Nelson’s syndrome after bilateral adrenalectomy for Cushing’s disease

Nelson's Syndrome: A Narrative Review

Nelson's syndrome (NS) is an uncommon disease occurring as a complication of bilateral adrenalectomy (BLA) in patients with persistent Cushing's disease (CD) due to an adrenocorticotropin-producing pituitary tumor. The first reports of this syndrome were done in the 50s, although its pathophysiology is still not understood. Every year, between 1.8 and 2.6 cases are thought to occur per million people. It is characterized by hyperpigmentation, elevated adrenocorticotropic hormone (ACTH) plasma levels, and typical signs and symptoms related to pituitary adenomas, such as visual deficits due to optic pathway compression or decreased hormone production from the adenohypophysis. NS represents a challenge due to the lack of accepted diagnostic criteria and the complexity of its treatment. Moreover, the development of stereotactic radiosurgery (SRS) in the last few years has become an essential but controversial strategy for this syndrome. This review presents a comprehensive overview of NS.

Corticotroph tumor progression speed after adrenalectomy

OBJECTIVES

After bilateral adrenalectomy in Cushing's disease, corticotroph tumor progression occurs in one-third to half of patients. However, progression speed is variable, ranging from slow to rapid. The aim was to explore corticotroph progression speed, its consequences and its risk factors.

DESIGN

A retrospective single-center observational study.

METHODS

In total,103 patients with Cushing's disease who underwent bilateral adrenalectomy between 1990 and 2020 were included. Clinical, biological, histological and MRI features were collected. Median duration of follow-up after bilateral adrenalectomy was 9.31 years.

RESULTS

In total,44 patients progressed (43%). Corticotroph tumor progression speed ranged from 1 to 40.7 mm per year. Progression speed was not different before and after bilateral adrenalectomy (P = 0.29). In univariate analyses, predictive factors for rapid corticotroph tumor progression included the severity of Cushing's disease before adrenalectomy as the cause of adrenalectomy, high ACTH in the year following adrenalectomy and high Ki67 immunopositivity in the tumor. During follow-up, early morning ACTH absolute variation was associated with corticotroph tumor progression speed (P-value = 0.001). ACTH measurement after dynamic testing did not improve this association.

CONCLUSION

After adrenalectomy, corticotroph progression speed is highly variable and manageable with MRI and ACTH surveillance. Progression speed does not seem related to bilateral adrenalectomy but rather to intrinsic properties of highly proliferative and secreting tumors.

Corticotroph tumor progression after bilateral adrenalectomy: data from ERCUSYN

Corticotroph tumor progression after bilateral adrenalectomy/Nelson's syndrome (CTP-BADX/NS) is a severe complication of bilateral adrenalectomy (BADX). The aim of our study was to investigate the prevalence, presentation and outcome of CTP-BADX/NS in patients with Cushing's disease (CD) included in the European Registry on Cushing's Syndrome (ERCUSYN). We examined data on 1045 CD patients and identified 85 (8%) who underwent BADX. Of these, 73 (86%) had follow-up data available. The median duration of follow-up since BADX to the last visit/death was 7 years (IQR 2-9 years). Thirty-three patients (45%) experienced CTP-BADX/NS after 3 years (1.5-6) since BADX. Cumulative progression-free survival was 73% at 3 years, 66% at 5 years and 46% at 10 years. CTP-BADX/NS patients more frequently had a visible tumor at diagnosis of CD than patients without CTP-BADX/NS (P < 0.05). Twenty-seven CTP-BADX/NS patients underwent surgery, 48% radiotherapy and 27% received medical therapy. The median time since diagnosis of CTP-BADX/NS to the last follow-up visit was 2 years (IQR, 1-5). Control of tumor progression was not achieved in 16 of 33 (48%) patients, of whom 8 (50%) died after a mean of 4 years. Maximum adenoma size at diagnosis of CD was associated with further tumor growth in CTP-BADX/NS despite treatment (P = 0.033). Diagnosis of CTP-BADX/NS, older age, greater UFC levels at diagnosis of CD and initial treatment predicted mortality. In conclusion, CTP-BADX/NS was reported in 45% of the ERCUSYN patients who underwent BADX, and control of tumor growth was reached in half of them. Future studies are needed to establish effective strategies for prevention and treatment.

Management of Nelson’s Syndrome

Nelson’s syndrome is a potentially severe condition that may develop in patients with Cushing’s disease treated with bilateral adrenalectomy. Its management can be challenging. Pituitary surgery followed or not by radiotherapy offers the most optimal tumour control, whilst pituitary irradiation alone needs to be considered in cases requiring intervention and are poor surgical candidates. Observation is an option for patients with small lesions, not causing mass effects to vital adjacent structures but close follow-up is required for a timely detection of corticotroph tumour progression and for further treatment if required. To date, no medical therapy has been consistently proven to be effective in Nelson’s syndrome. Pharmacotherapy, however, should be considered when other management approaches have failed. A subset of patients with Nelson’s syndrome may develop further tumour growth after primary treatment, and, in some cases, a truly aggressive tumour behaviour can be demonstrated. In the absence of evidence-based guidance, the management of these cases is individualized and tailored to previously offered treatments. Temozolomide has been used in patients with aggressive Nelson’s with no consistent results. Development of tumour-targeted therapeutic agents are an unmet need for the management of aggressive cases of Nelson’s syndrome.

Prevalence of Nelson's syndrome after bilateral adrenalectomy in patients with cushing's disease: a systematic review and meta-analysis

PURPOSE

Bilateral adrenalectomy (BA) still plays an important role in the management of Cushing's disease (CD). Nelson's syndrome (NS) is a severe complication of BA, but conflicting data on its prevalence and predicting factors have been reported. The aim of this study was to determine the prevalence of NS, and identify factors associated with its development.

DATA SOURCES

Systematic literature search in four databases.

STUDY SELECTION

Observational studies reporting the prevalence of NS after BA in adult patients with CD.

DATA EXTRACTION

Data extraction and risk of bias assessment were performed by three independent investigators.

DATA SYNTHESIS

Thirty-six studies, with a total of 1316 CD patients treated with BA, were included for the primary outcome. Pooled prevalence of NS was 26% (95% CI 22-31%), with moderate to high heterogeneity (I² 67%, P < 0.01). The time from BA to NS varied from 2 months to 39 years. The prevalence of NS in the most recently published studies, where magnet resonance imaging was used, was 38% (95% CI 27-50%). The prevalence of treatment for NS was 21% (95% CI 18-26%). Relative risk for NS was not significantly affected by prior pituitary radiotherapy [0.9 (95% CI 0.5-1.6)] or pituitary surgery [0.6 (95% CI 0.4-1.0)].

