A case series of bilateral inferior petrosal sinus sampling with desmopressin in evaluation of ACTH-dependent Cushing's syndrome in Iran

Diagnostic Accuracy of the Desmopressin Stimulation Test in the Comprehensive Assessment of ACTH-Dependent Cushing's Syndrome: A Comparative Analysis with BIPSS and TSS

BACKGROUND

Cushing's syndrome (CS) poses diagnostic challenges, particularly in distinguishing pituitary-dependent Cushing's syndrome, Cushing's disease (CD), from the ectopic ACTH syndrome (EAS). This study evaluated the diagnostic value of the desmopressin stimulation test (DST) in patients with ACTH-dependent CS in helping this discrimination.

METHODS

Twenty-three ACTH-dependent CS patients underwent sequential DST, bilateral inferior petrosal sinus sampling (BIPSS), and transsphenoidal surgery (TSS). Two definitions of a positive DST results were applied. Diagnostic performance was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios. To avoid bias from predetermined criteria, we generated univariate receiver-operating characteristic (ROC) curves, plotting sensitivity against 1-specificity at various percentage cortisol and ACTH response levels.

RESULTS

Against BIPSS, DST demonstrated robust sensitivity (Definition 1: 90.0%, Definition 2: 76.2%) and overall accuracy (Definition 1: 87.0%, Definition 2: 73.9%). PPV was high (Definition 1: 95.0%, Definition 2: 94.1%), but NPV indicated potential false negatives. Compared to TSS, DST showed good sensitivity (Definition 1: 90.9-77.3%) and PPV (100.0%) but limited NPV (16.7%). The likelihood ratios emphasized the diagnostic value of the test. Notably, against TSS, DST showed perfect discriminatory power (AUC 1.000 for percent ACTH, 0.983 for percent cortisol).

CONCLUSION

The desmopressin test shows promise in accurately identifying the underlying cause of ACTH-dependent CS, potentially reducing the reliance on invasive procedures and providing a practical solution for managing complex cases. Further research with larger cohorts is required to validate the utility of the DST in routine clinical practice.

Bilateral inferior petrosal sinus sampling in the differential diagnosis of ACTH-dependent Cushing's syndrome: A reappraisal

Cushing's syndrome (CS) is a rare disorder, once exogenous causes have been excluded. However, when diagnosed, the majority of cases are adrenocorticotropic hormone (ACTH)-dependent, of which a substantial minority are due to a source outside of the pituitary, ectopic ACTH syndrome (EAS). Differentiating among pituitary-dependent CS, Cushing's disease (CD) and an ectopic source can be problematic. Because non-invasive tests in the evaluation of CS patients often lack adequate sensitivity and specificity, bilateral inferior petrosal sinus sampling (BIPSS), a minimally invasive procedure performed during the investigation of ACTH-dependent CS, can be extremely helpful. BIPSS is considered to be the gold standard for differentiating CD from the EAS. Furthermore, although such differentiation may indeed be challenging, BIPSS is itself a complex investigation, especially in recent times due to the widespread withdrawal of corticotrophin-releasing hormone and its replacement by desmopressin. We review current published data on this investigation and, in the light of this and our own experience, discuss its appropriate use in diagnostic algorithms.

Comparison of the preoperative diagnostic accuracy of BIPSS versus MRI for Cushing disease: a single-centre experience

BACKGROUND

Cushing disease (CD) arises due to a pituitary corticotroph adenoma, which is the most common cause of Cushing syndrome (CS). Bilateral inferior petrosal sinus sampling (BIPSS) is a safe method for differentiating CD from ectopic adrenocorticotropic hormone (ACTH)-dependent CS. Enhanced high-resolution magnetic resonance imaging (MRI) can localize tiny pituitary lesions. The aim of this study was to compare the preoperative diagnostic accuracy of BIPSS versus MRI for CD in CS patients. We performed a retrospective study of patients who underwent BIPSS and MRI between 2017 and 2021. Low- and high-dose dexamethasone suppression tests were performed. Blood samples were collected simultaneously from the right and left catheter and femoral vein before and after desmopressin stimulation. MRI images were obtained, and endoscopic endonasal transsphenoidal surgery (EETS) was performed in confirmed CD patients. Dominant sides of ACTH secretion during BIPSS and MRI were compared with surgical findings.

RESULTS

Twenty-nine patients underwent BIPSS and MRI. CD was diagnosed in 28 patients, 27 of whom received EETS. Localizations of microadenomas by MRI and BIPSS agreed with the EETS findings in 96% and 93% of the cases, respectively. BIPSS and EETS were successfully performed on all patients.

