Hypokalemia Due to Ectopic Adrenocorticotropic Hormone.

Hypokalemia is a common disorder in clinical practice. The underlying pathophysiology can be attributed to 3 main mechanisms: insufficient potassium intake, excessive urinary or gastrointestinal losses, and transcellular shift. Renal loss is the most common cause of hypokalemia. Renal loss of potassium can occur due to diuretics, mineralocorticoid excess or hypercortisolism (Cushing syndrome). Among patients with Cushing syndrome, ectopic adrenocorticotropic hormone (ACTH) is the most frequent cause. We present a case of hypokalemia and hypertension due to ectopic ACTH production leading to Cushing syndrome.

Ectopic Hormonal Syndromes: Cushing's Syndrome and Acromegaly.

Ectopic hormone production may be present in neuroendocrine and non-endocrine neoplasms. Ectopic sources of growth hormone, adrenocorticotropin (ACTH), or their releasing factors are uncommon but clinically relevant. Ectopic ACTH tumors have been studied more than the rest, but there are still no comprehensive multidisciplinary guidelines that include all the pitfalls in the diagnosis and management of ectopic hormonal syndromes and the neoplasms associated with ectopic Cushing or acromegaly. The frequency of neuroendocrine neoplasms and other neoplasms with neuroendocrine differentiation has been increasing in recent decades. The review of the available data on these tumors, their classification, and improvements in diagnostic and therapeutic procedures is important to understand the relevance of ectopic Cushing's syndrome and acromegaly in clinical practice.

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.

[Infectious pneumonia favored by paraneoplastic Cushing syndrome in a pulmonary carcinoid tumor]. / Pneumopathie infectieuse favorisée par un syndrome de Cushing paranéoplasique d'une tumeur carcinoïde pulmonaire.

INTRODUCTION: Ectopic Cushing's syndrome (CS) is a rare condition nevertheless well-known to endocrinologists. The pneumologist may be called upon to treat CS not only because bronchial carcinoid tumors are the most frequent source of ectopic ACTH secretion, but also due to the fact that the immunosuppression induced by hypercorticism favors lower respiratory tract infections. CASE REPORT: We report the case of a female patient presenting with acute respiratory failure secondary to Enterobacter cloacae pneumonia exacerbated by SC. Further investigations confirmed ectopic ACTH secretion and revealed a right upper lobe pulmonary nodule. After appropriate antibiotic therapy, the patient received preoperative adrenolytic treatment. Management by right upper lobectomy resulted in the extraction of a 12mm tumor. Pathological analysis was consistent with the diagnosis of a typical carcinoid tumor. Immunohistochemistry confirmed ACTH secretion by the tumor. Even though the postoperative course showed CS regression, the patient developed adrenal insufficiency. CONCLUSION: Ectopic CS induces immunosuppression, which aggravates lower respiratory tract infections. Search for a pulmonary neuroendocrine tumor should be systematic. Following control of the secretory syndrome by adrenolytic treatment, and if the diagnosis of carcinoid tumor is confirmed, surgical treatment is the preferred option.

Expressions of Cushing's syndrome in multiple endocrine neoplasia type 1.

Cushing's syndrome (CS) resulting from endogenous hypercortisolism can be sporadic or can occur in the context of familial disease because of pituitary or extra-pituitary neuroendocrine tumors. Multiple endocrine neoplasia type 1 (MEN1) is unique among familial endocrine tumor syndromes because hypercortisolism in this context can result from pituitary, adrenal, or thymic neuroendocrine tumors and can therefore reflect either ACTH-dependent or ACTH-independent pathophysiologies. The prominent expressions of MEN1 include primary hyperparathyroidism, tumors of the anterior pituitary, gastroenteropancreatic neuroendocrine tumors, and bronchial carcinoid tumors along with several common non-endocrine manifestations such as cutaneous angiofibromas and leiomyomas. Pituitary tumors are present in about 40% of MEN1 patients, and up to 10% of such tumors secrete ACTH that can result in Cushing's disease. Adrenocortical neoplasms occur frequently in MEN1. Although such adrenal tumors are mostly clinically silent, this category can include benign or malignant tumors causing hypercortisolism and CS. Ectopic tumoral ACTH secretion has also been observed in MEN1, almost exclusively originating from thymic neuroendocrine tumors. The range of clinical presentations, etiologies, and diagnostic challenges of CS in MEN1 are reviewed herein with an emphasis on the medical literature since 1997, when the MEN1 gene was identified.

