Ioannis Ilias

The diagnosis and management of malignant phaeochromocytoma and paraganglioma

Malignant phaeochromocytomas are rare tumours accounting for ~10% of all phaeochromocytomas; the prevalence of malignancy among paragangliomas is higher, especially those associated with succinate dehydrogenase subunit B gene mutations. Although a subset of these tumours has metastatic disease at initial presentation, a significant number develops metastases during follow-up after excision of an apparently benign tumour. Clinical, biochemical and histological features cannot reliably distinguish malignant from benign tumours. Although a number of recently introduced molecular markers have been explored, their clinical significance remains to be elucidated from further studies. Several imaging modalities have been utilised for the diagnosis and staging of these tumours. Functional imaging using radiolabelled metaiodobenzylguanidine (MIBG) and more recently, (18)F-fluorodopamine and (18)F-fluorodopa positron emission tomography offer substantial sensitivity and specificity to correctly detect metastatic phaeochromocytoma and paraganglioma and helps identify patients suitable for treatment with radiopharmaceuticals. The 5-year mortality rate of patients with malignant phaeochromocytomas and paragangliomas greater than 50% indicates that there is considerable room for the improvement of currently available therapies. The main therapeutic target is tumour reduction and control of symptoms of excessive catecholamine secretion. Currently, the best adjunctive therapy to surgery is treatment with radiopharmaceuticals using (131)I-MIBG; however, this is very rarely curative. Chemotherapy has been used for metastatic disease with only a partial and mainly palliative effect. The role of other forms of radionuclide treatment either alone or in combination with chemotherapy is currently evolving. Ongoing microarray studies may provide novel intracellular pathways of importance for proliferation/cell cycle control, and lead to the development of novel pharmacological agents.

The optimal imaging of adrenal tumours: a comparison of different methods

Computed tomography (CT; unenhanced, followed by contrast-enhanced examinations) is the cornerstone of imaging of adrenal tumours. Attenuation values of <10 Hounsfield units on an unenhanced CT are practically diagnostic for adenomas. When lesions cannot be characterised adequately with CT, magnetic resonance imaging (MRI) evaluation (with T1- and T2-weighted sequences and chemical shift and fat-suppression refinements) is sought. Functional nuclear medicine imaging is useful for adrenal lesions that are not adequately characterised with CT and MRI. Scintigraphy with [(131)I]-6-iodomethyl norcholesterol (a labelled cholesterol analogue) can differentiate adrenal cortical adenomas from carcinomas. Phaeochromocytomas appear as areas of abnormal and/or increased uptake of [(123)I]- and [(131)I]-meta-iodobenzylguanidine (a labelled noradrenaline analogue). The specific and useful roles of adrenal imaging include the characterisation of tumours, assessment of true tumour size, differentiation of adenomas from carcinomas and metastases, and differentiation of hyperfunctioning from non-functioning lesions. Adrenal imaging complements and assists the clinical and hormonal evaluation of adrenal tumours.

Association of Hypertension and Hypokalemia with Cushing's Syndrome Caused by Ectopic ACTH Secretion