CONCLUSION

BIPSS was the most accurate method (gold standard) for establishing a preoperative diagnosis of pituitary-dependent CD and was more sensitive than MRI in diagnosing microadenoma. High-resolution MRI with enhancement had an advantage over BIPSS in microadenoma lateralization diagnostics. The combined use of MRI and BIPSS could improve the preoperative diagnosis accuracy in ACTH-dependent CS patients.

Diagnostic accuracy of bilateral inferior petrosal sinus sampling using desmopressin or corticotropic- releasing hormone in ACTH-dependent Cushing's syndrome: A systematic review and meta-analysis

The current gold standard diagnostic method for Cushing disease (CD) is bilateral inferior petrosal sinus sampling (BIPSS) after corticotropin-releasing hormone (CRH) stimulation. Due to shortages of CRH, BIPSS has been performed with desmopressin (DDAVP) instead. The objective of this systematic review and meta-analysis was to estimate the diagnostic accuracy of BIPSS using DDAVP or CRH for the differential diagnosis of Cushing's syndrome (CS). A literature review was done in PubMed, Scopus, EMBASE, and google scholar databases to derive summary estimates of the overall diagnostic sensitivity and accuracy of BIPSS using DDAVP or CRH in Cushing's syndrome. Pooled sensitivity, specificity, diagnostic odds ratio and summary receiver operating characteristic curves (SROC) for differential diagnosis of Cushing's syndrome in the random-effects models, were computed. Overall, 11 different studies with a total of 612 participants, were eligible for the analysis. Five articles with data on BIPSS using DDAVP, 5 papers on BIPSS using CRH, and another one evaluated the results of stimulation using DDAVP, with or without CRH, for differential diagnosis of Cushing's syndrome. The pooled (95% CI) sensitivity and specificity of BIPSS using DDAVP, were 96% (91-98%) and 1.00 (0.00-1.00), respectively. The area under the SROC curve was 0.95. The pooled (95% CI) sensitivity and specificity of BIPSS using CRH, were 98% (92-99%) and 1.00 (0.00-1.00), respectively, and the area under the SROC curve was 0.98. The I² index (95% CI) was 0% (0-100%) for both BIPSS using DDAVP and using CRH. As a result, DDAVP stimulation is a safe, effective, less expensive, valuable and available alternative to CRH in the setting of BIPSS for all age groups of patients with CS. Registration code in PROSPERO: CRD42021292531.

Recurrence of a neuroendocrine tumor of adrenal origin: a case report with more than a decade follow-up

BACKGROUND

Neuroendocrine tumor (NET) with adrenocorticotropic hormone (ACTH) secretion are very rare. To our knowledge, no follow-up study is published for ACTH-secreting NET, regardless of the primary site, to show second occurrence of tumor after a long follow-up, following resection of primary tumor.

CASE PRESENTATION

Here, we describe a 49-year-old-man with cushingoid feature, drowsiness and quadriparesis came to emergency department at December 2005. Laboratory tests revealed hyperglycemia, metabolic alkalosis, severe hypokalemia, and chemical evidence of an ACTH-dependent hypercortisolism as morning serum cortisol of 57 μg /dL without suppression after 8 mg dexamethasone suppression test, serum ACTH level of 256 pg/mL, and urine free cortisol of > 1000 μg /24 h. Imaging showed only bilateral adrenal hyperplasia, without evidence of pituitary adenoma or ectopic ACTH producing tumors. Importantly, other diagnostic tests for differentiating Cushing disease (CD) from ectopic ACTH producing tumor, such as inferior petrosal sinus sampling (IPSS), corticotropin releasing hormone (CRH) stimulation test, octreotide scan or fluorodeoxyglucose (FDG)-positron emission tomography (PET) scan were not available in our country at that time. Therefore, bilateral adrenalectomy was performed that led to clinical and biochemical remission of hypercortisolism and decreased ACTH level to < 50 pg/mL, findings suggestive of a primary focus of NET in adrenal glands. After 11 years uncomplicated follow up, the ACTH level elevated up to 341 pg/mL and re-evaluation showed a 2 cm nodule in the middle lobe of the right lung. Surgical excision of the pulmonary nodule yielded a carcinoid tumor with positive immunostaining for ACTH; leading to decrease in serum ACTH level to 98 pg/mL. Subsequently after 7 months, serum ACHT levels rose again. More investigation showed multiple lung nodules with metastatic bone lesions accompanied by high serum chromogranin level (2062 ng/mL), and the patient managed as a metastatic NET, with bisphosphonate and somatostatin receptor analogues.

CONCLUSION

This case of surgically-treated NET showing a secondary focus of carcinoid tumor after one decade of disease-free follow-up emphasizes on the importance of long-term follow-up of ACTH-secreting adrenal NET.