CONCLUSIONS

Every fourth patient with CD treated with BA develops NS, and every fifth patient requires pituitary-specific treatment. The risk of NS may persist for up to four decades after BA. Life-long follow-up is essential for early detection and adequate treatment of NS.

Gamma knife radiosurgery in patients with Nelson's syndrome

PURPOSE

Nelson's syndrome (NS) is a long-term complication of bilateral adrenalectomy in patients with Cushing's disease. The best therapeutic strategy in NS has not been well defined. Gamma knife radiosurgery (GKRS) is very effective to stop the growth of the pituitary adenoma, which is the main goal of the treatment of patients with NS. We report the largest series of patients with NS treated by GKRS at a single center.

METHODS

The study was an observational, retrospective analysis of 28 consecutive patients with NS treated by GKRS in our department between 1995 and 2019. All patients had a growing ACTH-secreting pituitary adenoma. The main outcome of the study was to assess by the Kaplan-Meier method the risk of tumor progression after GKRS.

RESULTS

The median follow-up after GKRS treatment was 98 months (IQR 61-155 months, range 7-250 months). Two patients (7.1%) had a recurrence of disease during follow-up. The 10-year progression-free survival was 91.7% (95% CI 80.5-100%). No patient had deterioration of visual function or oculomotor function after GKRS. New onset of hypogonadism and hypothyroidism occurred in 18.8% and 14.3% of the patients at risk.

CONCLUSION

Our study confirms that GKRS may stop the tumor growth in the majority of patients with NS, even though very aggressive adenomas may ultimately escape this treatment. Safety of GKRS was good in our experience, but due attention must be paid to planning the distribution of radiation to critical structures, especially in patients previously treated by radiation.

Stereotactic radiosurgery before bilateral adrenalectomy is associated with lowered risk of Nelson's syndrome in refractory Cushing's disease patients

BACKGROUND

Nelson's syndrome is a rare but challenging sequelae of Cushing's disease (CD) after bilateral adrenalectomy (BLA). We sought to determine if stereotactic radiosurgery (SRS) of residual pituitary adenoma performed before BLA can decrease the risk of Nelson's syndrome.

METHODS

Consecutive patients with CD who underwent BLA after non-curative resection of ACTH secreting pituitary adenoma and had at least one follow-up visit after BLA were studied. Nelson's syndrome was diagnosed based on the combination of rising ACTH levels, increasing volume of the pituitary adenoma and/or hyperpigmentation.

RESULTS

Fifty patients underwent BLA for refractory CD, and 43 patients (7 men and 36 women) had at least one follow-up visit after BAL. Median endocrine, imaging, and clinical follow-up were 66 months, 69 months, and 80 months, respectively. Nine patients (22%) were diagnosed with the Nelson's syndrome at median time after BLA at 24 months (range: 0.6-119.4 months). SRS before BLA was associated with reduced risk of the Nelson's syndrome (HR = 0.126; 95%CI [0.022-0.714], p=0.019), while elevated ACTH level within 6 months after BLA was associated with increased risk for the Nelson's syndrome (HR = 9.053; 95%CI [2.076-39.472], p=0.003).

CONCLUSIONS

SRS before BLA can reduce the risk for the Nelson's syndrome in refractory CD patients requiring BLA and should be considered before proceeding to BLA. Elevated ACTH concentration within 6 months after BLA is associated with greater risk of the Nelsons' syndrome. When no prior SRS is administered, those with a high ACTH level shortly after BLA may benefit from early SRS.

Updates in the outcomes of radiation therapy for Cushing's disease

External radiation therapy (RT) directed to the pituitary gland is generally recommended in patients with Cushing's disease (CD) as adjuvant to transsphenoidal surgery, among other second-line therapies offered to patients with residual or recurrent hypercortisolism (i.e., medical treatment, repeat surgery or bilateral adrenalectomy). RT is effective for the control of tumor growth, even in invasive tumors and in Nelson's syndrome. Progress in radiation stereotactic techniques lead to improved tumor targeting and radiation delivery, thus sparing the adjacent brain structures. Stereotactic RT is associated with a 55-65% rate of cortisol normalization after several months to a few years and potentially with a lower risk of long-term complications, compared with conventional RT. Cortisol-lowering medical therapy is recommended while awaiting the radiation effects. Hypopituitarism is the most frequent side-effect, damage to optic or cranial nerves or second brain tumors are rarely reported. This review presents the updates in the efficacy and safety of the stereotactic radiation techniques in CD patients. Practical points which should be considered by the clinician before recommending RT are also presented.

Corticotroph tumor progression after bilateral adrenalectomy (Nelson's syndrome): systematic review and expert consensus recommendations

BACKGROUND

Corticotroph tumor progression (CTP) leading to Nelson's syndrome (NS) is a severe and difficult-to-treat complication subsequent to bilateral adrenalectomy (BADX) for Cushing's disease. Its characteristics are not well described, and consensus recommendations for diagnosis and treatment are missing.

METHODS

A systematic literature search was performed focusing on clinical studies and case series (≥5 patients). Definition, cumulative incidence, treatment and long-term outcomes of CTP/NS after BADX were analyzed using descriptive statistics. The results were presented and discussed at an interdisciplinary consensus workshop attended by international pituitary experts in Munich on October 28, 2018.

RESULTS

Data covered definition and cumulative incidence (34 studies, 1275 patients), surgical outcome (12 studies, 187 patients), outcome of radiation therapy (21 studies, 273 patients), and medical therapy (15 studies, 72 patients).

CONCLUSIONS

We endorse the definition of CTP-BADX/NS as radiological progression or new detection of a pituitary tumor on thin-section MRI. We recommend surveillance by MRI after 3 months and every 12 months for the first 3 years after BADX. Subsequently, we suggest clinical evaluation every 12 months and MRI at increasing intervals every 2-4 years (depending on ACTH and clinical parameters). We recommend pituitary surgery as first-line therapy in patients with CTP-BADX/NS. Surgery should be performed before extrasellar expansion of the tumor to obtain complete and long-term remission. Conventional radiotherapy or stereotactic radiosurgery should be utilized as second-line treatment for remnant tumor tissue showing extrasellar extension.