Abstract: Cushings syndrome is associated with hypertension in approximately 80% of cases. Hypertension contributes to the marked increased mortality risk of past or current Cushings syndrome, largely because of increased cardiovascular risk. Observation of the pathophysiological effect of chronically elevated ACTH and cortisol values in patients with ectopic ACTH secretion complements the available data from acute studies of the effects of ACTH and glucocorticoid infusions in normal volunteers. In a retrospective case review, we identified 58 patients with Cushings syndrome caused by ectopic ACTH secretion, who were treated at the National Institutes of Health between 1983‐1997. The diagnosis of an ectopic ACTH cause was confirmed by inferior petrosal sinus sampling and/or pathologic examination of tumor. The commonest causes were bronchial carcinoid (40%) and thymic carcinoid (10%), but 18 of 58 (31%) patients had an unknown source of ectopic ACTH. Hypertension (systolic blood pressure >140 mmHg and/or diastolic blood pressure >90 mmHg in adults) was noted in 45 of 58 (78%) ectopic Cushings patients, a prevalence similar to that noted in other endogenous Cushings syndrome etiologies. Hypertension was severe, deemed to require 3 or more drugs by the treating physicians, in 26 of 58 (45%) patients. Hypokalemia was much more prevalent than in patients with other causes of Cushings syndrome, affecting 33 of 58 (57%) patients. The range of plasma ACTH (17‐1557 pg/mL, normal <60) and 24‐hour urine cortisol (UC) excretion (192‐1600 mcg/24 hr, normal <90) allowed analysis of the influence of these hormones on blood pressure and plasma potassium. There was a significant relationship between 24‐hour UC excretion and the presence of hypokalemia (P= 0.003). Eight of nine patients with a UC >6000 mcg/24 hr had hypokalemia. There was no relation between ACTH level and hypokalemia. In addition, we did not find blood pressure severity to be related to UC excretion or ACTH levels. Urine and plasma cortisol and cortisol metabolite measurements suggest that cortisol may act as a mineralocorticoid when in excess, perhaps by saturating the 11β‐hydroxysteroid‐dehydrogenase (11β‐HSD2 enzyme) that inactivates cortisol at the renal tubule. The current data suggest that high cortisol levels may be the principal cause of hypokalemic alkalosis in Cushings syndrome, rather than inhibition of the 11βHSD2 enzyme by ACTH or the effects of adrenal steroid biosynthetic intermediaries with mineralococorticoid activity.

Comparison of 6-18F-Fluorodopamine PET with 123I-Metaiodobenzylguanidine and 111In-Pentetreotide Scintigraphy in Localization of Nonmetastatic and Metastatic Pheochromocytoma

We compared functional imaging modalities including PET with 6-18F-fluorodopamine (18F-DA) with 123I-metaiodobenzylguanidine (123I-MIBG) and somatostatin receptor scintigraphy (SRS) with 111In-pentetreotide in nonmetastatic and metastatic pheochromocytoma (PHEO). Methods: We studied 25 men and 28 women (mean age ± SD, 44.2 ± 14.2 y) with biochemically proven nonmetastatic (n = 17) or metastatic (n = 36) PHEO. Evaluation included anatomic imaging with CT or MRI and functional imaging that included at least 2 nuclear medicine modalities: 18F-DA PET, 123I-MIBG scintigraphy, or SRS. Sensitivity of functional imaging versus anatomic imaging was assessed on a per-patient and a per-region basis. Results: For this available cohort, on a per-patient basis overall sensitivity (combined for nonmetastatic and metastatic PHEO) was 90.2% for 18F-DA PET, 76.0% for 123I-MIBG scintigraphy, and 22.0% for SRS. On a per-region basis, overall sensitivity was 75.4% for 18F-DA PET, 63.4% for 123I-MIBG scintigraphy, and 64.0% for SRS. Conclusion: If available, 18F-DA PET should be used in the evaluation of PHEO, because it is more sensitive than 123I-MIBG scintigraphy or SRS. If 18F-DA PET is not available, 123I-MIBG scintigraphy (for nonmetastatic or adrenal PHEO) and SRS (for metastatic PHEO) should be the first alternative imaging methods to be used.

Hypothalamic-pituitary-adrenal axis dysfunction in critically ill patients with traumatic brain injury: incidence, pathophysiology, and relationship to vasopressor dependence and peripheral interleukin-6 levels.