[Cyclic Cushing's syndrome: difficulties of diagnostic search and choice of treatment tactics. A clinical case].

Cyclic Cushing's syndrome is a pathological condition characterized by alternating periods of excessive cortisol secretion with corresponding clinical manifestations and periods of spontaneous remission of the disease.To diagnose Cyclic Cushing's syndrome it is necessary to record at least three episodes of excessive cortisol secretion alternating with periods of normalization of its production.In most cases, this pathology is diagnosed in patients with ACTH-secreting pituitary tumor, however, there are rare cases of cyclic hypercorticism with ectopic ACTH secretion by tumors of different localization and without verification of pathological hormonal secretion focus. In addition, cyclic hyperproduction of cortisol can be also observed in ACTH-independent Cushing's syndrome associated with the presence of corticosteroma or adrenal hyperplasia. The exact causes and mechanisms of the cyclic hypercorticism are currently insufficiently studied.Due to the atypical course of the disease, the unpredictability of the occurrence of a new «cycle¼, the variability of its duration and manifestations (not only in different patients, but also in the same patient), verification of the diagnosis and determination of treatment tactics may be difficult in the daily practice of specialists, and the prevalence of this condition can be undervalued.

An exceptionally rare case of Cushing's syndrome caused by ectopic ACTH syndrome due to olfactory neuroblastoma in childhood.

OBJECTIVES: Ectopic adrenocorticotropic hormone secretion/syndrome (EAS) is caused by excess secretion of ACTH leading to hypercortisolism by non-pituitary, commonly malignant origins. We present a rare case of esthesioneuroblastoma (ENB) complicated by EAS in the follow-up period. CASE PRESENTATION: A child presented with nasal obstruction at the age of 10 months. Polypoid mass obstructing the right nasal passage was detected. Magnetic resonance imaging (MRI) showed a lesion limited within the nasal cavity. The lesion was completely removed by nasal endoscopic surgery. The pathologic examination revealed a diagnosis of esthesioneuroblastoma. It was confined to the nasal cavity so chemotherapy/radiotherapy was not administered and began to follow up. At 28 months of age, he presented with rapid weight gain. Laboratory data were consistent with Cushing's syndrome (CS). High-dose dexamethasone suppression test and imaging studies led us to think of ectopic ACTH syndrome originated from ENB relapse. After partial resection of the tumor, ketoconazole treatment was started along with chemotherapy. Hypercortisolemia was kept under control with ketoconazole treatment as long as the treatment was maintained. CONCLUSIONS: Cushing syndrome is a rare endocrine disorder. Adrenal sources of hypercortisolism and ectopic sources of ACTH overproduction should be investigated especially in young children.

ACTH-secreting metastatic prostate cancer with neuroendocrine differentiation.

Cushing's syndrome (CS) due to ectopic adrenocorticotropic hormone (ACTH) secretion (EAS) can result from a variety of tumours and rarely from those of prostatic origin. We present a male patient in his early 60s with ACTH-secreting metastatic prostate adenocarcinoma with neuroendocrine differentiation (ICD-O code 8574/3) years after prostatectomy and androgen-deprivation therapy, initially presenting with Cushingoid features. After open radical prostatectomy and bilateral orchiectomy for disease recurrence, the patient was found to have metastatic liver and bone lesions highly suggestive of metastatic prostatic cancer. About 10% of cells on liver biopsy expressed ACTH, a finding consistent with EAS as the cause of CS. His stay was complicated with multiple infections and ultimate death. Hence, we report a case of metastatic prostate adenocarcinoma with neuroendocrine differentiation who presented with CS. We also emphasize the importance of adequate and timely treatment.

Medullary Thyroid Cancer with Ectopic Cushing's Syndrome: A Case Report and Systematic Review of Detailed Cases from the Literature.

