Ectopic ACTH syndrome of different origin-Diagnostic approach and clinical outcome. Experience of one Clinical Centre

Purpose

Ectopic Cushing Syndrome (EAS) is a rare condition responsible for about 5–20% of all Cushing syndrome cases. It increases the mortality of affected patients thus finding and removal of the ACTH-producing source allows for curing or reduction of symptoms and serum cortisol levels. The aim of this study is to present a 20-year experience in the diagnosis and clinical course of patients with EAS in a single Clinical Centre in Southern Poland as well as a comparison of clinical course and outcomes depending on the source of ectopic ACTH production–especially neuroendocrine tumors with other neoplasms.

Methods

Twenty-four patients were involved in the clinical study with EAS diagnosed at the Department of Endocrinology between years 2000 and 2018. The diagnosis of EAS was based on the clinical presentation, hypercortisolemia with high ACTH levels, high dose dexamethasone suppression test and/or corticotropin-releasing hormone tests. To find the source of ACTH various imaging studies were performed.

Results

Half of the patients were diagnosed with neuroendocrine tumors, whereby muscle weakness was the leading symptom. Typical cushingoid appearance was seen in merely a few patients, and weight loss was more common than weight gain. Patients with neuroendocrine tumors had significantly higher midnight cortisol levels than the rest of the group. Among patients with infections, we observed a significantly higher concentrations of cortisol 2400 levels in gastroenteropancreatic neuroendocrine tumors. Chromogranin A correlated significantly with potassium in patients with neuroendocrine tumors and there was a significant correlation between ACTH level and severity of hypokalemia.

Conclusion

EAS is not common, but if it occurs it increases the mortality of patients; therefore, it should be taken into consideration in the case of coexistence of severe hypokalemia with hypertension and muscle weakness, especially when weight loss occurs. Because the diagnosis of gastroenteropancreatic neuroendocrine tumor worsens the prognosis-special attention should be paid to these patients.

Cushing's syndrome secondary to ectopic ACTH secretion from carcinoid tumor within an ovarian mature teratoma: a case report and review of the literature

A 46-year-old woman with Cushing's syndrome secondary to ectopic adrenocorticotropic hormone (ACTH) secretion caused by primary ovarian mature teratoma with carcinoid components was presented in our case. The patient manifested sustained hypercortisolemia without circadian rhythm and a lack of suppression of either low-dose dexamethasone suppression test (LDDST) or high-dose dexamethasone suppression test (HDDST). There was no evidence of a pituitary mass or secretion of other hormones. After careful clinical evaluation, no other tumor masses were found. Resection of the ovarian tumors led to sharp reduction of serum ACTH and cortisol concentrations. Immunohistochemistry showed positivity in CgA, Syn, CK, NSE. To the best of our knowledge, there are rare reports of an ACTH-secreting carcinoid components located in an ovarian mature teratoma, and bilateral ovarian mature teratoma makes it rarer.

[Bronchopulmonary ACTH-producing tumors]

Neuroendocrine tumors have the ability to produce the hormones and vasoactive peptides. Excess of these hormones leads to different symptoms and syndromes because of organs' injuries. Detection of ACTH origin by using of modern diagnostic methods is not always possible. Lungs and bronchi are one of the most frequent localization of ACTH-producing tumors. It is considered that carcinoids with bronchopulmonary localization like a benign tumors in the clinical course. But at the same time carcinoid tends to metastasize, so timely diagnostics and treatment improve quality of life significant and increase the life expectancy of patients. The modern state of diagnostics and surgical treatment problem of ACTH-producing tumors with bronchopulmonary localization is presented in the article. It was described the brief historical background, clinical symptoms, instrumental and biochemical methods of diagnosis. The principles of surgical treatment are presented in the article.

Neuroendocrine carcinoma of the thyroid causing adrenocorticotrophic hormone-dependent Cushing's syndrome

BACKGROUND

Cushing's syndrome (CS) due to ectopic adrenocorticotrophic hormone (ACTH) and/or ectopic corticotropic releasing hormone (CRH) secretion accounts for <10% of all CS. Neuroendocrine carcinomas rarely cause CS. These carcinomas have been found to secrete either ACTH or rarely CRH. Herein we report a case of neuroendocrine carcinoma originating from the thyroid as the source of ACTH-dependent CS.

