Cushing's disease: predicting long-term remission after surgical treatment.

Cushing's disease (CD) is a state of excess glucocorticoid production resulting from an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma. The gold-standard treatment for CD is transsphenoidal adenomectomy. In the hands of an experienced neurosurgeon, gross-total resection is possible in the majority of ACTH-secreting pituitary adenomas, with early postoperative remission rates ranging from 67% to 95%. In contrast to the strong data in support of resection, the clinical course of postsurgical persistent or recurrent disease remains unclear. There is significant variability in recurrence rates, with reports as high as 36% with a mean time to recurrence of 15-50 months. It is therefore important to develop biochemical criteria that define postsurgical remission and that may provide prognosis for long-term recurrence. Despite the use of a number of biochemical assessments, there is debate regarding the accuracy of these tests in predicting recurrence. Here, the authors review the various biochemical criteria and assess their utility in predicting CD recurrence after resection.

Pitfalls in the diagnosis and management of Cushing's syndrome.

Despite many recent advances, the management of patients with Cushing's disease continues to be challenging. Cushing's syndrome is a complex metabolic disorder that is a result of excess glucocorticoids. Excluding the exogenous causes, adrenocorticotropic hormone-secreting pituitary adenomas account for nearly 70% of all cases of Cushing's syndrome. The suspicion, diagnosis, and differential diagnosis require a logical systematic approach with attention paid to key details at each investigational step. A diagnosis of endogenous Cushing's syndrome is usually suspected in patients with clinical symptoms and confirmed by using multiple biochemical tests. Each of the biochemical tests used to establish the diagnosis has limitations that need to be considered for proper interpretation. Although some tests determine the total daily urinary excretion of cortisol, many others rely on measurements of serum cortisol at baseline and after stimulation (e.g., after corticotropin-releasing hormone) or suppression (e.g., dexamethasone) with agents that influence the hypothalamic-pituitary-adrenal axis. Other tests (e.g., measurements of late-night salivary cortisol concentration) rely on alterations in the diurnal rhythm of cortisol secretion. Because more than 90% of the cortisol in the circulation is protein bound, any alteration in the binding proteins (transcortin and albumin) will automatically influence the measured level and confound the interpretation of stimulation and suppression data, which are the basis for establishing the diagnosis of Cushing's syndrome. Although measuring late-night salivary cortisol seems to be an excellent initial test for hypercortisolism, it may be confounded by poor sampling methods and contamination. Measurements of 24-hour urinary free-cortisol excretion could be misleading in the presence of some pathological and physiological conditions. Dexamethasone suppression tests can be affected by illnesses that alter the absorption of the drug (e.g., malabsorption, celiac disease) and by the concurrent use of medications that interfere with its metabolism (e.g., inducers and inhibitors of the P450 enzyme system). In this review, the authors aim to review the pitfalls commonly encountered in the workup of patients suspected to have hypercortisolism. The optimal diagnosis and therapy for patients with Cushing's disease require the thorough and close coordination and involvement of all members of the management team.

Corticotroph hyperplasia and Cushing disease: diagnostic features and surgical management.

OBJECTIVE: This study was done to compare corticotroph hyperplasia and histopathologically proven adenomas in patients with Cushing disease by analyzing diagnostic features, surgical management, and clinical outcomes. METHODS: Patients with suspected pituitary Cushing disease were included in a retrospective cohort study and were excluded if results of pathological analysis of the surgical specimen were nondiagnostic or normal. Cases were reviewed by two experienced neuropathologists. Total lesion removal was used as a dichotomized surgical variable; it was defined as an extracapsular resection (including a rim of normal gland) in patients with an adenoma, and for hyperplasia patients it was defined as removal of the presumed lesion plus a rim of surrounding normal gland. Bivariate and multivariate analyses were performed. Recurrence-free survival was compared between the two groups. RESULTS: The final cohort consisted of 63 patients (15 with hyperplasia and 48 with adenoma). Normal pituitary acinar architecture was highly variable. Corticotroph hyperplasia was diagnosed based on the presence of expanded acini showing retained reticulin architecture and predominant staining for adrenocorticotropic hormone. Crooke's hyaline change was seen in 46.7% of specimens, and its frequency was equal in nonlesional tissue of both groups. The two groups differed only by MRI findings (equivocal/diffuse lesion in 46% of hyperplasia and 17% of adenoma; p = 0.03). Diagnostic uncertainty in the hyperplasia group resulted in additional confirmatory testing by 24-hour urinary free cortisol. Total lesion removal was infrequent in patients with hyperplasia compared to those with adenoma (33% vs 65%; p = 0.03). Initial biochemical remission was similar (67% in hyperplasia and 85% in adenoma; p = 0.11). There was no difference in hypothalamic-pituitary-adrenal axis recovery or disease recurrence. The median follow-up was 1.9 years (IQR 0.7-7.6 years) for the hyperplasia group and 1.2 years (IQR 0.4-2.4 years) for the adenoma group. Lack of a discrete lesion and diagnostic uncertainty were the only significant predictors of hyperplasia (sensitivity 53.3%, specificity 97.7%, positive predictive value 88.9%, negative predictive value 85.7%). An adjusted Cox proportional hazards model showed similar recurrence-free survival in the two groups. CONCLUSIONS: This study suggests an association between biochemically proven Cushing disease and histopathologically proven corticotroph hyperplasia. Imaging and operative findings can be ambiguous, and, compared to typical adenomas with a pseudocapsule, the surgical approach is more nuanced. Nevertheless, if treated appropriately, biochemical outcomes may be similar.