Background: Medullary thyroid cancer (MTC) is a neuroendocrine tumor arising from parafollicular C-cells of the thyroid gland that, in rare cases, can cause a paraneoplastic ectopic Cushing's syndrome (ECS). The development of Cushing's syndrome (CS) in MTC patients is generally associated with advanced disease and poor prognosis. Summary: We described a case of severe CS due to MTC in a young male. We performed a systematic review to identify cases of ECS due to MTC. We searched PubMed, Scopus, and Web of Science for publications between database inception and February 2022 and we collected the patient characteristics, disease presentation, employed treatment strategies, and disease outcomes. In addition to our patient, we identified 96 cases of ECS due to MTC reported in literature. Mean age at diagnosis was 44.4 years (range 10-84), and there was a male predominance (male:female [M:F] = 1.8:1). Most patients (51%) presented with metastatic disease at diagnosis and showed severe hypercortisolism. Seventeen patients developed distant metastasis and hypercortisolism during follow-up. Interestingly, in 48% of patients, the diagnosis of CS followed the diagnosis of MTC with a median time of 48 months but, among patients in whom the diagnosis was concomitant (38%), symptoms due to hypercortisolism were frequently the reason for seeking medical advice. Pathology results showed evidence of adrenocorticotropic hormone (ACTH) or corticotropin releasing hormone (CRH) positive cells in 76% of patients in whom they were tested. The management of hypercortisolism was challenging in most patients with 48% requiring, eventually, definitive treatment with bilateral adrenalectomy (BLA). Recently, some limited evidence has emerged regarding tyrosine kinase inhibitors (TKIs) treatment for hypercortisolism in patients with ECS due to MTC. Despite limited information on survival, prognosis was generally poor and the main causes of death were either complications of CS or disease progression. Conclusions: Despite its rarity, MTC should be considered in the differential diagnosis of ECS. Management of hypercortisolism is a key factor to improve the patient's symptoms but it is often challenging and BLA is frequently required. Further studies are needed for investigating the role of TKIs in patients with MTC with ECS.

Somatostatin Receptor-negative and Fluorodeoxyglucose-positron Emission Tomography-positive Lung Neuroendocrine Tumor G1 Exhibiting Cyclic Cushing's Syndrome.

Localization of ectopic cyclic Cushing's syndrome, which causes life-threatening complications, is challenging. A 70-year-old woman showed cyclic hypokalemia and hyperglycemia and was diagnosed with cyclic ectopic Cushing's syndrome. Although somatostatin-receptor scintigraphy failed to localize the responsible tumor, fluorodeoxyglucose-positron emission tomography (FDG-PET) showed the uptake of tracer in a lung tumor. Lobectomy resulted in remission. The resected adrenocorticotropic hormone (ACTH)-producing neuroendocrine tumor had Ki-67<2% and negative staining for somatostatin receptors. This is the first case assessed both radiological findings and pathological findings in cyclic ectopic Cushing's syndrome. Subsequent FDG-PET is recommended if somatostatin-receptor scintigraphy is negative.

Successful resolution of ectopic Cushing syndrome by minimally invasive thoracoscopic resection of the neuroendocrine tumor of the thymus: a rare case report.

BACKGROUND: Ectopic Cushing syndrome (ECS) is a sporadic condition. Even uncommon is an ECS that derives from a carcinoid tumor of the thymus. These tumors may pose several diagnostic and therapeutic conundrums. This report discusses the differential diagnosis, clinicopathological findings, and effective treatment of a rare case of ECS using a minimally invasive approach. CASE PRESENTATION: A 29-year-old woman with Cushing syndrome presented with facial flushing. Physical examination revealed hypertension (blood pressure: 141/100 mmHg). A mediastinal tumor was discovered to be the cause of the patient's chronic hypokalemia and hypercortisolemia. Cortisol levels increased in the morning, reaching 47.7 ug/dL. The levels of the hormones ACTH, aldosterone, and renin were determined to be 281 pg/mL, 3.0 ng/dL, and 2.1 pg/mL, respectively. The presence of hypertension, hypokalemia, and alkalinity suggested Cushing's syndrome, which was proven to be ACTH-dependent ECS by a dexamethasone suppression test. A chest CT scan revealed inflammation in the posterior basal region of the right lower lobe. The superior anterior mediastinum was characterized by round-shaped isodensity lesions with distinct borders. She underwent thoracoscopic anterior mediastinal tumor excision via the subxiphoid technique (R0 resection); following surgery, her blood pressure returned to normal, and the hypernatremia/hypopotassemia resolved. The tumor was determined to be a thymic carcinoid. Most notably, cortisol levels fell to half of their presurgical levels after one hour of surgery, and other abnormalities corrected substantially postoperatively. CONCLUSION: Thoracoscopic excision of thymic tumors by subxiphoid incision may be a useful treatment option for ECS caused by neuroendocrine tumors of the thymus.