SUMMARY

A 30-year-old woman with features of CS presented with severe respiratory distress. Six months before that, she was diagnosed with primary hypothyroidism and started on levothyroxine (LT4) therapy. Biochemical evaluation was done, and nonsuppressed serum cortisol levels following dexamethasone with high ACTH confirmed a diagnosis of ACTH-dependent CS. Magnetic resonance imaging of the brain showed a bulky pituitary gland. Adrenal imaging showed bilateral adrenal hyperplasia. A computerized tomography scan showed a large anterior mediastinal mass arising from the neck and extending behind the transverse aortic arch. She underwent emergency thoracotomy due to rapidly progressive superior mediastinal syndrome and left vocal cord palsy. At surgery, the mass was seen originating from the thyroid and the thymus was compressed posteriorly. Near total thyroidectomy and thymectomy with removal of pericardial seedlings were done. Histopathology revealed sheets, cords, and nests of round or oval tumor cells with hyperchromatic nuclei and scant cytoplasm with local invasion and lymphovascular embolization suggestive of a neuroendocrine carcinoma arising from thyroid, staining positive for cytokeratin, synaptophysin, and chromogranin-A, and negative for calcitonin and carcinoembryonic antigen.

CONCLUSIONS

Here we report a case of a neuroendocrine tumor of the thyroid causing ACTH-dependent CS. The tumor was negative for calcitonin staining, indicating that this was not a medullary carcinoma of the thyroid. Neuroendocrine carcinomas originating from the thyroid gland are very rare. A thyroid tumor of neuroendocrine origin causing ACTH-dependent CS has not been reported previously.

Ectopic Cushing's syndrome: experience from a tertiary care centre

BACKGROUND & OBJECTIVE

Ectopic secretion of adrenocorticotropic hormone (ACTH) is rare, contributing to 10 per cent cases of endogenous Cushing's syndrome. We describe our experience of about two decades of patients with ectopic Cushing's syndrome (ECS) seen at a tertiary care centre from north India.

METHODS

Records of patients with ECS from 1985 to 2006 were retrospectively reviewed that included the presenting manifestations, clinical symptoms and signs, biochemical investigations including plasma cortisol, ACTH and high dose dexamethasone suppression test (HDDST), imaging modalities to localize the non pituitary source of ACTH production, management and follow up of these patients.

RESULTS

The study group included 12 patients (7 men) with mean (+/-SD) age at presentation 27.6 +/- 9.5 yr (range 13 to 48 yr) and the mean lag period between onset of symptoms and the diagnosis was 18.3 +/- 12.9 months with a range of 3 to 48 months. The weight loss (41.7%) followed by hyperpigmentation (25%) and infections (16.7%) were the common presenting manifestations. Cuticular atrophy (100%), hypertension (100%), bruise (92%) and proximal myopathy (83%) were the commonest signs. Plasma cortisol at 0800 h was 1267.3 +/- 483.3 nmol/l and at 2200 h was 1214.9 +/- 442.6 nmol/l indicating loss of circadian rhythm. The mean plasma ACTH was 221.1 +/- 55.9 (range 21.7 to 950 pg/ml). All but 2 patients had non-suppressibility of 0800 h plasma cortisol with HDDST. Five patients had thymic carcinoid, 3 had bronchial and one each had islet, hepatic and gut carcinoid and one had medullary thyroid carcinoma as a cause of ectopic ACTH secretion. The mean duration of follow up of these patients was 42.6 months and only two could sustain cure while remaining had either residual or recurrence.

INTERPRETATION & CONCLUSION

Ectopic Cushing's syndrome is a rare disease with varied manifestations and associated with increased morbidity and mortality. It presents with clinical features quite similar to classical Cushing's. Surgery with removal of primary tumour was found to be treatment of choice.

Evaluation of proopiomelanocortin mRNA in the peripheral blood from patients with Cushing's syndrome of different origin

ACTH-dependent Cushing's syndrome is due to ACTH overproduction originating from a pituitary corticotroph adenoma (Cushing's disease) or from ectopic tumors (ectopic ACTH syndrome). Due to difficulties in the differential diagnosis between these two forms of hypercortisolism it would be important to have molecular tools able to discriminate the two conditions. It is known that proopiomelanocortin (POMC) gene transcription can originate messengers of different length. ACTHomas show the normal 1072 nucleotides (nt) transcript, whereas ectopic tumors seem to be associated with a longer mRNA form (1450 nt). In order to analyse the presence of different POMC transcripts, we extracted total RNA from peripheral lymphocytes of 10 patients with Cushing's disease, 10 with ectopic Cushing syndrome, and 20 controls as well as from pituitary tissues (2 ACTH-omas and a normal pituitary polyA+ sample). Northern blot analysis correctly revealed a 1072 nt mRNA molecule in pituitary ACTH-oma and in the normal pituitary polyA+ RNA samples, whereas neither this molecule nor other alternative transcripts were detected in blood samples from patients and controls. These data were confirmed by the more sensitive RT-PCR technique. This study further underlines the need for alternative approaches in the diagnosis of ACTH-dependent Cushing's syndrome.