Aggressive Cushing's Disease: Molecular Pathology and Its Therapeutic Approach

Cushing's disease is a syndromic pathological condition caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (ACTHomas) mediated by hypercortisolemia. It may have a severe clinical course, including infection, psychiatric disorders, hypercoagulability, and metabolic abnormalities, despite the generally small, nonaggressive nature of the tumors. Up to 20% of ACTHomas show aggressive behavior, which is related to poor surgical outcomes, postsurgical recurrence, serious clinical course, and high mortality. Although several gene variants have been identified in both germline and somatic changes in Cushing's disease, the pathophysiology of aggressive ACTHomas is poorly understood. In this review, we focused on the aggressiveness of ACTHomas, its pathology, the current status of medical therapy, and future prospects. Crooke's cell adenoma (CCA), Nelson syndrome, and corticotroph pituitary carcinoma are representative refractory pituitary tumors that secrete superphysiological ACTH. Although clinically asymptomatic, silent corticotroph adenoma is an aggressive ACTH-producing pituitary adenoma. In this review, we summarize the current understanding of the pathophysiology of aggressive ACTHomas, including these tumors, from a molecular point of view based on genetic, pathological, and experimental evidence. The treatment of aggressive ACTHomas is clinically challenging and usually resistant to standard treatment, including surgery, radiotherapy, and established medical therapy (e.g., pasireotide and cabergoline). Temozolomide is the most prescribed pharmaceutical treatment for these tumors. Reports have shown that several treatments for patients with refractory ACTHomas include chemotherapy, such as cyclohexyl-chloroethyl-nitrosourea combined with 5-fluorouracil, or targeted therapies against several molecules including vascular endothelial growth factor receptor, cytotoxic T lymphocyte antigen 4, programmed cell death protein 1 (PD-1), and ligand for PD-1. Genetic and experimental evidence indicates that some possible therapeutic candidates are expected, such as epidermal growth factor receptor tyrosine kinase inhibitor, cyclin-dependent kinase inhibitor, and BRAF inhibitor. The development of novel treatment options for aggressive ACTHomas is an emerging task.

Rapid response of Nelson's syndrome to pasireotide in radiotherapy-naive patient

BACKGROUND

Nelson's syndrome is a well-described complication following bilateral adrenalectomy for management of Cushing's disease. There is no consensus on optimal management of Nelson's syndrome, characterized by the triad of pituitary corticotroph adenoma growth, elevated serum adrenocorticotropic hormone, and skin hyperpigmentation. Medical therapy with a variety of drug classes have been studied. One potentially promising drug already approved for Cushing's disease is pasireotide, a somatostatin analog with affinity for multiple somatostatin receptors, including subtype 5, the most highly expressed receptor on corticotroph tumors.

CASE PRESENTATION

A 24-year-old female was diagnosed with Cushing's disease with initial ACTH levels around 700-800 pg/mL. She underwent transsphenoidal surgery without remission, followed by bilateral adrenalectomy. Over the subsequent 3 years, the patient developed skin hyperpigmentation, recurrent elevations of ACTH, and tumor recurrence requiring two additional transsphenoidal surgeries. After her third transsphenoidal resection, ACTH normalized, no residual tumor was seen on radiology, and the patient's skin hyperpigmentation improved. She then had an uncomplicated full-term pregnancy, during which ACTH levels remained within normal limits. One month after delivery, ACTH levels began rising to a peak at 5,935 pg/mL. Imaging revealed two new bilateral pituitary adenomas, measuring 14 mm on the left, and 7 mm on the right. She was then started on pasireotide. After two months of therapy, ACTH decreased to 609 pg/mL, and repeat pituitary MRI showed interval decrease in size of both pituitary adenomas to 13 mm on the left and 6 mm on the right.

CONCLUSION

We report the protracted course of a young female with several recurrences of Nelson's syndrome following bilateral adrenalectomy and multiple transsphenoidal surgeries, who ultimately responded to pasireotide. Unique features of her case not described previously are the response to pasireotide in a radiotherapy-naive patient, as well as the rapid radiologic response to therapy. Her history illustrates the unresolved challenges of Nelson's syndrome and the continued need for additional studies to identify optimal management.

Recurrence after pituitary surgery in adult Cushing's disease: a systematic review on diagnosis and treatment

PURPOSE

Recurrence after pituitary surgery in Cushing's disease (CD) is a common problem ranging from 5% (minimum) to 50% (maximum) after initially successful surgery, respectively. In this review, we give an overview of the current literature regarding prevalence, diagnosis, and therapeutic options of recurrent CD.

METHODS

We systematically screened the literature regarding recurrent and persistent Cushing's disease using the MESH term Cushing's disease and recurrence. Of 717 results in PubMed, all manuscripts in English and German published between 1980 and April 2020 were screened. Case reports, comments, publications focusing on pediatric CD or CD in veterinary disciplines or studies with very small sample size (patient number < 10) were excluded. Also, papers on CD in pregnancy were not included in this review.

RESULTS AND CONCLUSIONS

Because of the high incidence of recurrence in CD, annual clinical and biochemical follow-up is paramount. 50% of recurrences occur during the first 50 months after first surgery. In case of recurrence, treatment options include second surgery, pituitary radiation, targeted medical therapy to control hypercortisolism, and bilateral adrenalectomy. Success rates of all these treatment options vary between 25 (some of the medical therapy) and 100% (bilateral adrenalectomy). All treatment options have specific advantages, limitations, and side effects. Therefore, treatment decisions have to be individualized according to the specific needs of the patient.

Nelson's Syndrome: An Update

Nelson's syndrome (NS) is a condition which may develop in patients with Cushing's disease after bilateral adrenalectomy. Although there is no formal consensus on what defines NS, corticotroph tumor growth and/or gradually increasing ACTH levels are important diagnostic elements. Pathogenesis is unclear and well-established predictive factors are lacking; high ACTH during the first year after bilateral adrenalectomy is the most consistently reported predictive parameter. Management is individualized and includes surgery, with or without radiotherapy, radiotherapy alone, and observation; medical treatments have shown inconsistent results. A subset of tumors demonstrates aggressive behavior with challenging management, malignant transformation and poor prognosis.

Outcomes of Patients with Nelson's Syndrome after Primary Treatment: A Multicenter Study from 13 UK Pituitary Centers

CONTEXT

Long-term outcomes of patients with Nelson's syndrome (NS) have been poorly explored, especially in the modern era.

OBJECTIVE

To elucidate tumor control rates, effectiveness of various treatments, and markers of prognostic relevance in patients with NS.

PATIENTS, DESIGN, AND SETTING

Retrospective cohort study of 68 patients from 13 UK pituitary centers with median imaging follow-up of 13 years (range 1-45) since NS diagnosis.

RESULTS

Management of Cushing's disease (CD) prior to NS diagnosis included surgery+adrenalectomy (n = 30; eight patients had 2 and one had 3 pituitary operations), surgery+radiotherapy+adrenalectomy (n = 17; two received >1 courses of irradiation, two had ≥2 pituitary surgeries), radiotherapy+adrenalectomy (n = 2), and adrenalectomy (n = 19). Primary management of NS mainly included surgery, radiotherapy, surgery+radiotherapy, and observation; 10-year tumor progression-free survival was 62% (surgery 80%, radiotherapy 52%, surgery+radiotherapy 81%, observation 51%). Sex, age at CD or NS diagnosis, size of adenoma (micro-/macroadenoma) at CD diagnosis, presence of pituitary tumor on imaging prior adrenalectomy, and mode of NS primary management were not predictors of tumor progression. Mode of management of CD before NS diagnosis was a significant factor predicting progression, with the group treated by surgery+radiotherapy+adrenalectomy for their CD showing the highest risk (hazard ratio 4.6; 95% confidence interval, 1.6-13.5). During follow-up, 3% of patients had malignant transformation with spinal metastases and 4% died of aggressively enlarging tumor.