Management of adrenocorticotropic hormone-secreting neuroendocrine tumors and the role of bilateral adrenalectomy in ectopic Cushing syndrome.

BACKGROUND: Neuroendocrine tumors can cause ectopic Cushing syndrome, and most patients have metastatic disease at diagnosis. We identified risk factors for outcome, evaluated ectopic Cushing syndrome management, and explored the role of bilateral adrenalectomy in this population. METHODS: This was a retrospective study including patients with diagnosis of ectopic Cushing Syndrome secondary to neuroendocrine tumors with adrenocorticotropic hormone secretion treated at our quaternary referral center over a 40-year period (1980-2020). RESULTS: Seventy-six patients were included. Mean age at diagnosis was 46.3 ± 15.8 years. Most patients (N = 61, 80%) had metastases at ectopic Cushing syndrome diagnosis. Average follow-up was 2.9 ± 3.7 years (range, 4 months-17.2 years). Patients with neuroendocrine tumors before ectopic Cushing syndrome had more frequent metastatic disease and resistant ectopic Cushing syndrome. Patients with de novo hyperglycemia, poor neuroendocrine tumor differentiation, and metastatic disease had worse survival. Of those with nonmetastatic disease, 8 (53%) had ectopic Cushing syndrome resolution after neuroendocrine tumor resection, 3 (20%) were medically controlled, and 4 (27%) underwent bilateral adrenalectomy. In patients with metastatic neuroendocrine tumors, hypercortisolism was initially medically managed in 92%, 3% underwent immediate bilateral adrenalectomy, 2% had control after primary neuroendocrine tumor debulking, and 2% were lost to follow-up. Medical treatment resulted in hormonal control in 7 (13%) patients. Of the 49 patients with metastatic disease and medically resistant ectopic Cushing syndrome, 23 ultimately had bilateral adrenalectomy with ectopic Cushing syndrome cure in all. CONCLUSION: Patients with neuroendocrine tumors before ectopic Cushing syndrome development were more likely metastatic and had worse survival. De novo hyperglycemia and poor neuroendocrine tumor differentiation were predictive of worse prognosis. Medical control of hypercortisolism is difficult to achieve in patients with neuroendocrine tumors-ectopic Cushing syndrome. Well-selected patients may benefit from bilateral adrenalectomy early in the treatment algorithm, and multidisciplinary management is essential in this complex disease.

Arterial hypertension of infrequent cause

Arterial hypertension is generally classified as primary or essential (90%), and secondary (10%). Infrequent causes of the latter include Cushing's syndrome, classified as ACTH-dependent and independent. A small percentage of ACTH-independent cases are due to ectopic ACTH secretion, generally due to neoplasia, and can present as arterial hypertension and hyperglycaemia that are refractory to pharmacological measures, metabolic alkalosis and hypokalaemia that are difficult to control, but which help guide the initial diagnosis. We present two clinical cases with a diagnosis of ectopic ACTH secretion secondary to small cell lung carcinoma, in which one of the debut manifestations was unknown, difficult to control arterial hypertension.(AU)

La hipertensión arterial generalmente se clasifica en primaria o esencial (90%) y secundaria (10%). Entre las causas infrecuentes de esta última se encuentra el síndrome de Cushing, el cual se clasifica en hormona adrenocorticotropa (ACTH) dependiente e independiente. Un pequeño porcentaje de los casos de ACTH independiente son debidos a la secreción ectópica de ACTH, generalmente por neoplasias, pudiendo tener como manifestaciones, hipertensión arterial e hiperglucemia refractarias a medidas farmacológicas, alcalosis metabólica e hipopotasemia de difícil control, que por otra parte, sirven como orientación diagnóstica inicial. Presentamos dos casos clínicos con diagnóstico de secreción ectópica de ACTH secundaria a carcinoma microcítico de pulmón, en los que una de las manifestaciones principales al debut fue una hipertensión arterial no conocida de difícil control.(AU)

Appendiceal Neuroendocrine Tumor Is a Rare Cause of Ectopic Adrenocorticotropic Hormone Syndrome With Cyclic Hypercortisolism: A Case Report and Literature Review.