[Ectopic ACTH syndrome]

Although the clinical and biochemical discrimination of true Cushing syndrome from the Cushing phenotype is sometime difficult, four diagnostic studies are currently used: late-night serum and salivary cortisol level, urine free cortisol level, low-dose dexamethasone suppression, and the dexamethasone-CRH test. Using these tests, 90% of patients with Cushing syndrome are diagnosed. Once the diagnosis of the Cushing syndrome is firmly established, the next step is differential diagnosis of the subtype. Furthermore, the differentiation of pituitary and ectopic ACTH-dependent Cushing syndrome should be carried out using measurement of ACTH. Finally, bilateral petrosal sinus sampling for ACTH with CRH administration might be a powerful tool for a diagnosis for ectopic ACTH syndrome. A variety of benign and malignant tumors of non-pituitary tissues have been associated with the ectopic ACTH syndrome. The tumors most commonly associated with ACTH syndrome arise from neuroendocrine tissues, however, the pathogenesis of the ectopic ACTH syndrome remains unknown.

Assessment of GH reserve before and after successful treatment of adult patients with Cushing's syndrome

OBJECTIVE

Several studies have demonstrated impaired GH secretion in patients with active Cushing's syndrome (CS). It has been suggested that persistence of GH deficiency, despite treatment of cortisol excess, may delay the recovery of these patients and therefore temporary treatment with GH may have some benefit. However, the time course of restoration of GH secretion after successful treatment of CS has only been investigated in a limited number of mostly paediatric reports. The aim of the present study was the evaluation of GH reserve in adult patients with CS before and after correction of cortisol excess.

DESIGN AND PATIENTS

Sixteen patients (12 females, four males) with CS aged 44.7 +/- 5.05 years were recruited. These included seven patients with Cushing's disease, four patients with ectopic ACTH secretion and five patients with adrenal adenoma. All patients were evaluated before any therapeutic intervention. Twelve patients were successfully treated following appropriate surgery and these were further studied. The combined pyridostigmine/GHRH test was used to assess GH reserve in these patients. In a proportion of cases an insulin tolerance test (ITT) was also used.

RESULTS

Before any therapeutic intervention, an impaired GH response to PD/GHRH was noted in all patients. Restoration of GH response at 6 months was observed in six patients (50%); at 12 months in two; at 18 months in one patient. Two of the patients with no restoration of GH response at 12 months did not accept further investigation. Only one patient did not achieve an adequate GH response even when tested 30 months following cure of CS. Restoration of GH reserve was more commonly observed in those patients in whom there was recovery of the HPA axis. There was a good correlation between peak GH levels to PD + GHRH and ITT. No statistically significant difference was revealed in IGF-I levels between pre- and post-treatment evaluation.

CONCLUSIONS

Adult patients with active Cushing's syndrome demonstrate a profound suppression of stimulated GH secretion. In the majority of these patients the disruption of GH secretion is normalized within a year after successful treatment of endogenous cortisol excess.

Cushing's syndrome associated with adenocarcinoma of the lung

Paraneoplastic Cushing's syndrome caused by ectopic adrenocorticotropin production has been reported in association with a variety of malignant tumors. However, most cases of this syndrome are associated with neuroendocrine tumors such as small-cell lung cancer (SCLC), carcinoid tumors, and medullary carcinoma of the thyroid. We present a 49-year-old man who developed Cushing's syndrome associated with adenocarcinoma of the lung. He had a wide variety of clinical symptoms and comorbidity related to this syndrome during the course, and died 4 months after the diagnosis. This is a very rare case report of Cushing's syndrome associated with adenocarcinoma of the lung.