CONCLUSIONS

At 10 years follow-up, 38% of the patients diagnosed with NS showed progression of their corticotroph tumor. Complexity of treatments for the CD prior to NS diagnosis, possibly reflecting corticotroph adenoma aggressiveness, predicts long-term tumor prognosis.

Cushing's syndrome - Disease monitoring: Recurrence, surveillance with biomarkers or imaging studies

Pituitary surgery is the first-line treatment for patients with Cushing's disease. For patients who are not considered candidates for pituitary surgery, pituitary radiation and bilateral adrenalectomy are further treatment alternatives. Not all patients are cured with pituitary surgery, and a substantial number of patients develop recurrence, sometimes many years after an apparently successful treatment. The same applies to patients treated with radiotherapy. Far from all patients are cured, and in many cases the disease recurs. Bilateral adrenalectomy, although always curative, causes chronic adrenal insufficiency and the remaining pituitary tumour can continue to grow and cause symptoms due to pressure on adjacent tissues, a phenomenon called Nelson's syndrome. In this paper the rate of recurrence of hypercortisolism, as well as the rate of development of Nelson's syndrome, following treatment of patients with Cushing's syndrome, will be reviewed. The aim of the paper is also to summarize clinical and biochemical factors that are associated with recurrence of hypercortisolism and how the patients should be monitored following treatment.

Long-term outcome after bilateral adrenalectomy in Cushing's disease with focus on Nelson's syndrome

OBJECTIVE

We analyzed the clinical, biochemical, and imaging findings of adrenalectomized patients with Cushing's disease (CD) in order to compare the characteristics of those who developed Nelson's syndrome (NS) versus those who did not develop this complication (NNS), aiming to identify possible predictive factors for its occurrence.

SUBJECTS AND METHODS

We performed a retrospective review of the clinical records of a group of patients with CD who underwent TBA between 1974 and 2011.

RESULTS

Out of 179 patients with CD, 13 (7.3%) underwent TBA. NS occurred in 6 of them (46%) after a mean of 24 months from the total bilateral adrenalectomy (TBA). Age at diagnosis, duration of Cushing's syndrome (CS) until TBA, and steroid replacement doses were similar in both groups. Initial urinary cortisol levels (24-hour urinary free cortisol [UFC]) were significantly higher in the NS group than in the NNS group (p = 0.009). Four patients in the NS group and three of those in the NNS group received radiotherapy before TBA (p = 0.26). Three patients in the NS group presented residual tumors before TBA, compared with none in the NNS group (p = 0.04). At 1 year after TBA, the median ACTH level was 476 ng/L (240-1500 ng/L) in the NS group and 81 ng/L (48-330 ng/L) in the NNS group (p = 0.0007).

CONCLUSION

In conclusion, a residual tumor before TBA, higher 24-hour UFC at diagnosis, and increasing ACTH levels within 1 year after TBA emerged as predictive factors of development of NS.

Characterizing and predicting the Nelson-Salassa syndrome

OBJECTIVE Nelson-Salassa syndrome (NSS) is a rare consequence of bilateral adrenalectomy (ADX) for refractory hypercortisolism due to Cushing disease (CD). Although classically defined by rapid growth of a large, invasive, adrenocorticotropin hormone (ACTH)-secreting pituitary tumor after bilateral ADX that causes cutaneous hyperpigmentation, visual disturbance, and high levels of ACTH, clinical experience suggests more variability. METHODS The authors conducted a retrospective chart review of all patients 18 years and older with a history of bilateral ADX for CD, adequate pituitary MRI, and at least 2 years of clinical follow-up. Statistical tests included Student's t-test, chi-square test, Fisher's exact test, multivariate analysis, and derived receiver operating characteristic curves. RESULTS Between 1956 and 2015, 302 patients underwent bilateral ADX for the treatment of hypercortisolism caused by CD; 88 had requisite imaging and follow-up (mean 16 years). Forty-seven patients (53%) had radiographic progression of pituitary disease and were diagnosed with NSS. Compared with patients who did not experience progression, those who developed NSS were significantly younger at the time of CD diagnosis (33 vs 44 years, p = 0.007) and at the time of bilateral ADX (35 vs 49 years, p = 0.007), had larger tumors at the time of CD diagnosis (6 mm vs 1 mm, p = 0.03), and were more likely to have undergone external-beam radiation therapy (EBRT, 43% vs 12%, p = 0.005). Among NSS patients, the mean tumor growth was 7 mm/yr (SE 6 mm/yr); the median tumor growth was 3 mm/yr. Prevalence of pathognomonic symptoms was low; the classic triad occurred in 9%, while hyperpigmentation without visual field deficit was observed in 23%, and 68% remained asymptomatic despite radiographic disease progression. NSS required treatment in 14 patients (30%). CONCLUSIONS NSS is a prevalent sequela of CD after bilateral ADX and affects more than 50% of patients. However, although radiological evidence of NSS is common, it is most often clinically indolent, with only a small minority of patients developing the more aggressive disease phenotype characterized by clinically meaningful symptoms and indications for treatment. Young age at the time of CD diagnosis or treatment with bilateral ADX, large tumor size at CD diagnosis, and EBRT are associated with progression to NSS and may be markers of aggressiveness.

STEREOTACTIC RADIATION THERAPY IN PITUITARY ADENOMAS, IS IT BETTER THAN CONVENTIONAL RADIATION THERAPY?

Pituitary radiotherapy (RT) has undergone important progress in the last decades due to the development of new stereotactic techniques which provide more precise tumour targeting with less overall radiation received by the adjacent brain structures. Pituitary surgery is usually first-line therapy in most patients with nonfunctioning (NFPA) and functioning adenomas (except for prolactinomas and large growth hormone (GH) secreting adenomas), while RT is used as second or third-line therapy. The benefits of RT (tumour volume control and, in functional tumours, decreased hormonal secretion) are hampered by the long latency of the effect and the potential side effects. This review presents the updates in the efficacy and safety of the new stereotactic radiation techniques in patients with NFPA, GH-, ACTH- or PRL-secreting pituitary adenomas.

Methods

A systematic review was performed using PubMed and articles/abstracts and reviews detailing RT in pituitary adenomas from 2000 to 2017 were included.

