The discriminatory value of the low-dose dexamethasone suppression test in the investigation of paediatric Cushing's syndrome

Paediatric and adolescent ectopic Cushing's syndrome: systematic review

OBJECTIVE

The data on clinical, biochemical, radiological characteristics, and outcomes in paediatric ectopic adrenocorticotropic hormone syndrome (EAS) are limited owing to rarity of the condition. We report three new cases and perform a systematic review of paediatric EAS.

DESIGN AND METHOD

Case records of paediatric and adolescent EAS patient's ≤20 years presenting at our centre between 1997 and 2021 were retrospectively reviewed, and a systematic review of the literature published between January 1970 and December 2022 was performed.

RESULTS

A total of 161 patients including 3 new patients from our centre were identified. Bronchial neuroendocrine tumours (NET) (28.5%), thymic NET (22.9%), primitive cell-derived tumours (18.6%), and gastro-entero-pancreatic-NET (13.7%) were the common causes. Primitive cell-derived tumours were the most common in the first decade (24/45, 53.4%) and were the largest (82 [60-100] mm), whereas bronchial NETs predominated during the second decade (42/116, 36.2%) and were the smallest (15 [10-25] mm). Computed tomography localized 92.9% (118/127) of paediatric EAS patients. Immediate postoperative remission was attained in 77.9% (88/113) patients, whereas 30.4% (24/79) relapsed over a median (IQR) period of 13 (8-36) months. Over a median (IQR) follow-up of 2 (0.6-4.6) years, 31.4% of patients died. The median survival was higher in bronchial NET than in other tumour groups. Distant metastasis and tumour size were independent negative predictors of survival.

CONCLUSIONS

Aetiological profile of paediatric and adolescent EAS is distinct from that of adults. Bronchial NETs have the best long-term survival, whereas distant metastasis and tumour size predict poor survival.

Case Report: Severe McCune-Albright syndrome presenting with neonatal Cushing syndrome: navigating through clinical obstacles

Background

Café-au-lait skin macules, Cushing syndrome (CS), hyperthyroidism, and liver and cardiac dysfunction are presenting features of neonatal McCune-Albright syndrome (MAS), CS being the rarest endocrine feature. Although spontaneous resolution of hypercortisolism has been reported, outcome is usually unfavorable. While a unified approach to diagnosis, treatment, and follow-up is lacking, herein successful treatment and long-term follow-up of a rare case is presented.

Clinical case

An 11-day-old girl born small for gestational age presented with deterioration of well-being and weight loss. Large hyperpigmented macules on the trunk, hypertension, hyponatremia, hyperglycemia, and elevated liver enzymes were noted. ACTH-independent CS due to MAS was diagnosed. Although metyrapone (300 mg/m2/day) was started on the 25th day, complete remission could not be achieved despite increasing the dose up to 1,850 mg/m2/day. At 9 months, right total and left three-quarters adrenalectomy was performed. Cortisol decreased substantially, ACTH remained suppressed, rapid tapering of hydrocortisone to physiological dose was not tolerated, and supraphysiological doses were required for 2 months. GNAS analysis from the adrenal tissue showed a pathogenic heterozygous mutation. During 34 months of follow-up, in addition to CS due to MAS, fibrous dysplasia, hypophosphatemic rickets, and peripheral precocious puberty were detected. She is still regularly screened for other endocrinopathies.

Conclusion

Neonatal CS due to MAS is extremely rare. Although there is no specific guideline for diagnosis, treatment, or follow-up, addressing side effects and identifying treatment outcomes will improve quality of life and survival.