Pathophysiology of modulation of local glucocorticoid levels by 11beta-hydroxysteroid dehydrogenases

11beta-Hydroxysteroid dehydrogenases (11beta HSDs) are enzymes that catalyse the interconversion of active glucocorticoids (cortisol and corticosterone) into their inactive 11-keto products (cortisone and 11-deoxycorticosterone). Two isozymes have been identified: 11beta HSD type 1 is a predominant reductase, reactivating glucocorticoids from inert metabolites, whereas 11beta HSD type 2 is a potent dehydrogenase, inactivating glucocorticoids. They play a major role in the modulation of local cortisol levels and hence access of active steroid to corticosteroid receptors. This review focuses on the clinical importance of 11beta HSDs. We describe recent research that has not only advanced our understanding of the physiological role of these enzymes, but also their role in common diseases, including primary obesity and essential hypertension. These data provide encouragement that novel therapies will arise from a fuller understanding of the 11beta HSD system.

Ectopic adrenocorticotropin syndrome exhibiting paradoxical adrenocorticotropin responsiveness to gonadotropin-releasing hormone

In a 37-year-old man who had Cushing's syndrome, investigations, including overnight dexamethasone suppression test, corticotropin-releasing hormone (CRH) test, pituitary MRI and inferior petrosal sinus sampling suggested the presence of ectopic adrenocorticotropin (ACTH) production. Interestingly, gonadotropin-releasing hormone (GnRH) increased plasma ACTH from 73 pg/ml to 708 pg/ml at 15 min. Furthermore, desmopressin also increased plasma ACTH whereas CRH and thyrotropin-releasing hormone (TRH) had no effect. Such paradoxical responses of plasma ACTH were observed repeatedly. A thoracic CT scan revealed a right anterior mediastinal mass, which was surgically resected. Histological and immunohistochemical examination confirmed that the tumor was an ACTH-producing carcinoid. ACTH and cortisol decreased immediately following surgery. Neither desmopressin nor GnRH administration resulted in elevation of plasma ACTH while ACTH-responsiveness to dexamethasone and CRH was restored. To our knowledge, this is the first report documenting GnRH responsiveness in ectopic ACTH syndrome.

Ectopic ACTH production by a bronchial carcinoid tumour responsive to desmopressin in vivo and in vitro

A desmopressin-induced ACTH increase has been recently suggested to be specific for pituitary-dependent Cushing's disease. We present the case of a 47-year-old woman with Cushing's syndrome due to ectopic ACTH production by a bronchial carcinoid. While CRH failed to induce an ACTH or cortisol response, intravenous administration of desmopressin led to a 47% increase in serum ACTH and a 42% increase in serum cortisol concentration. After surgical removal of the tumour, the desmopressin response became negative. In vitro, ACTH production by tumour cells obtained at surgery was also stimulated by desmopressin but not by CRH. Additional receptor mRNA expression studies using RT-PCR revealed expression of both V2 and V3 vasopressin receptor subtypes in the carcinoid tumour at a level comparable to that recently described in pituitary corticotroph adenomas. This case illustrates that ACTH stimulation by desmopressin is not specific for pituitary-dependent Cushing's syndrome as vasopressin receptor subtypes known to interact with desmopressin may also be found in ectopic tumours producing ACTH.

[Ectopic ACTH secretion: a heterogeneous entity]

OBJECTIVES

ACTH-secreting non-pituitary tumors are a rare cause of Cushing's disease. We report the clinical course, prognostic aspects and molecular analysis data in three patients for whom the diagnosis was confirmed but who had variable clinical features and laboratory results.

CASE REPORTS

Patient n degree 1 had severe hypercorticism which rapidly progressed to death 13 months after diagnosis. In patient n degree 2, signs of hypercorticism severe, leading to death 5 years after discovery of the causal carcinoid tumor. Patient n degree 3 had moderate hypercorticism and has survived for more than 25 years.

DISCUSSION

These 3 ectopic tumors are representative examples of a wide range of possible ACTH-secreting ectopic tumors. In highly malignant poorly-differentiated tumors such as small-cell anaplastic carcinomas, ACTH production is aberrant and poorly controlled, and thus not particularly effective. At the other extreme, typical benign bronchial carcinomas have a high degree of neuroendocrine differentiation and secrete ACTH in a well-controlled manner difficult to distinguish from corticotropic adenomas, further exaggerating the diagnostic pitfalls.