ObjectiveTo investigate hypothalamic-pituitary-adrenal axis function in patients requiring mechanical ventilation for traumatic brain injury and to assess the relation of hypothalamic-pituitary-adrenal axis abnormalities with vasopressor dependence and peripheral cytokine levels. DesignProspective study. SettingGeneral intensive care unit in a university teaching hospital. PatientsForty patients (33 men and 7 women) with moderate to severe traumatic brain injury (mean age, 37 ± 16 yrs) were studied the day after termination of mechanical ventilation (7–60 days after trauma). InterventionsFirst, a morning blood sample was obtained to measure baseline cortisol, corticotropin, interleukin-6, and tumor necrosis factor alpha. Subsequently, 1 &mgr;g of synthetic corticotropin was injected intravenously, and 30 mins later, a second blood sample was drawn to determine stimulated plasma cortisol. Based on data derived from healthy volunteers, patients having stimulated cortisol levels <18 &mgr;g/dL were defined as nonresponders to the low-dose stimulation test. Thirty-one patients underwent also a human corticotropin releasing hormone test. Measurements and Main ResultsIn traumatic brain injury patients, mean baseline and low-dose stimulation test-stimulated cortisol levels were 17.2 ± 5.4 &mgr;g/dL and 24.0 ± 6.6 &mgr;g/dL, respectively. The median increment in cortisol was 5.9 &mgr;g/dL. Basal corticotropin levels ranged from 3.9 to 118.5 pg/mL. Six of the 40 patients (15%) failed the low-dose stimulation test. The human corticotropin releasing hormone test (performed in 26 responders and five nonresponders) revealed diminished cortisol release only in the low-dose stimulation test nonresponder patients. Corticotropin responses to corticotropin releasing hormone were consistent with both primary (three patients) and/or secondary (two patients) adrenal dysfunction. In retrospect, nonresponders to the low-dose stimulation test more frequently required vasopressors (6/6 [100%] vs. 16/34 [47%]; p = .02) and for a longer time interval (median, 0 vs. 293 hrs; p = .006) compared with responders. Furthermore, nonresponders had higher interleukin-6 levels compared with responders (56.03 vs. 28.04 pg/mL; p = .01), whereas tumor necrosis factor alpha concentrations were similar in the two groups (2.42 vs. 1.55 pg/mL; p = .53). ConclusionsAdrenal cortisol secretion after dynamic stimulation is deficient in a subset of critically ill patients with moderate to severe head injury. This disorder is associated with prior vasopressor dependency and higher interleukin-6 levels.

Biochemical diagnosis, localization and management of pheochromocytoma: focus on multiple endocrine neoplasia type 2 in relation to other hereditary syndromes and sporadic forms of the tumour

Approximately 50% of patients with multiple endocrine neoplasia (MEN) 2A or 2B develop pheochromocytoma. These tumours are almost exclusively benign and localized in the adrenal glands. About one‐third are bilateral at initial diagnosis. Amongst patients with pheochromocytoma, those with MEN 2A have subtler symptoms compared to those with sporadic disease. Since pheochromocytomas in patients with MEN 2 often secrete catecholamines episodically (but metabolize them continuously to metanephrines), the first choice for biochemical diagnosis is the measurement of free metanephrines in plasma, with urinary fractionated metanephrines being the second choice. In patients with pheochromocytomas that produce exclusively normetanephrine, MEN 2 can be excluded. In patients with biochemically proven MEN 2‐related pheochromocytoma, anatomical imaging of the adrenals (with either computerized tomography or magnetic resonance) should be obtained next. Functional imaging with specific ligands (e.g. scintigraphy with [123I]‐metaiodobenzylguanidine or, if available, positron emission tomography with [18F]‐fluorodopamine, [18F]‐dihydroxyphenylalanine, [11C]‐adrenaline or [11C]‐hydroxyephedrine) may then be particularly useful in patients with distorted anatomy from previous surgery, in cases of equivocal biochemical data despite high clinical suspicion for a tumour, to rule out multifocal disease, or where there is suspicion of metastatic disease (e.g. tumours larger than 5 cm). Laparoscopic surgery is the treatment of choice and subtotal (cortical‐sparing) adrenalectomy is the procedure of choice in bilateral pheochromocytomas.

High prevalence of decreased cortisol reserve in brain-dead potential organ donors.