OBJECTIVE: Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is a condition of hypercortisolism caused by non-pituitary tumors secreting ACTH. Appendiceal neuroendocrine tumor as a rare cause of ectopic ACTH syndrome was reported scarcely. We aimed to report a patient diagnosed with EAS caused by an appendiceal neuroendocrine tumor and summarized characteristics of these similar cases reported before. CASE REPORT AND LITERATURE REVIEW: We reported a case with Cushing's syndrome who was misdiagnosed as pituitary ACTH adenoma at first and accepted sella exploration. Serum and urinary cortisol decreased, and symptoms were relieved in the following 4 months after surgery but recurred 6 months after surgery. The abnormal rhythm of plasma cortisol and ACTH presented periodic secretion and seemingly rose significantly after food intake. EAS was diagnosed according to inferior petrosal sinus sampling (IPSS). Appendiceal mass was identified by 68Ga-DOTA-Tyr3-octreotate (DOTATATE)-PET-CT and removed. The pathological result was consistent with appendiceal neuroendocrine tumor with ACTH (+). The literature review demonstrated 7 cases diagnosed with EAS caused by appendiceal neuroendocrine tumor with similarities and differences. CONCLUSION: The diagnosis of an ectopic ACTH-producing tumor caused by the appendiceal neuroendocrine tumor can be a challenging procedure. Periodic ACTH and cortisol secretion may lead to missed diagnosis and misdiagnosis. IPSS is crucial in the diagnosis of EAS and 68Ga-DOTATATE-PET-CT plays an important role in the identification of lesions.

Cushing's syndrome due to ectopic adrenocorticotropin secretion by a parotid carcinoma

SUMMARY We report a rare case of Cushing's syndrome in a 37-year-old female who initially presented with localized acinic cell carcinoma of the parotid gland. In January 2014, she underwent a right parotidectomy with facial nerve preservation and adjuvant radiotherapy. In August 2018, she presented a histologically-proven local regional relapse. The patient was considered for salvage surgery with facial nerve sacrifice and remained with no evidence of disease. One year later the patient developed pulmonary dissemination and started to gain weight and developed facial plethora and acne on the face and upper trunk. In a physical examination, the patient presented moon face, buffalo hump, acne and stage 2 hypertension. Biochemical evaluation confirmed ACTH-dependent Cushing's syndrome. IHC for ACTH in the lung biopsy revealed strong positive staining for ACTH confirming a diagnosis of ectopic ACTH secretion by a metastatic parotid acinic cell carcinoma. Ketoconazole (600 mg/d) was started to treat the CS. In addition, as chemotherapy was initiated to treat the metastatic disease. After the fifth cycle of chemotherapy, ketoconazole was suspended and the patient remained in remission of CS for four months, when CS recurred. A unique feature of this case is related to the clinical CS relapse associated with disease progression, which needed prompt treatment with ketoconazole, resulting in a significant improvement in the patient's condition. Although rare, should be attentive for possible CS features in patients with high-grade salivary gland carcinomas, since the diagnosis of ectopic secretion of ACTH may significantly impact their management and outcomes.

A rare case of pancreatic neuroendocrine neoplasm causing Cushing's syndrome.

Pancreatic neuroendocrine neoplasms (PNENs) are relatively rare with a reported incidence of 1-2/100,000 and generally thought to originate from the precursor of the neuroendocrine cells including the islet and the pancreatic duct cells. About 65% of PNENs are non-functional. While insulinomas and gastrinomas are the most common functional PNENs, ACTH-producing PNENs are extremely rare. We herein present an extremely rare case of a patient with Cushing's syndrome caused by PNEN. A 46-year-old woman with edema in bilateral lower extremities and moon face was admitted with a suspicious pancreatic tumor. Enhanced computed tomography and endoscopic ultrasonography revealed a pancreatic tumor. The final diagnosis of ACTH-producing PNEN with Cushing's syndrome was based on clinical and biochemical test results and endocrinological studies. The symptoms associated Cushing's syndrome improved after pancreaticoduodenectomy for PNEN.

Cushing's syndrome due to ectopic adrenocorticotropin secretion by a parotid carcinoma.