Results

Stereotactic radiosurgery (SRS) and fractionated stereotactic RT (FSRT) provide high rates of tumour control i.e. stable or decrease in tumour size, in all types of pituitary adenomas (median 92 - 98%) at 5 years. Endocrinological remission is however significantly lower: 44-52% in acromegaly, 54-64% in Cushing's disease and around 30% in prolactinomas at 5 years. The rate of new hypopituitarism varies from 10% to 50% at 5 years in all tumour types and as expected increases with the duration of follow-up (FU). The risk for other radiation-induced complications is usually low (0-5% for new visual deficits, cranial nerves damage or brain radionecrosis and extremely low for secondary brain tumours), however longer FU is needed to determine rates of secondary tumours. Notably, in acromegaly, there may be a higher risk for stroke with FSRT.

Conclusion

Stereotactic radiotherapy can be an effective treatment option for patients with persistent or recurrent pituitary adenomas after unsuccessful surgery (especially if residual tumour is enlarging) and/or resistance or unavailability of medical therapy. Comparison with conventional radiation therapy (CRT) is rather difficult, due to the substantial heterogeneity of the studies. In order to evaluate the potential brain-sparing effect of the new stereotactic techniques, suggested by the current data, long-term studies evaluating secondary morbidity and mortality are needed.

The risks of overlooking the diagnosis of secreting pituitary adenomas

Secreting pituitary adenomas that cause acromegaly and Cushing’s disease, as well as prolactinomas and thyrotroph adenomas, are uncommon, usually benign, slow-growing tumours. The rarity of these conditions means that their diagnosis is not familiar to most non-specialist physicians. Consequently, pituitary adenomas may be overlooked and remain untreated, and affected individuals may develop serious comorbidities that reduce their quality of life and life expectancy. Because many signs and symptoms of pituitary adenomas overlap with those of other, more common disorders, general practitioners and non-endocrinology specialists need to be aware of the “red flags” suggestive of these conditions. A long duration of active disease in patients with secreting pituitary adenomas is associated with an increased risk of comorbidities and reduced quality of life. Appropriate treatment can lead to disease remission, and, although some symptoms may persist in some patients, treatment usually reduces the incidence and severity of comorbidities and improves quality of life. Therefore, correct, early diagnosis and characterization of a pituitary adenoma is crucial for patients, to trigger timely, appropriate treatment and to optimize outcome. This article provides an overview of the epidemiology of hormonal syndromes associated with pituitary adenomas, discusses the difficulties of and considerations for their diagnosis, and reviews the comorbidities that may develop, but can be prevented, by accurate diagnosis and appropriate treatment. We hope this review will help general practitioners and non-endocrinology specialists to suspect secreting pituitary adenomas and refer patients to an endocrinologist for confirmation of the diagnosis and treatment.

Surgical management of adrenocorticotropic hormone-secreting pituitary adenomas

Cushing's disease is defined as hypercortisolemia caused by secretion of adrenocorticotropic hormone from a pituitary adenoma. The diagnosis of Cushing's disease is based on clinical symptoms, laboratory and imaging findings. Once an adrenocorticotropic-hormone-secreting adenoma is found, the standard of care is transsphenoidal adenomectomy. MRI negative microadenomas and large, invasive macroadenomas provide a surgical and clinical challenge and are best handled at high volume centers. Multiple options exist for refractory disease or recurrence, including repeat surgery, radiosurgery and radiotherapy, medical management and bilateral adrenalectomy.

Bilateral adrenalectomy for Cushing's syndrome: Pros and cons

AIM

To assess the outcome of patients undergoing bilateral adrenalectomy for Cushing's syndrome (CS).

METHODS

All patients who underwent bilateral adrenalectomy for CS at the Department of Endocrine Surgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences hospital between 1991 and 2013 were included. Medical records were reviewed to obtain patient characteristics and follow-up data.

RESULTS

Twenty-seven patients were studied. Mean age was 28.74 ± 12.95 years (range 9-60), male:female ratio was 1.7:1. About half that is, 48.19% were of Cushing's disease (failed trans-sphenoidal surgery [TSS]), 37.04% were of ectopic CS (ECS), and 14.81% were of CS due to bilateral adrenal pathology. Median follow-up period was 80.5 months. Before surgery, 74.1% patients had body mass index > which after surgery declined to <25 in 75% of them. Hypertension was present in 85.2% and after surgery resolved in 40%. Diabetes mellitus was present in 44.4% and after surgery resolved in 33% of them. Hirsutism and proximal muscle weakness were present in 55.6% and 70.4% patients, respectively, and after surgery improved markedly in all patients. Adrenal crisis developed in 36.3% and Nelson's syndrome in 41.7% patients during follow-up. Three patients died in perioperative period while three succumbed to the disease during follow-up. Two patients developed recurrence of endogenous cortisol production during the follow-up period.

CONCLUSIONS

Bilateral adrenalectomy is a valid treatment option for palliating severe symptoms in Pituitary Cushing's with failed TSS and unlocalized ECS but the procedure is curative for CS due to bilateral adrenal disease. Overall morbidity and mortality is higher than other endocrine operations. Co-morbidities tend to be more severe and are a risk factor for mortality during the time patient survives.

Nelson's syndrome: a review of the clinical manifestations, pathophysiology, and treatment strategies

Nelson's syndrome is a rare clinical manifestation that occurs in 8%-47% of patients as a complication of bilateral adrenalectomy, a procedure that is used to control hypercortisolism in patients with Cushing's disease. First described in 1958 by Dr. Don Nelson, the disease has since become associated with a clinical triad of hyperpigmentation, excessive adrenocorticotropin secretion, and a corticotroph adenoma. Even so, for the past several years the diagnostic criteria and management of Nelson's syndrome have been inadequately studied. The primary treatment for Nelson's syndrome is transsphenoidal surgery. Other stand-alone therapies, which in many cases have been used as adjuvant treatments with surgery, include radiotherapy, radiosurgery, and pharmacotherapy. Prophylactic radiotherapy at the time of bilateral adrenalectomy can prevent Nelson's syndrome (protective effect). The most promising pharmacological agents are temozolomide, octreotide, and pasireotide, but these agents are often administered after transsphenoidal surgery. In murine models, rosiglitazone has shown some efficacy, but these results have not yet been found in human studies. In this article, the authors review the clinical manifestations, pathophysiology, diagnostic criteria, and efficacy of multimodal treatment strategies for Nelson's syndrome.