Paediatric Cushing's disease: Epidemiology, pathogenesis, clinical management and outcome

Cushing's disease (CD) is rare in paediatric practice but requires prompt investigation, diagnosis and therapy to prevent long-term complications. Key presenting features are a change in facial appearance, weight gain, growth failure, virilization, disturbed puberty and psychological disturbance. Close consultation with an adult endocrinology department is recommended regarding diagnosis and therapy. The incidence of CD, a form of ACTH-dependent Cushing's syndrome (CS), is equal to approximately 5% of that seen in adults. The majority of ACTH-secreting adenomas are monoclonal and sporadic, although recent studies of pituitary tumours have shown links to several deubiquitination gene defects. Diagnosis requires confirmation of hypercortisolism followed by demonstration of ACTH-dependence. Identification of the corticotroph adenoma by pituitary MRI and/or bilateral inferior petrosal sampling for ACTH may contribute to localisation before pituitary surgery. Transsphenoidal surgery (TSS) with selective microadenomectomy is first-line therapy, followed by external pituitary irradiation if surgery is not curative. Medical therapy to suppress adrenal steroid synthesis is effective in the short-term and bilateral adrenalectomy should be considered in cases unfit for TSS or radiotherapy or when urgent remission is needed after unsuccessful surgery. TSS induces remission of hypercortisolism and improvement of symptoms in 70-100% of cases, particularly when performed by a surgeon with experience in children. Post-TSS complications include pituitary hormone deficiencies, sub-optimal catch-up growth, and persisting excess of BMI. Recurrence of hypercortisolism following remission is recognised but infrequent, being less common than in adult CD patients. With experienced specialist medical and surgical care, the overall prognosis is good. Early referral to an experienced endocrine centre is advised.

An Optimized Pathway for the Differential Diagnosis of ACTH-Dependent Cushing's Syndrome Based on Low-Dose Dexamethasone Suppression Test

CONTEXT

Traditionally, low-dose dexamethasone suppression test (LDDST) was used to confirm the diagnosis of Cushing's syndrome (CS), and high-dose dexamethasone suppression test (HDDST) was used to differentiate Cushing's disease (CD) and ectopic adrenocorticotropin (ACTH) syndrome (EAS), but some studies suggested that HDDST might be replaced by LDDST. For the differential diagnosis of CS, dexamethasone suppression test was usually combined with other tests such as bilateral petrosal sinus sampling (BIPSS) and pituitary magnetic resonance imaging, but the optimal pathway to incorporate these tests is still controversial.

OBJECTIVES

To develop an optimized pathway for the differential diagnosis of CD and EAS based on LDDST.

DESIGN AND SETTING

Single-center retrospective study (2011-2019).

PATIENTS

Two hundred sixty-nine CD and 29 EAS patients with pathological diagnosis who underwent consecutive low- and high-dose DST.

RESULTS

For the differential diagnosis of CD and EAS, the area under curve (AUC) of LDDST using urine free cortisol (0.881) was higher than that using serum cortisol (0.685) (p < 0.001) in head-to-head comparison among a subgroup of 108 CD and 10 EAS. The AUC of LDDST (0.883) was higher than that of HDDST (0.834) among all the included patients. With the cutoff of <26%, the sensitivity and specificity of LDDST were 39.4% and 100%. We designed a new pathway in which BIPSS was only reserved for those patients with unsuppressed LDDST and adenoma <6mm, yielding an overall sensitivity of 97.7% and specificity of 86.7%.

CONCLUSION

LDDST had similar value to HDDST in differentiating CD and EAS using the specific cutoff point. The pathway that combined LDDST and BIPSS could differentiate CD and EAS accurately.