ObjectiveTo investigate the adrenocortical function in brain-dead patients, potential organ donors. DesignProspective study. SettingIntensive care units in two teaching hospitals. PatientsA total of 37 patients (28 men, nine women) with severe brain injury, having a mean age of 42 ± 18 yrs, were included in the study. Group A consisted of 20 brain-injured patients who did not deteriorate to brain death. Group B included 17 brain-injured patients who were brain dead; of these, ten patients developed brain death during ICU stay and seven patients were admitted to the ICU after clinical brain death. InterventionsIn all patients (group A and group B), a morning blood sample was obtained at admission to the ICU to determine baseline plasma cortisol. Subsequently, 1 &mgr;g of corticotropin (adrenocorticotropic hormone, Synacthen) was administered intravenously, and a blood sample was taken 30 mins after the injection. In group B patients who became brain dead while being treated in the ICU (n = 10), the same procedure was repeated the morning after the confirmation of brain death. Patients having a cortisol level of at least 18 &mgr;g/dL after the administration of adrenocorticotropic hormone were defined as responders. Measurements and Main ResultsAfter the occurrence of brain death, group B patients had significantly lower values for baseline (8.5 ± 6.2 vs. 17.0 ± 6.6 &mgr;g/dL, p < .001) and stimulated (16.9 ± 6.3 vs. 23.9 ± 5.7 &mgr;g/dL, p = .001) plasma cortisol compared with group A patients. Thirteen group B patients (76%) and two group A patients (10%) were nonresponders to adrenocorticotropic hormone (p < .001). In group B patients, baseline and stimulated cortisol concentrations were significantly related (r = .71, p = .001), whereas there was no correlation between baseline cortisol and the increment in cortisol (r = −.37, p = .15). Mean hormonal data of the ten brain-dead patients studied at admission in the ICU and after the occurrence of brain death were the following: baseline plasma cortisol (23.5 ± 11.4 vs. 6.8 ± 4.2 &mgr;g/dL, p = .003) and stimulated serum cortisol (28.8 ± 9.9 vs. 16.3 ± 4.3 &mgr;g/dL, p = .008). ConclusionsAdrenal cortisol secretion after dynamic stimulation is deficient in a substantial proportion of brain-dead potential organ donors.

New functional imaging modalities for chromaffin tumors, neuroblastomas and ganglioneuromas

Nuclear medicine modalities use radiolabeled ligands that either follow metabolic pathways or act on cellular receptors. Thus, they permit functional imaging of physiological processes and help to localize sites such as tumors that harbor pathological events. The application of positron emission tomography (PET) ligands to the specific pathways of synthesis, metabolism and inactivation of catecholamines found in chromaffin tumors, neuroblastomas and ganglioneuromas can be used to provide a more thorough localization of these types of tumor. Recent advances have been made in functional imaging to localize pheochromocytomas, paragangliomas, neuroblastomas and ganglioneuromas, including approaches based on PET with [(18)F]fluorodopamine, [(18)F]fluorohydroxyphenylalanine, [(11)C]epinephrine or [(11)C]hydroxyephedrine. Such functional imaging can complement computed tomography or magnetic resonance imaging and other scintigraphic techniques to localize these tumors before surgical or medical therapeutic approaches are considered.

Interleukin-6: a cytokine and/or a major modulator of the response to somatic stress.

Abstract:  The hypothalamic‐pituitary‐adrenal (HPA) axis and the proinflammatory cytokines (and interleukin‐6 [IL‐6] in particular) are enmeshed in the response to somatic stress, either in health or in acute or chronic disease. Usually IL‐6 is elevated in states of septic (such as sepsis) or aseptic inflammation (such as rheumatoid arthritis). Exercise is a form of somatic stress. Local tissue IL‐6 elevation is noted during shorter and less intense exercise, whereas brief peripheral IL‐6 “bursts” are observed with longer and more intense exercise. Therapeutic interventions that target IL‐6 or its soluble receptor are currently assessed, with an emphasis on autoimmune diseases and inflammatory conditions.

A clinical overview of pheochromocytomas/paragangliomas and carcinoid tumors.

Pheochromocytomas/paragangliomas are rare tumors; most are sporadic. Biochemical proof of disease is better with measurement of plasma metanephrines and less cumbersome than determinations in urine; its implementation is expanding. Anatomical imaging with computed tomography or magnetic resonance imaging should be followed by functional (nuclear medicine) imaging: chromaffin tumor-specific methods are preferred. Treatment is surgical; for nonoperable disease other options are available. Overall 5-year survival is 50%. Carcinoid tumors derive from serotonin-producing enterochromaffin cells in the fore-, mid- or hindgut. Biochemical screening (and follow-up) is done with measurements of 5-hydroxyindoloacetic acid in urine. For most carcinoids, functional imaging is better than other modalities in localizing primary tumors. Surgery is the treatment of choice; nonresectable tumors are treated with somatostatin analogs or chemotherapy. Overall 5-year survival for patients with carcinoids is 67%.