We report a rare case of Cushing's syndrome in a 37-year-old female who initially presented with localized acinic cell carcinoma of the parotid gland. In January 2014, she underwent a right parotidectomy with facial nerve preservation and adjuvant radiotherapy. In August 2018, she presented a histologically-proven local regional relapse. The patient was considered for salvage surgery with facial nerve sacrifice and remained with no evidence of disease. One year later the patient developed pulmonary dissemination and started to gain weight and developed facial plethora and acne on the face and upper trunk. In a physical examination, the patient presented moon face, buffalo hump, acne and stage 2 hypertension. Biochemical evaluation confirmed ACTH-dependent Cushing's syndrome. IHC for ACTH in the lung biopsy revealed strong positive staining for ACTH confirming a diagnosis of ectopic ACTH secretion by a metastatic parotid acinic cell carcinoma. Ketoconazole (600 mg/d) was started to treat the CS. In addition, as chemotherapy was initiated to treat the metastatic disease. After the fifth cycle of chemotherapy, ketoconazole was suspended and the patient remained in remission of CS for four months, when CS recurred. A unique feature of this case is related to the clinical CS relapse associated with disease progression, which needed prompt treatment with ketoconazole, resulting in a significant improvement in the patient's condition. Although rare, should be attentive for possible CS features in patients with high-grade salivary gland carcinomas, since the diagnosis of ectopic secretion of ACTH may significantly impact their management and outcomes.

High-dose dexamethasone suppression test is inferior to pituitary dynamic enhanced MRI in the differential diagnosis of ACTH-dependent Cushing's syndrome.

PURPOSE: The differential diagnosis of adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome remains a challenge in clinical practice. The present study was aimed at assessing the diagnostic performance of pituitary dynamic contrast-enhanced magnetic resonance imaging (dMRI), high-dose dexamethasone suppression test (HDDST), and a combination of both tests for patients with ACTH-dependent Cushing's syndrome. METHODS: A total of 119 consecutive patients with ACTH-dependent Cushing's syndrome confirmed surgically were enrolled: 101 with proven Cushing's disease and 18 with proven ectopic ACTH syndrome. All patients underwent pituitary dMRI and HDDST. The sensitivity and specificity of pituitary dMRI, HDDST, and a combination of both tests were determined. RESULTS: The sensitivity and specificity of pituitary dMRI for diagnosing Cushing's disease were 80.2 and 83.3%, respectively, with a positive predictive value of 96.4%. The sensitivity and specificity of HDDST were 70.3 and 77.8%, respectively, with positive predictive value of 94.7%. A combination of both tests showed that the combined criteria of more than 50% suppression of serum cortisol on HDDST and a positive pituitary dMRI finding yielded a high specificity of 94.4 and sensitivity of 59.4%. The combined criteria of more than 68% suppression on HDDST and/or a positive pituitary dMRI finding yielded a sensitivity of 86.1% and specificity of 83.3%. CONCLUSIONS: Pituitary dMRI was superior to HDDST in the differential diagnosis of ACTH-dependent Cushing's syndrome. HDDST is recommended in combination with pituitary dMRI to establish a diagnosis process because of the significantly increased specificity with the combination.

Ectopic ACTH syndrome caused by thymic neuroendocrine tumor: a case report and literature review.

A 36-year-old woman presented with onset of reduced menstrual flow, gradually progressed to typical Cushingoid features with 24-hour urine free cortisol (UFC) increased, low-dose dexamethasone suppression test and high-dose dexamethasone suppression test both not suppressed, adrenocorticotropic hormone (ACTH) increased, and computed tomography (CT) scan of the chest revealed a large mass in the anterior mediastinum. The local hospital administered mediastinal mass resection which afterwards showed type B1 thymoma. The above symptoms were relieved post-operation, and the levels of ACTH and cortisol decreased. Symptoms recurred 5 months after the surgery, with laboratory and imaging suggested possible multiple tumor metastases. The patient was referred to our hospital and was diagnosed with ectopic ACTH syndrome and thymic neuroendocrine tumor with multiple metastases post-operation. After administered mifepristone to antagonize the glucocorticoid receptor, the patient's symptoms improved. The patient also received "etoposide" single-agent chemotherapy, and the symptoms were relieved after 4 months of follow-up. The case showed that complete surgical resection of the primary tumor is the best treatment for ectopic ACTH syndrome, if the primary tumor which cause ectopic ACTH syndrome cannot be completely cured, it is particularly important to control hypercortisolemia and prevent its complications. This article purports to report this case and review the relevant literature.