, allowing for endothelial migration. Endocrine glands are typically vascular organs, and their blood supply is essential for normal function and tight control of hormone feedback loops. In addition to metabolic factors such as hypoxia, the process of angiogenesis is also regulated by hormonal changes such as increased estrogen, IGF-I, and TSH levels. By measuring microvascular density, differences in angiogenesis have been related to differences in tumor behavior, and similar techniques have been applied to both benign and malignant endocrine tumors with the aim of identification of tumors that subsequently behave in an aggressive fashion. In contrast to other tumor types, pituitary tumors are less vascular than normal pituitary tissue, although the mechanism for this observation is not known. A relationship between angiogenesis and tumor size, tumor invasiveness, and aggressiveness has been shown in some pituitary tumor types, but not in others. There are few reports on the role of microvascular density or angiogenic factors in adrenal tumors. The mechanism of the vascular tumors, which include adrenomedullary tumors, found in patients with Von Hippel Lindau disease has been well characterized, and clinical trials of antiangiogenic therapy are currently being performed in patients with Von Hippel Lindau disease. Thyroid tumors are more vascular than normal thyroid tissue, and there is a clear correlation between increased VEGF expression and more aggressive thyroid tumor behavior and metastasis. Although parathyroid tissue induces angiogenesis when autotransplanted and PTH regulates both VEGF and MMP expression, there are few studies of angiogenesis and angiogenic factors in parathyroid tumors. An understanding of the balance of angiogenesis in these vascular tumors and mechanisms of vascular control may assist in therapeutic decisions and allow appropriately targeted treatment.

Clinical and molecular aspects of adrenocortical tumourigenesis

Adrenal masses are a common problem affecting 3-7% of the population. The majority turn out to be benign adrenocortical adenomas, which may be functional or non-functional. Much more rarely, these masses represent a primary adrenal carcinoma. It is becoming increasingly recognized that of the benign functioning adenomas or hyperplasias, the majority will hypersecrete aldosterone and this will be more frequently detected when hypertensive populations are screened for this disease. In contrast, the incidence of primary adrenocortical carcinoma has remained steady and for this disease, surgery represents the mainstay of treatment. The advent of laparoscopic adrenal surgery has lowered the threshold size for recommending surgery for asymptomatic adrenal masses and as such, an increased proportion of adrenocortical cancers are being resected and detected at an earlier stage. Recent progress has been made in our understanding of the key genetic changes which underpin the biology of this disease. Progression from adrenal adenoma to carcinoma involves a monoclonal proliferation of cells which, among other defects, have undergone chromosomal duplication at the 11p15.5 locus leading to overexpression of the IGF2 gene and abrogation of expression of the CDKN1C and H19 genes. TP53 is involved in progression to carcinoma in a subset of patients and the frequency of ACTH receptor deletion needs to be more fully explored. Other key oncogenes and tumour suppressor genes remain to be identified although the chromosomal loci in which they lie can be identified at 17p, 1p, 2p16 and 11q13 for tumour suppressor genes and chromosomes 4, 5 and 12 for oncogenes.

Adrenal incidentaloma

Adrenal incidentalomas are incidentally discovered adrenal masses greater than 1 cm in diameter that appear to be clinically nonfunctioning. They are detected during imaging procedures of the abdomen and chest (CT, MRI, and ultrasonography) for an unrelated condition or symptom complex. With the widespread escalation in the use of these imaging modalities and marked improvements in image resolution, the probability of finding an incidentaloma on cross-section imaging is rapidly approaching the 6% prevalence of previously reported autopsy studies. All incidentalomas greater than 1 cm should be evaluated for hormonal activity, including a 1-mg overnight dexamethasone suppression test, total 24-hour urinary metanephrines and fractionated catecholamines, and, in the hypertensive patient, a serum potassium level and plasma aldosterone concentration to plasma renin activity ratio. All hormonally active tumors should be removed. Hormonally inactive tumors are resected based on size, imaging phenotype, and interval growth. Percutaneous biopsies are generally unwarranted and are potentially dangerous. Laparoscopic adrenalectomy has become the surgical procedure of choice for most benign functioning and nonfunctioning tumors of the adrenal gland. Subclinical metabolic abnormalities associated with adrenal incidentalomas remain an area of intense clinical research.

Benign Anatomical Mistakes: Incidentaloma

The concept of the “incidentaloma,” a totally asymptomatic nonfunctional tumor that is clinically and biochemically silent and discovered “incidentally” in a totally asymptomatic patient, is a by-product of the evolving diagnostic techniques of the last three decades. Various authors have used the concept for “incidental” findings during diagnostic workup for symptoms unrelated to adrenal disease, or for “incidental” adrenal tumors unrelated to symptoms that could potentially be of adrenal origin. “Incidentaloma” has been used to encompass a wide and heterogeneous spectrum of pathologic entities including adrenocortical and medullary tumors, benign or malignant lesions, hormonally active or inactive lesions, metastases, infections, granulomas, infiltrations, cysts and pseudocysts, hemorrhages, and pseudoadrenal masses. The term “incidentaloma” does not indicate whether the mass is functional, or malignant, or adrenocortical in origin. “Incidentaloma” has also appeared in the literature in reference to other endocrine organs such as pituitary, thyroid, and parathyroids, as well as the liver or kidney. We question the scientific justification for this neologism and suggest that it should be abolished. Questionable lesions should be clearly and simply described as “incidentally found.”

The adrenal incidentaloma: disease of modern technology and public health problem

The optimal strategy for evaluation of a patient with an incidentally discovered adrenal mass is unclear and remains controversial. A prospective multi-center randomized (or even non-randomized) trial would go a long way toward resolving the controversies. However, we lack such a study. Review of the literature supports the view that such patients are at somewhat increased risk of morbidity and mortality and this implies a benefit of early diagnosis for at least for some of the disorders. Our ability to accurately determine clinically those at increased risk among the vast majority who are not at increased risk is poor. We therefore rely on biochemical and radiological diagnostic tests, which have their own limitations. Subjecting patients to unnecessary testing and treatment carries its own set of risks. The diagnostic process itself may contribute considerable anxiety, expense, and if invasive cause pain and other morbidity. The harm that occurs as false positive results are pursued has been termed the "cascade effect" [34]. We must avoid the pitfalls of overestimation of disease prevalence and of the benefits of therapy resulting from advances in diagnostic imaging. In the meantime, we must use our best clinical judgement based upon the best available evidence to ensure that we maximize the benefit to those patients with AI who have clinically significant adrenal disorders and minimize the harm to those who do not.

The adrenal and the metabolic syndrome

This review discusses the possible interrelationships between adrenal steroid hormones and the metabolic syndrome. Abnormal regulation of the hypothalamic-pituitary-adrenal axis has been proposed. Studies in the United Kingdom associated the metabolic syndrome with low birth weight and hyperactivity of the entire axis. In Italy, increased pituitary responsiveness to stimulation with vasopressin and corticotrophin-releasing hormone was demonstrated in women with central obesity. Swedish researchers have reported that increased stress responses of the axis correlated with a less variable but decreased cortisol level. An allele of the glucocorticoid receptor was also associated with various components of the metabolic syndrome. Evidence also suggests that central obesity is associated with an increased peripheral conversion of cortisol to cortisone and subsequent feedback stimulation of the axis. On the other hand, central fat may have an increased local metabolism in the direction of cortisol. Roles for dehydroepiandrosterone and aldosterone in the syndrome have also been proposed.