Adrenocorticotrophic hormone-dependent Cushing's syndrome

Excess endogenous glucocorticoid production, whether ACTH dependent or ACTH independent, results in the classic clinical and biochemical picture of Cushing's syndrome. The diagnosis requires the demonstration of an increased cortisol secretion rate, best achieved by using the 24-hour UFC corrected for body surface area as an index. In mild cases, distinction from the hypercortisolism of pseudo-Cushing states may be difficult. A dexamethasone/o CRH test or close monitoring of the patient for a few months may be helpful. A discrete pituitary lesion on imaging and a standard oCRH test with results consistent with such a lesion are sufficient to proceed to trans-sphenoidal surgery. If no visible pituitary adenoma is present or if the oCRH test is equivocal, bilateral simultaneous inferior petrosal sinus sampling with oCRH administration is necessary to distinguish between a pituitary and an ectopic source. Surgical ablation is the treatment of choice for all types of Cushing's syndrome. In the 5% of cases with Cushing's disease in whom trans-sphenoidal surgery fails and in the 5% of cases in whom the disease recurs, repeat trans-sphenoidal surgery or radiation therapy in association with mitotane treatment may be pursued. Bilateral adrenalectomy effectively cures hypercortisolism if resection of the ACTH-secreting tumor is unsuccessful and radiation/medical therapy fails.

Dissociation of adrenal androgen and cortisol secretion in Cushing's syndrome

OBJECTIVES

While ACTH may modulate adrenal androgen production, there is evidence that other factors are required. Cushing's disease and ectopic ACTH secretion provide a little utilized opportunity to examine adrenal androgen levels in conditions of ACTH excess. We have compared plasma cortisol values with plasma levels of androstenedione, dehydroepiandrosterone (DHEA), DHEA-sulphate (DHEAS), testosterone and an index of free testosterone, the testosterone/sex hormone binding globulin ratio, prior to treatment in patients with Cushing's syndrome.

PATIENTS AND MEASUREMENTS

Plasma from 15 adult patients with Cushing's disease and three adults with the ectopic ACTH syndrome was obtained prior to treatment and submitted to specific immunoassays for the measurement of the above steroids.

RESULTS

Plasma cortisol values of 15 patients with Cushing's disease (range 326-1140 nmol/l, normal range 190-690 nmol/l) were elevated in 9; in contrast, plasma androstenedione (4.1-11.3 nmol/l, normal range, men 2.1-7.7, women 3.3-9.9 nmol/l) was elevated in only two patients, plasma DHEAS (3.3-17.8 mumol/l, normal range, men 4.5-18.4, women 3.5-11.8 mumol/l) was elevated in only 4 patients and plasma DHEA (4.8-45.2 nmol/l, normal range 11-48 nmol/l) was normal or low in all 15 patients. Plasma androstenedione was markedly elevated (74 nmol/l) in one of three patients with ectopic ACTH syndrome, moderately elevated in another, and normal in the third patient. In contrast, plasma DHEA and DHEAS levels were suppressed in the patient with the highest androstenedione level and low or normal in the other two patients.

CONCLUSIONS

These data suggest that ACTH alone does not control adrenal androgen secretion. The data also suggest that variability in the processing of proopiomelanocortin (the precursor of ACTH and related peptides) occurring in Cushing's disease and ectopic ACTH syndrome may account for differences in the relation of cortisol to androgens observed between the disorders and when compared to that in normal subjects.

Effective reversibility of the signs and symptoms of hypercortisolism by bilateral adrenalectomy

BACKGROUND

The long-term outcome of bilateral adrenalectomy in the management of patients with Cushing's syndrome has not been previously well studied.

METHODS

We reviewed our long-term results in 34 patients treated with bilateral adrenalectomy between 1983 and the present. Fourteen presented with occult or metastatic ectopic adrenocorticotropic hormone (ACTH) syndrome, 10 with failed treatment of Cushing's disease, five with primary micronodular and four with massive macronodular adrenocortical disease and one with indeterminate cause of Cushing's syndrome.

RESULTS

All patients underwent bilateral adrenalectomy. Of 19 patients who required antihypertensive medications before operation, 15 (79%) had significant improvement and were either off all antihypertensive medication or required less medication after operation. Of 7 patients who required medications for diabetes mellitus, after operation 6 (86%) required no medication or changed from injections to oral hypoglycemic agents. Of 9 patients with mood changes or depression, the symptoms of 8 (88%) resolved. Of 29 patients with documented weight gain, 23 (79%) showed marked weight loss. Of 13 hirsute patients, 10 (77%) had resolutions of symptoms. Of 21 patients with complaints of fatigue, the symptoms of 16 (76%) resolved. Of 8 women with amenorrhea, 6 (75%) had resolution of symptoms. Each patient in the primary adrenocortical disease group, except one with residual fatigue, had complete resolution of his or her symptoms. There was no difference in resolution of symptoms between the ectopic ACTH and Cushing's disease groups. Six patients died: in the ectopic ACTH group one died of suicide at 1 month, and four of metastatic tumor at 9, 24, 25, and 48 months, and the patient with macronodular adrenocortical hyperplasia died of a myocardial infarction at 30 months. The remainder of the patients have been followed for a mean of 32 months (3 to 67 months). None of the patients had any evidence of recurrent hypercortisolism.