The role of bilateral adrenalectomy in the treatment of refractory Cushing's disease

Cushing's syndrome (CS) results from sustained exposure to excessive levels of free glucocorticoids. One of the main causes of CS is excessive adrenocorticotropic hormone (ACTH) secretion by tumors in the pituitary gland (Cushing's disease [CD]). Cushing's disease and its associated hypercortisolism have a breadth of debilitating symptoms associated with an increased mortality rate, warranting urgent treatment. Currently, the first line of treatment for CD is transsphenoidal surgery (TSS), with excellent long-term results. Transsphenoidal resections performed by experienced surgeons have shown remission rates ranging from 70% to 90%. However, some patients do not achieve normalization of their hypercortisolemic state after TSS and continue to have persistent or recurrent CD. For these patients, various therapeutic options after failed TSS include repeat TSS, radiotherapy, medical therapy, and bilateral adrenalectomy (BLA). Bilateral adrenalectomy has been shown to be a safe and effective treatment modality for persistent or recurrent CD with an immediate and definitive cure of the hypercortisolemic state. BLA was traditionally performed through an open approach, but since the advent of laparoscopic adrenalectomy, the laparoscopic approach has become the surgical method of choice. Advances in technology, refinement in surgical skills, competency in adrenopathology, and emphasis on multidisciplinary collaborations have greatly reduced morbidity and mortality associated with adrenalectomy surgery in a high-risk patient population. In this article, the authors review the role of BLA in the treatment of refractory CD. The clinical indications, current surgical and endocrinological results reported in the literature, surgical technique (open vs laparoscopic), drawbacks, and complications of BLA are discussed.

Re-examining Nelson's syndrome

PURPOSE OF REVIEW

Nelson's syndrome is a rare complication that can occur during the course of management of Cushing's disease. This article summarizes the recent literature on the diagnosis, monitoring and treatment of this potentially life-threatening outcome.

RECENT FINDINGS

Nelson's syndrome, with rising adrenocorticotropin hormone levels and corticotroph tumor progression on diagnostic imaging, can develop following treatment of refractory Cushing's disease with total bilateral adrenalectomy with/without radiotherapy. However, data showing that radiotherapy prevents Nelson's syndrome is inconsistent. In addition to the treatment of Nelson's syndrome with neurosurgery with/without adjuvant radiotherapy, selective somatostatin analogs and dopamine agonists, as well as other novel agents, have been used with increasing frequency in treating cases of Nelson's syndrome with limited benefit. The risk-benefit profile of each of these therapies is still not completely understood.

SUMMARY

Consensus guidelines on the evaluation and management of Nelson's syndrome are lacking. This article highlights areas in the surveillance of Cushing's disease patients, and diagnostic criteria and treatment regimens for Nelson's syndrome that require further research and review by experts in the field.

The Treatment of Cushing's Disease

Cushing's disease (CD), or pituitary-dependent Cushing's syndrome, is a severe endocrine disease caused by a corticotroph pituitary tumor and associated with increased morbidity and mortality. The first-line treatment for CD is pituitary surgery, which is followed by disease remission in around 78% and relapse in around 13% of patients during the 10-year period after surgery, so that nearly one third of patients experience in the long-term a failure of surgery and require an additional second-line treatment. Patients with persistent or recurrent CD require additional treatments, including pituitary radiotherapy, adrenal surgery, and/or medical therapy. Pituitary radiotherapy is effective in controlling cortisol excess in a large percentage of patients, but it is associated with a considerable risk of hypopituitarism. Adrenal surgery is followed by a rapid and definitive control of cortisol excess in nearly all patients, but it induces adrenal insufficiency. Medical therapy has recently acquired a more important role compared to the past, due to the recent employment of novel compounds able to control cortisol secretion or action. Currently, medical therapy is used as a presurgical treatment, particularly for severe disease; or as postsurgical treatment, in cases of failure or incomplete surgical tumor resection; or as bridging therapy before, during, and after radiotherapy while waiting for disease control; or, in selected cases, as primary therapy, mainly when surgery is not an option. The adrenal-directed drug ketoconazole is the most commonly used drug, mainly because of its rapid action, whereas the glucocorticoid receptor antagonist, mifepristone, is highly effective in controlling clinical comorbidities, mainly glucose intolerance, thus being a useful treatment for CD when it is associated with diabetes mellitus. Pituitary-directed drugs have the advantage of acting at the site responsible for CD, the pituitary tumor. Among this group of drugs, the dopamine agonist cabergoline and the somatostatin analog pasireotide result in disease remission in a consistent subgroup of patients with CD. Recently, pasireotide has been approved for the treatment of CD when surgery has failed or when surgery is not an option, and mifepristone has been approved for the treatment of Cushing's syndrome when associated with impairment of glucose metabolism in case of the lack of a surgical indication. Recent experience suggests that the combination of different drugs may be able to control cortisol excess in a great majority of patients with CD.

Bilateral adrenalectomy for Cushing's disease

PURPOSE

Review the indications, outcomes, and consequences of bilateral adrenalectomy (BLA) in patients with Cushing's disease.

METHODS

A literature review was performed.

RESULTS

The primary therapy for Cushing's disease is surgery, with medical therapy and radiation therapy relegated to an adjuvant role. BLA is indicated in cases of persistent disease following pituitary surgery or in situations where rapid normalization of hypercortisolism is required. When performed via the laparoscopic approach, BLA is associated with a significantly reduced morbidity compared to the traditional, open approach. Following BLA, patients are at risk for adrenal crisis and the concern of Nelson's syndrome. However, BLA leads to a rapid resolution of the signs and symptoms of CS and leads to an improved long-term quality of life.

CONCLUSION

BLA should be considered in the treatment algorithm for patients with persistent CD after failed pituitary surgery, especially in patients who have severe consequences of hypercortisolism or desire pregnancy.

Effect of stereotactic radiosurgery before bilateral adrenalectomy for Cushing's disease on the incidence of Nelson's syndrome

Object

Nelson's syndrome (NS) is a significant and frequent risk for patients with Cushing's disease (CD) who undergo bilateral adrenalectomy. A recent study has shown tumor progression in 47% of patients at risk for NS. The authors sought to define the rate of NS in patients who were treated with Gamma Knife stereotactic radiosurgery (GK SRS) prior to bilateral adrenalectomy.

Methods

Consecutive patients with CD who were treated with GK SRS after pituitary surgery but before bilateral adrenalectomy were included. Serial MRI sequences were analyzed to evaluate for pituitary tumor growth. Clinical evaluations were performed to screen for NS. Follow-up for adrenocorticotropic hormone levels and hormone studies of other pituitary axes was performed.

Results

Twenty consecutive patients were followed with neuroimaging and clinically for a median of 5.4 years (range 0.6–12 years). One patient (5%) developed pituitary tumor growth consistent with NS 9 months after adrenalectomy. By Kaplan-Meier analysis, progression-free survival was 94.7% at 1, 3, and 7 years. No predisposing factors were identified for the tumor progression. Two patients developed new pituitary dysfunction and no patient developed cranial neuropathy or visual deficit after GK SRS.

Conclusions

These findings suggest that GK SRS not only serves a role as second-line therapy for CD, but that it also provides prophylaxis for NS when used before bilateral adrenalectomy.