Bronchial Carcinoid Tumour as a Rare Cause of Cushing’s Syndrome in Children: A Case Report and Review of Literature

Cushing’s syndrome (CS) is rare in childhood and adolescence. The most common paediatric cause of CS is exogenous administration of glucocorticoids; either topical, inhaled or oral corticosteroids. Endogenous causes can be classified into adrenocorticotropic hormone (ACTH) independent and ACTH dependent causes. Herein, we report our experience of managing a 12 year old girl who presented with features of CS and was found to have an ectopic, ACTH-secreting bronchial carcinoid tumour, which was resected surgically. Our patient was managed successfully by multidisciplinary approach and has recovered from hypertension and Cushing’s habitus. The English language literature was searched from 2019 back, using PubMed, Google and Google Scholar. Keywords used for the search were; “Ectopic ACTH syndrome (EAS) in children”, “bronchial carcinoid in children” and “Cushing’s Syndrome in children”. Children with bronchial carcinoid tumours causing EAS were identified. Case variables such as age, sex, type of carcinoid, investigations, surgery, recurrences and outcome were reviewed. Fourteen cases of paediatric bronchial carcinoid producing ACTH were found with a mean age of 15.8 years and female preponderance. Most of the patients had a right lung lesion and histological appearance was typical of carcinoid tumour. Bronchial carcinoid is extremely rare in children and only 4% are associated with CS. The postoperative treatment of CS is challenging with a high prevalence of hypertension, increased body mass index and visceral fat mass, impaired cognitive function and decreased quality of life. A careful follow up is indispensable for monitoring recurrence of carcinoid and complete remission of CS.

Management of Cushing syndrome in children and adolescents: experience of a single tertiary centre

The diagnosis and management of paediatric Cushing syndrome (CS) is highly challenging. This study aims to characterise its presentation, diagnosis, management and outcome by a retrospective case review of 30 patients (14 females) followed at a single tertiary paediatric endocrinology centre over a 30-year period. At presentation, median age was 8.9 years (0.2-15.5) and the commonest manifestations were weight gain (23/30), hirsutism (17/30), acne (15/30) and hypertension (15/30). Growth retardation was present in 11/30. Median body mass index (BMI) was +2.1 standard deviation score (SDS) (-6.5 to +4.6). Urinary free cortisol (UFC) was abnormal in 17/18 (94 %), midnight cortisol in 27/27 (100 %) and low-dose dexamethasone suppression (LDDS) test in 20/20 (100 %). High-dose dexamethasone suppression (HDDS) test was abnormal in 6/6 (100 %) of adrenal tumours, 1/10 (10 %) of Cushing disease (CD) and 1/2 (50 %) of ectopic tumours. Bilateral inferior petrosal sinus sampling (IPSS) identified five CD cases and one ectopic tumour. All patients underwent surgery and subsequently required cortisol replacement. Final diagnoses were 16 CD, 11 adrenal disease, 2 ectopic ACTH-secreting lesions and 1 case of unidentified aetiology. One year post-diagnosis, median BMI was 0.5 SDS (-2.5 to +3.7), hypertension was present in 4/14 (28 %), and 43 % (12/30) of individuals were off hydrocortisone.

CONCLUSION

The prevalence of the clinical manifestations differs from that reported in other series. Screening tests were highly sensitive, with UFC, midnight cortisol and LDDS performing well. One year post-treatment, BMI and BP normalised in the majority of patients and almost half of them were able to discontinue replacement hydrocortisone.

WHAT IS KNOWN

•Cushing syndrome is an extremely rare entity in the paediatric and adolescent age groups, so not many cohort studies have been published in this population. •Several tests can be employed to firstly diagnose hypercortisolaemia and secondly identify the source of origin of it. The efficacy and safety of these tests in children is still uncertain. What is New: •This study includes cases due to the different aetiologies of endogenous hypercortisolaemia (pituitary, adrenal and ectopic hypercortisolaemia) allowing us to compare the differences in presentation, diagnosis, management and long-term outcome between the groups. •There is a difference in the prevalence of Cushing syndrome symptoms and in the performance of the tests in our cohort compared to previously published studies in the literature.