CONCLUSIONS

We conclude that bilateral adrenalectomy is a safe, effective, and long-lasting method to ameliorate the devastating signs and symptoms of hypercortisolism in patients with Cushing's syndrome.

Paradoxical effect of somatostatin analogues on the ectopic secretion of corticotropin in two cases of small cell lung carcinoma

We investigated 2 patients affected with Cushing's syndrome due to the ectopic production of adrenocorticotropic hormone (ACTH) by a small cell lung carcinoma. In the 2 patients, the long-acting somatostatin analogue octreotide (100 micrograms, subcutaneously) induced a paradoxical increase in plasma ACTH and cortisol levels. In 1 patient, lanreotide, a new somatostatin analogue in a slow-release formulation (30 mg, intramuscularly), induced a similar rise in ACTH and cortisol secretion. To our knowledge, such a response has not been previously reported. Further use of somatostatin analogues in ectopic ACTH-producing tumors, especially lung tumors, requires preliminary evaluation of their therapeutic efficacy by a short test with somatostatin analogue.

Sleep architecture and sleep apnea in patients with Cushing's disease

Patients with Cushing's syndrome (CS) frequently have sleep complaints. We evaluated sleep polysomnographically in 22 patients, including 17 with pituitary-ACTH-dependent Cushing's disease (CD) and five with CS from an adrenal tumor. Data were compared to healthy controls of comparable age. Seven patients (32%) demonstrated at least mild sleep apnea (> or = 9.4 events/hour), and four of 22 (18%) had > or = 17.5 events/hour. The apneic CD and CS patients had a trend for a greater complaint of excessive daytime sleepiness. Both apneic and nonapneic groups had considerable snoring and obesity. The electroencephalographic (EEG) sleep of nonapneic patients was compared to that of normal subjects. Nonapneic CD patients differed strikingly from healthy volunteers in sleep continuity and architecture, demonstrating lighter, fragmented sleep. Rapid eye movement (REM) sleep in CD patients bore many similarities to the sleep of patients with major depression, with REM latency being significantly shortened and REM density significantly increased. Continued examination of EEG sleep in CD patients may shed light on similarities in pathophysiology between CD and major depression, disorders which are characterized by both a dysfunction of the hypothalamic-pituitary-adrenal axis and alterations in mood.

Ectopic production of ACTH and corticotropin-releasing hormone (CRH)

The most common ectopic production of a pituitary hormone is the one of ACTH leading to Cushing's syndrome. Ectopic ACTH-hypersecretion is the cause of Cushing's syndrome in 10-15% of all cases. The ACTH-secreting tumours are often oat-cell carcinomas of the lung, less frequently pancreatic cancers, hypernephromas, or C-cell carcinomas of the thyroid. Some of these tumours may be benign or semi-benign as the rare carcinoid tumours and cause great problems in the differential diagnosis of ACTH-dependent hypercortisolism. Out of 173 of our patients with Cushing's syndrome observed in the last 12 years 21 were caused by ectopic ACTH-production. Of these 21 patients 13 have a small cell carcinoma of the lung. The ectopic ACTH-syndrome often has typical clinical features caused by the levels of ACTH and cortisol leading to hypocalcemic alkalosis with muscle weakness and wasting, carbohydrate intolerance, and hypertension with oedema. The survival time in many of these patients is not long enough to allow them to develop typical signs of Cushing's syndrome though they are often highly pigmented. These patients are easily diagnosed. However, patients with small tumours which do not cause very elevated ACTH-levels and who have the more typical clinical signs of full-blown Cushing's syndrome are difficult to recognize. For the differential diagnosis of ACTH-dependent Cushing's syndrome the corticotropin-releasing hormone (CRH) stimulation test and dexamethasone suppression test with high doses are helpful. In special cases the venous sampling procedure for ACTH-measurements is necessary, also CT or NMR is helpful. Ectopic CRH-production is a rare cause of ACTH-dependent Cushing's syndrome. Patients with ectopic CRH-production and consecutive ACTH-hypersecretion from the pituitary have not been studied extensively. There are especially no well documented results of the use of the CRH-stimulation test in vivo in this group of patients with Cushing's syndrome. On the other hand, in the documented cases, not only CRH-, but also ACTH-production was found in the tumours. So far, this rare cause of ACTH-dependent Cushing's syndrome has to be excluded or confirmed by the measurement of endogenous CRH-levels. But until now we have not been able to detect one single case of ectopic CRH-production using a sensitive homologous CRH-radioimmunoassay over a period of more than 8 years in which we have seen nearly 120 newly diagnosed patients with ACTH-dependent Cushing's syndrome. Only in the plasma and tumour tissue of two patients of other groups have we found high CRH-levels.