Nelson's syndrome presenting as bilateral oculomotor palsy

Nelson's syndrome refers to a clinical spectrum arising from progressive enlargement of pituitary adenoma and elevated adrenocorticotrophic hormone after total bilateral adrenalectomy for Cushing's disease comprising of hyperpigmentation, visual field defects which can be life threatening. We report here a 50-year male presenting with rapid onset of Nelson's syndrome with an unusual finding of bilateral oculomotor palsy mistakenly treated as ocular myasthenia.

Diagnosis and Multimodality Management of Cushing's Disease: A Practical Review

Cushing's Disease is caused by oversecretion of ACTH from a pituitary adenoma and results in subsequent elevations of systemic cortisol, ultimately contributing to reduced patient survival. The diagnosis of Cushing's Disease frequently involves a stepwise approach including clinical, laboratory, neuroimaging, and sometimes interventional radiology techniques, often mandating multidisciplinary collaboration from numerous specialty practitioners. Pituitary microadenomas that do not appear on designated pituitary MRI or dynamic contrast protocols may pose a particularly challenging subset of this disease. The treatment of Cushing's Disease typically involves transsphenoidal surgical resection of the pituitary adenoma as a first-line option, yet may require the addition of adjunctive measures such as stereotactic radiosurgery or medical management to achieve normalization of serum cortisol levels. Vigilant long-term serial endocrine monitoring of patients is imperative in order to detect any recurrence that may occur, even years following initial remission. In this paper, a stepwise approach to the diagnosis, and various management strategies and associated outcomes in patients with Cushing's Disease are discussed.

Cushing's surgery: Role of the anesthesiologist

Cushing's syndrome is a clinical situation, caused by excessive glucocorticoid level, resulting in several features such as central obesity, supraclavicular fat, "moon face," "buffalo hump," hyperglycemia, metabolic alkalosis, hypokalemia, poor wound healing, easy bruising, hypertension, proximal muscle weakness, thin extremities, skin thinning, menstrual irregularities, and purple striae. In the perioperative period, the anesthesiologist must deal with difficult ventilation and intubation, hemodynamic disturbances, volume overload and hypokalemia, glucose intolerance, and diabetes, maintaining the blood cortisol level and preventing the glucocorticoid deficiency. This syndrome is quite rare and its features make these patients very difficult to the anesthesiologist.

Nelson's syndrome

Nelson's syndrome is a potentially life-threatening condition that does not infrequently develop following total bilateral adrenalectomy (TBA) for the treatment of Cushing's disease. In this review article, we discuss some controversial aspects of Nelson's syndrome including diagnosis, predictive factors, aetiology, pathology and management based on data from the existing literature and the experience of our own tertiary centre. Definitive diagnostic criteria for Nelson's syndrome are lacking. We argue in favour of a new set of criteria. We propose that Nelson's syndrome should be diagnosed in any patient with prior TBA for the treatment of Cushing's disease and with at least one of the following criteria: i) an expanding pituitary mass lesion compared with pre-TBA images; ii) an elevated 0800 h plasma level of ACTH (>500 ng/l) in addition to progressive elevations of ACTH (a rise of >30%) on at least three consecutive occasions. Regarding predictive factors for the development of Nelson's syndrome post TBA, current evidence favours the presence of residual pituitary tumour on magnetic resonance imaging (MRI) post transsphenoidal surgery (TSS); an aggressive subtype of corticotrophinoma (based on MRI growth rapidity and histology of TSS samples); lack of prophylactic neoadjuvant pituitary radiotherapy at the time of TBA and a rapid rise of ACTH levels in year 1 post TBA. Finally, more studies are needed to assess the efficacy of therapeutic strategies in Nelson's syndrome, including the alkylating agent, temozolomide, which holds promise as a novel and effective therapeutic agent in the treatment of associated aggressive corticotroph tumours. It is timely to review these controversies and to suggest guidelines for future audit.

[Adrenal adenoma as a cause of Cushing's syndrome: twenty years' experience in a referral center in Mexico]

INTRODUCTION

Cushing's syndrome (CS) includes a wide range of clinical and laboratory abnormalities and is the final outcome of chronic glucocorticoid exposure. Adrenal adenomas are an uncommon cause of adult CS.

OBJECTIVE

To describe the characteristics and outcome of patients with CS caused by adrenal adenomas in a referral center.

METHODS

We performed a retrospective cross-sectional observational study of patients with a diagnosis of CS caused by adrenal adenomas managed in our center over a 20-year period. Our clinical experience in the diagnosis and treatment of this entity was analyzed.

RESULTS

There were a total of 20 patients, 19 women and one man. The mean age was 25.9 years (14 to 52). The most frequently recorded clinical data were hirsutism and moon face. The mean morning cortisol level was 26.9±10.7 mcg/dl, the mean afternoon level was 24.4±8.5 mcg/dl and the mean corticotropin (ACTH) concentration was 24±19.4 pg/ml. Only four patients (20%) had ACTH levels below 5 pg/ml. The results of dynamic testing with dexamethasone suggested adrenal adenoma in 100% of the patients. Seventy percent of adenomas were found in the left gland. The mean size of the lesion was 2.8±0.47 cm.

CONCLUSIONS

In dynamic testing, the criteria of non-suppression with high doses of dexamethasone were evident in almost all patients. ACTH measurement in our center was not reliable in identifying adrenal adenoma as a cause of CS.

Nelson's syndrome: physiopathology, management and prognosis

A classical description of a postadrenalectomy syndrome in Cushing's disease, described in 1958 by Don Nelson, included a deep skin hyperpigmentation, presence of a large pituitary tumor, high plasma adrenocorticotropic hormone levels and visual field deficits. The main pathophysiological mechanism of Nelson's syndrome development is a loss of feedback control of hypercortisolemia on corticotroph as a consequence of the removal of hyperactive adrenal glands. Modern techniques of imaging, computed tomography and MRI, made early detection of pituitary tumor at the stage of microadenoma possible. Determinations of plasma adrenocorticotropic hormone concentration during replacement therapy are the next essential diagnostic element. Absolute temporal scotomas in visual field examination are an early sign of Nelson's syndrome. Sufficient hydrocortisone therapy is very important to avoid hypocortisolemia, which stimulates corticotroph cells. Methods of treatment include neurosurgery, radiation therapy and pharmacotherapy. Prognosis in Nelson's syndrome depends on the stage of the disease; it may be poor in invasive pituitary tumors.