The hypertension of Cushing's syndrome: controversies in the pathophysiology and focus on cardiovascular complications

Cushing's syndrome is associated with increased mortality, mainly due to cardiovascular complications, which are sustained by the common development of systemic arterial hypertension and metabolic syndrome, which partially persist after the disease remission. Cardiovascular diseases and hypertension associated with endogenous hypercortisolism reveal underexplored peculiarities. The use of exogenous corticosteroids also impacts on hypertension and cardiovascular system, especially after prolonged treatment. The mechanisms involved in the development of hypertension differ, whether glucocorticoid excess is acute or chronic, and the source endogenous or exogenous, introducing inconsistencies among published studies. The pleiotropic effects of glucocorticoids and the overlap of the several regulatory mechanisms controlling blood pressure suggest that a rigorous comparison of in-vivo and in-vitro studies is necessary to draw reliable conclusions. This review, developed during the first ‘Altogether to Beat Cushing's syndrome’ workshop held in Capri in 2012, evaluates the most important peculiarities of hypertension associated with CS, with a particular focus on its pathophysiology. A critical appraisal of most significant animal and human studies is compared with a systematic review of the few available clinical trials. A special attention is dedicated to the description of the clinical features and cardiovascular damage secondary to glucocorticoid excess. On the basis of the consensus reached during the workshop, a pathophysiology-oriented therapeutic algorithm has been developed and it could serve as a first attempt to rationalize the treatment of hypertension in Cushing's syndrome.

Cushing disease in a toddler: not all obese children are just fat

Cushing disease is exceedingly rare in children, especially in those under the age of 2 years. This case report describes an 18-month-old female child who presented with morbid obesity, decreased linear growth, and reversal of developmental milestones. Her diagnosis was delayed; however, she was successfully treated by surgical excision of the microadenoma. This was followed by resolution of signs and symptoms of Cushing syndrome. Although the patient's hypertension resolved, linear growth improved and development began to progress, she is still developmentally delayed and now has hypopituitarism. Review of this case, as well as a handful of other cases of infantile Cushing disease in the literature, suggests that features such as hypertension and slowed linear growth, which are rare in nutritional causes of obesity in infants, can help identify this rare, but life-threatening, illness among an increasing number of overweight infants.

Dynamic testing in Cushing's syndrome

Endogenous Cushing's syndrome (CS) results from chronic exposure to excess glucocorticoids. CS can be ACTH-dependent, caused by ACTH-secreting pituitary or ectopic tumours, or ACTH-independent, caused by cortisol-secreting adrenal tumours. CS can be an extremely difficult diagnosis to make, and assessment will include clinical, biochemical and radiological evaluation. Several screening tests are used for the confirmation of hyper-cortisolaemia and its differentiation from other, more frequent, clinical abnormalities, such as simple obesity, hypertension, depression etc. Other dynamic tests are useful for establishing the aetiology. We have reviewed the current literature on the diagnosis of CS, and based on these data and our own experience, suggest the most useful tests and diagnostic criteria to be used. We conclude that even though laboratory testing is a fundamental part of the investigation of patients with CS, the interpretation of the tests should always be performed with extreme care, as none of the tests has proven fully capable of distinguishing all cases of CS. The biochemical results should be interpreted jointly with the clinical aspects and the radiology findings in a probabilistic matrix, and not as part of a uniform algorithm.

Paediatric Cushing's syndrome: epidemiology, investigation and therapeutic advances

Cushing's syndrome (CS), which is caused by excessive circulating glucocorticoid concentrations, is rare in the paediatric age range but presents a diagnostic and therapeutic challenge. Most paediatric endocrinologists have limited experience of managing children or adolescents with CS and thus benefit from close consultation with colleagues who treat adult patients. A protocol for investigation is required that broadly follows the model for adult patients. Here, the epidemiology and diagnosis of different causes of CS are discussed according to typical age of presentation. Treatment strategies for adrenocorticotrophic hormone (ACTH)-independent and ACTH-dependent CS are described and critically appraised. The management of paediatric CS patients after cure also presents challenges for optimizing growth, bone health, reproduction and body composition from childhood into and during adult life.