Ectopic secretion of peptides of the proopiomelanocortin family

A wide spectrum of clinical and biochemical presentations characterize ectopic POMC syndrome. It is presently postulated that ectopic POMC production results from increased expression of the activity of a POMC gene normally occurring in a variety of tissues outside the pituitary gland. The syndrome is rapidly progressive and is characterized by severe clinical manifestations in patients with a more aggressively developing oat cell carcinoma of the lung. However, in patients with slower growing nonpituitary tumors, the presentation may overlap that seen in patients with pituitary ACTH-dependent Cushing's syndrome. In cases in which the biochemical testing results overlap with those seen in pituitary ACTH-dependent disease, a combination of lack of suppression with high-dose dexamethasone and absent response to CRH stimulation greatly increases the diagnostic accuracy. Abnormal alternative processing of POMC in nonpituitary neoplasms may render unusual POMC-derived peptides that could be used as markers in the diagnosis and follow-up of patients with this syndrome. The prognosis of patients afflicted with ectopic POMC syndrome is largely determined by the nature of the underlying tumor. However, the clinical course can be greatly modified by control of the metabolic manifestations of hypercortisolemia. A variety of surgical and pharmacologic options are available, including adrenalectomy and the use of adrenal inhibitors. Cushing's syndrome of long duration, the finding of ectopic pituitary adenomas, and the combined secretion of CRH and POMC by nonpituitary tumors constitute interesting variants of the classic picture.

An evaluation of the distinction of ectopic and pituitary ACTH dependent Cushing's syndrome by clinical features, biochemical tests and radiological findings

The efficiency of various laboratory and radiological investigations in the differentiation of ectopic from pituitary dependent Cushing's syndrome was studied, based on findings in 23 patients with verified Cushing's disease and seven patients with the ectopic ACTH syndrome. Clinical features strongly favouring the ectopic type were male sex and history for less than 18 months. Basal biochemical features strongly indicating the ectopic syndrome included plasma K+ less than 3.0 mmol/l and HCO3 greater than 30 mmol/l; serum cortisol at 9 a.m. or midnight of greater than 800 nmol/l; urine free cortisol greater than 1300 nmol/24 hours; plasma ACTH greater than 100 ng/l. In the high-dose dexamethasone suppression test, suppression by less than 50 per cent of 9 a.m. serum cortisol, urine free cortisol or 17-oxogenic steroids was usually indicative of an ectopic source of ACTH. A mean suppressed value of greater than 450 nmol/l for the 9 a.m. and midnight cortisol combined occurred in all of those with the ectopic syndrome, but in none of the 23 patients with Cushing's disease. For urine free cortisol, a mean suppressed value of less than 1000 nmol/24 hours was found in all patients with Cushing's disease, but in none of those in the ectopic group. In the metyrapone test, there was an increase of less than or equal to 3-fold in 11-deoxycortisol at 24 hours in patients with ectopic ACTH; the increase was greater than 3-fold in all but one of the patients with Cushing's disease. Failure to respond to either dexamethasone or metyrapone was found in only one of the patients with Cushing's disease (Patient 16); in the ectopic group, all patients except Patient D failed to respond to either test. It is concluded that patients presenting with clinically obvious Cushing's syndrome along with measurable plasma ACTH can be reliably divided by conventional tests into those that are driven from the pituitary and those driven by ectopic ACTH.

