Pulmonary arterial sampling was useful for localizing ectopic ACTH production in a patient with bronchial carcinoid causing Cushing syndrome

Evaluating the usefulness of plasma chromogranin A measurement in cyclic ACTH-dependent Cushing's syndrome

Cushing's syndrome, a clinical condition characterized by hypercortisolemia, exhibits distinct clinical signs and is associated with cyclic cortisol secretion in some patients. The clinical presentation of cyclic Cushing's syndrome can be ambiguous and its diagnosis is often challenging. We experienced a 72-year-old woman with cyclic ACTH-dependent Cushing's syndrome caused by a pulmonary carcinoid tumor. Diagnosis was challenging because of the extended trough periods, and the responsible lesion was initially unidentified. A subsequent follow-up computed tomography revealed a pulmonary lesion, and ectopic ACTH secretion from this lesion was confirmed by pulmonary artery sampling. Despite the short peak secretion period of ACTH (approximately one week), immunostaining of the surgically removed tumor confirmed ACTH positivity. Interestingly, stored plasma chromogranin A levels were elevated during both peak and trough periods. The experience in evaluating this patient prompted us to investigate the potential use of plasma chromogranin A as a diagnostic marker of ACTH-dependent Cushing's syndrome. A retrospective study was conducted to determine the efficacy of plasma chromogranin A in three patients with ectopic ACTH syndrome (EAS), including the present case, and six patients with Cushing's disease (CD) who visited our hospital between 2018 and 2021. Notably, plasma chromogranin A levels were higher in patients with EAS than in those with CD. Additionally, a chromogranin A level in the present case during the trough phase was lower than that in the peak phase, and was similar to those in CD patients. The measurement of plasma chromogranin A levels could aid in differentiating EAS from CD.

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.

Cushing Syndrome: Diagnostic Workup and Imaging Features, With Clinical and Pathologic Correlation

OBJECTIVE

Cushing syndrome (CS) is a constellation of clinical signs and symptoms resulting from chronic exposure to excess cortisol, either exogenous or endogenous. Exogenous CS is most commonly caused by administration of glucocorticoids. Endogenous CS is subdivided into two types: adrenocorticotropic hormone (ACTH) dependent and ACTH independent.

CONCLUSION

Cushing disease, which is caused by a pituitary adenoma, is the most common cause of ACTH-dependent CS for which pituitary MRI can be diagnostic, with bilateral inferior petrosal sinus sampling useful in equivocal cases. In ectopic ACTH production, which is usually caused by a tumor in the thorax (e.g., small cell lung carcinoma, bronchial and thymic carcinoids, or medullary thyroid carcinoma) or abdomen (e.g., gastroenteropancreatic neuroendocrine tumors or pheochromocytoma), CT, MRI, and nuclear medicine tests are used for localizing the source of ACTH. In ACTH-independent CS, which is caused by various adrenal abnormalities, adrenal protocol CT or MRI is usually diagnostic.

GEP-NETS update: functional localisation and scintigraphy in neuroendocrine tumours of the gastrointestinal tract and pancreas (GEP-NETs)

For patients with neuroendocrine tumours (NETs) of the gastrointestinal tract and pancreas (GEP) (GEP-NETs), excellent care should ideally be provided by a multidisciplinary team of skilled health care professionals. In these patients, a combination of nuclear medicine imaging and conventional radiological imaging techniques is usually mandatory for primary tumour visualisation, tumour staging and evaluation of treatment. In specific cases, as in patients with occult insulinomas, sampling procedures can provide a clue as to where to localise the insulin-hypersecreting pancreatic NETs. Recent developments in these fields have led to an increase in the detection rate of primary GEP-NETs and their metastatic deposits. Radiopharmaceuticals targeted at specific tumour cell properties and processes can be used to provide sensitive and specific whole-body imaging. Functional imaging also allows for patient selection for receptor-based therapies and prediction of the efficacy of such therapies. Positron emission tomography/computed tomography (CT) and single-photon emission CT/CT are used to map functional images with anatomical localisations. As a result, tumour imaging and tumour follow-up strategies can be optimised for every individual GEP-NET patient. In some cases, functional imaging might give indications with regard to future tumour behaviour and prognosis.