Trilostane-induced inhibition of cortisol secretion results in reduced negative feedback at the hypothalamic-pituitary axis

Cushing's disease caused by pituitary corticotroph adenoma in dogs is usually treated by medical treatment, and the efficacy of this treatment has been reported. However, controversy remains as to whether reduced negative feedback through the inhibition of cortisol secretion, similar to Nelson's syndrome, may appear as an adverse effect. The purpose of this study was to investigate the effect of reduced negative feedback through the inhibition of cortisol secretion by daily trilostane administration on the pituitary-adrenal axis in clinically normal dogs. Dogs were administered 5mg/kg trilostane twice a day every day for 8 weeks (n=8) or 16 weeks (n=3). After the initiation of trilostane administration, plasma adrenocorticotropic hormone (ACTH) concentrations were increased remarkably. As assessed by magnetic resonance imaging (MRI) during administration, the pituitary became enlarged. After trilostane administration, the cytoplasmic areas of the pituitary corticotrophs were increased and the ratio of pituitary corticotrophs to all cells in the anterior lobe was greater in the trilostane-treated dogs than that in untreated animals. In addition, histological examinations revealed bilateral adrenal cortical hyperplasia. Using real-time PCR quantification, the expression of proopiomelanocortin (POMC) mRNA in the pituitary and ACTH receptor (ACTH-R) mRNA in the adrenal gland was greater in the dogs treated with trilostane than in untreated dogs. These results indicate that reduced negative feedback induced hyperfunction of the pituitary corticotrophs and pituitary enlargement in healthy dogs. These changes suggest that the inhibition of cortisol secretion by trilostane may increase the risk for accelerating the growth of corticotroph adenomas in dogs with Cushing's disease.

Surgery for Cushing's syndrome: an historical review and recent ten-year experience

BACKGROUND

Cushing's syndrome (CS), due to multiple etiologies, is a disorder associated with the ravages of cortisol excess. The purpose of this review article is to provide a historical synopsis of surgery for CS, review a recent 10-year period of operative management at a tertiary care facility, and to outline a practical approach to diagnosis and management.

MATERIALS AND METHODS

From 1996 to 2005, 298 patients underwent 322 operative procedures for CS at Mayo Clinic, Rochester, Minnesota. A retrospective chart review was carried out. Data was gathered regarding demographics, preoperative assessment, procedures performed, and outcomes. Data are presented as counts and percentages. Five-year survival rates were calculated where applicable by the Kaplan-Meier method. Statistical analysis was carried out with SAS, version 9 (SAS Institute, Inc., Cary, NC).

RESULTS

Two-hundred thirty-one patients (78%) had ACTH-dependent CS and 67 patients (22%) had ACTH-independent CS. One-hundred ninety-six patients (66%) had pituitary-dependent CS and 35 patients (12%) had ectopic ACTH syndrome. Fifty-four patients (18%) had cortisol-secreting adenomas, 10 patients (3%) had cortisol-producing adrenocortical carcinomas, and 1% had other causes. Cure rates for first time pituitary operations (transsphenoidal, sublabial, and endonasal) were 80% and 55% for reoperations. Most benign adrenal processes could be managed laparoscopically. Five-year survival rates (all causes) were 90%, 51%, and 23% for adrenocortical adenomas, ectopic ACTH syndrome, and adrenocortical carcinomas, respectively.

CONCLUSIONS

Surgery for CS is highly successful for pituitary-dependent CS and most ACTH-independent adrenal causes. Bilateral total adrenalectomy can also provide effective palliation from the ravages of hypercortisolism in patients with ectopic ACTH syndrome and for those who have failed transsphenoidal surgery. Unfortunately, to date, adrenocortical carcinomas are rarely cured. Future successes with this disease will likely depend on a better understanding of tumor biology, more effective adjuvant therapies and earlier detection. Clearly, IPSS, advances in cross-sectional imaging, along with developments in transsphenoidal and laparoscopic surgery, have had the greatest impact on today's management of the complex patient with CS.

Nelson syndrome: comprehensive review of pathophysiology, diagnosis, and management

Nelson syndrome (NS) is a rare clinical manifestation of an enlarging pituitary adenoma that can occur following bilateral adrenal gland removal performed for the treatment of Cushing disease. It is characterized by excess adreno-corticotropin secretion and hyperpigmentation of the skin and mucus membranes. The authors present a comprehensive review of the pathophysiology, diagnosis, and management of NS. Corticotroph adenomas in NS remain challenging tumors that can lead to significant rates of morbidity and mortality. A better understanding of the natural history of NS, advances in neurophysiology and neuroimaging, and growing experience with surgical intervention and radiation have expanded the repertoire of treatments. Currently available treatments include surgical, radiation, and medical therapy. Although the primary treatment for each tumor type may vary, it is important to consider all of the available options and select the one that is most appropriate for the individual case, particularly in cases of lesions resistant to intervention.

Radiotherapy and radiosurgery for Cushing's disease

Patients with residual or recurrent Cushing's disease receive external beam radiotherapy (RT) with the aim of achieving long-term tumour control and normalization of elevated hormone levels. Treatment is given either as conventional radiotherapy using conformal techniques or as stereotactic radiotherapy, which is either used as fractionated treatment (SCRT) or as single fraction radiosurgery (SRS). We describe the technical aspects of treatment and report a systematic review of the published literature on the efficacy and toxicity of conventional RT, SCRT and SRS. There are no studies directly comparing the different radiation techniques and the reported results are inevitably of selected patients by investigators with interest in the treatment tested. Nevertheless the review of the published literature suggests better hormone and tumour control rates after fractionated irradiation compared to single fraction radiosurgery. Hypopituitarism represents the most commonly reported late complication of radiotherapy seen after all treatments. Although the incidence of other late effects is low, the risk of radiation injury to normal neural structures is higher with single fraction compared to fractionated treatment. Stereotactic techniques offer more localized irradiation compared with conventional radiotherapy, however longer follow-up is necessary to confirm the potential reduction of long-term radiation toxicity of fractionated SCRT compared to conventional RT. On the basis of the available literature, fractionated conventional and stereotactic radiotherapy offer effective treatment for Cushing's disease not controlled with surgery alone. The lower efficacy and higher toxicity of single fraction treatment suggest that SRS is not the appropriate therapy for the majority of patients with Cushing's disease.

Nelson syndrome: historical perspectives and current concepts

✓The appearance of an adrenocorticotropic hormone (ACTH)–producing tumor after bilateral adrenalectomy for Cushing disease was first described by Nelson in 1958. The syndrome that now bears his name was characterized by hyperpigmentation, a sellar mass, and increased plasma ACTH levels. The treatment of Cushing disease has changed drastically since the 1950s, when the choice was adrenalectomy. Thus, the occurrence, diagnosis, and treatment of Nelson syndrome have changed as well. In the modern era of high-resolution neuroimaging, transsphenoidal microneu-rosurgery, and stereotactic radiosurgery, Nelson syndrome has become a rare entity. The authors describe the history of the diagnosis and treatment of Nelson syndrome. In light of the changes described, the authors believe this disease must be reevaluated in the contemporary era and a modern paradigm adopted.