Corticotropin-releasing factor (CRF): stimulation in normal controls and in patients with Cushing's syndrome

Synthetic ovine and human CRF were given as an i.v. bolus to six healthy volunteers in four and two different dosages, respectively (oCRF: 25, 50, 100 and 200 micrograms; hCRF: 50 and 100 micrograms). There was a significant increase of ACTH and cortisol after the injection of all dosages though the dose-response relationship was only significant between the 50 and 100 micrograms dose of oCRF. No significant differences between ACTH and cortisol secretion after oCRF and hCRF were observed. Repetitive stimulation by hCRF led to repetitive release of identical amounts of ACTH. The CRF test with the 100 micrograms dosage was used in patients with proven Cushing's syndrome (n = 30). Results showed that the CRF test is useful in making the differential diagnosis of established Cushing's syndrome. In patients with ACTH-dependent Cushing's disease (n = 21), normal or elevated basal ACTH levels were significantly higher after stimulation by CRF compared to normal controls, with one exception. The pattern of cortisol secretion after CRF administration corresponded to the pattern of ACTH secretion in these patients. In two patients with ectopic ACTH syndrome, extremely elevated ACTH and cortisol levels did not change or showed only a small increase after CRF administration. In patients with unilateral adrenal adenoma or carcinoma (n = 7), suppressed ACTH levels did not rise after CRF administration. In addition, no significant change in cortisol secretion could be observed. After surgical removal of cortisol-producing adrenal tumors, the ACTH response to CRF can be demonstrated when cortisol levels are still undetectable. Pulsatile administration of CRF in one patient after unilateral adrenalectomy revealed that ACTH responses to CRF normalize rapidly but cannot be sustained if CRF administration is withdrawn, suggesting that the cause of adrenal failure after unilateral adrenalectomy for Cushing's syndrome or with long-term corticoid therapy is due to hypothalamic CRF deficiency. The suppression of ACTH responses to CRF in glucocorticoid-treated patients correlated with the daily corticoid dosage. Since the ACTH hyper-response to CRF in six patients with Cushing's disease was suppressed by short-term dexamethasone treatment, the pituitary as a target site for feedback inhibition also was demonstrated.

Dissociation between plasma adrenal androgens and cortisol in Cushing's disease and ectopic ACTH-producing tumour: relation to adrenarche

To assess the effect of chronic hypersecretion of corticotropin (ACTH) and other peptides derived from proopiomelanocortin , and of cortisol, on plasma adrenal androgen concentration, plasma dehydroepiandrosterone sulphate (DHEA-S), dehydroepiandrosterone (DHEA), androstenedione (delta 4 A), and cortisol were measured in 14 children and adolescents with Cushing's disease, a 9-year-old boy with an ectopic ACTH-producing tumour, and a group of normal, age-related individuals. The plasma DHEA-S concentration was normal for chronological age in 9 of 12 patients and for bone age in 7 of 10 patients. The plasma DHEA level was normal for chronological age in 12 of 14 patients and for bone age in 8 of 10 patients. In contrast, the concentration of plasma delta 4 A was raised for chronological age in 6 of 13 patients and for bone age in 7 of 10 patients. All patients had raised plasma cortisol levels in the afternoon and other laboratory and clinical signs of hypercortisolism. In the boy with an ectopic ACTH-producing tumour, plasma DHEA-S was moderately raised, plasma DHEA was normal, and plasma delta 4 A was very high. This patient's plasma ACTH levels ranged from 1340 to 1520 pg/ml and the cortisol levels from 51 to 95 micrograms/dl. The findings suggest that a factor other than ACTH is also required for adrenal androgen secretion. Since the other proopiomelanocortin -related peptides--ie, the N-terminal peptide (1-76), beta-endorphin (beta-EP), beta-lipotropin (beta-LPH), and gamma-lipotropin (gamma-LPH)--are raised in the plasma of patients with Cushing's disease, one of these is unlikely to be that putative factor.

Immunocytochemical evidence for the presence of gamma 1-MSH-like immunoreactivity in pituitary corticotrophs and ACTH-producing tumours

The presence of gamma 1-MSH has been demonstrated in bovine neuro-intermediate lobe by biochemical methods, thus suggesting that this peptide is cleaved from the cryptic region of pro-opiocortin. In this study we report the localisation of gamma 1-MSH-like immunoreactivity in the adenohypophysis of man, ox, pig, dog and guinea-pig using immunocytochemical procedures at both light and electron microscope levels. Antisera recognising the C-terminal Arg-Phe-amide and the C-terminal penta-peptide-amide of gamma 1-MSH have been used throughout this study. The immunostaining was found in all endocrine cells of the pars intermedia (where present) and in scattered cells of the pars distalis identified as corticotrophs. No gamma 1-MSH immunoreactivity was detected in rat adenohypophysis. In addition, 7 ACTH-producing tumours (1 pituitary adenoma and 6 ectopic) were investigated and shown to contain gamma 1-MSH immunoreactive cells.