Cushing's syndrome due to an ectopic ACTH-secreting pituitary tumour mimicking occult paraneoplastic ectopic ACTH production

Clinical and radiological presentation of parasellar ectopic pituitary adenomas: case series and systematic review of the literature

PURPOSE

Parasellar ectopic pituitary adenomas (pEPAs) are extremely rare tumors located out of the sella turcica. PEPAs are heterogeneous entities in terms of anatomical localization and secretion of anterior pituitary hormones.

METHODS

Multicenter retrospective study. Clinical charts' consultation of patients diagnosed with parasellar lesions, to identify all subjects fulfilling the diagnostic criteria of parasellar EPAs. Systematic review of the literature focused on the medical management of prolactin-secreting pEPAs and on the prevalence of radiological bone invasion in pEPAs.

RESULTS

We identified four cases of pEPAs: (1) 54-year-old female with a prolactin-secreting suprasellar EPA successfully treated with cabergoline; (2) 74-year-old male with a non-functioning EPA of the sphenoidal sinus treated with endoscopic transsphenoidal surgery; (3) 75-year-old female with a giant lesion of the skull base (maximum diameter 7.2 cm) diagnosed as a non-functioning EPA after biopsy; (4) 49-year-old male with a silent corticotroph EPA of the sphenoidal sinus and clivus. Three out of four cases had radiological evidence of invasion of the surrounding bone structures. A systematic review of the literature highlighted that medical therapy can be effective in prolactin-secreting pEPAs. Overall, we found mention of local invasiveness in 65/147 cases (44.2%), confirmed by radiological signs of bone invasion/erosion.

CONCLUSION

Our experience confirms the heterogeneity of pEPAs in terms of clinical and radiological presentation, as well as hormone secretion. PEPAs show a high frequency of radiological bone invasion, though similar to that of sellar pituitary adenomas. Although extremely rare, pEPAs need to be considered in the differential diagnosis of parasellar lesions.

Ectopic pituitary adenomas: clinical features, diagnostic challenges and management

PURPOSE

Ectopic pituitary adenomas (EPAs) are extremely rare pituitary adenomas located outside the sella turcica without any connection with intrasellar components. This study aims to review all the reported cases to date and describe the clinical characteristics of EPAs.

METHODS

In a retrospective chart review, 14 patients were identified with EPAs in our hospital. A literature review was performed, and 166 cases in the literature met the criteria. Clinical data were analyzed.

RESULTS

Of 180 patients with EPAs, the mean age at diagnosis was 45.4 years, and 66.5% of the patients were females. EPAs were mainly located in the sphenoid sinus (34.4%) and suprasellar region (25.6%), followed by the clivus (15.6%), cavernous sinus (13.3%) and nasopharynx (5.6%). Adrenocorticotropic hormone (ACTH)-secreting (38.9%) and nonfunctioning (27.2%) adenomas were predominant. Patients with suprasellar EPAs were more likely to present menstrual disorders and visual changes, while patients with clival EPAs were more likely to suffer from headaches. EPAs in the cavernous sinus and suprasellar space were more likely to be initially misdiagnosed as a suspicious intrasellar mass on imaging examination. The complete tumor resection rates for EPAs in the sphenoid sinus, suprasellar region, clivus, cavernous sinus and nasopharynx were 72.3%, 88.6%, 45.0%, 73.3% and 88.9%, respectively.

CONCLUSIONS

EPA clinical characteristics varied across different tumor locations and hormone-secreting types. In addition to comprehensive hormone evaluation and careful review of imaging data, nuclear medicine and surgical biopsy should also be considered when facing differential difficulty. EPA management should be individualized.

Long-term follow-up for ectopic ACTH-secreting pituitary adenoma in a single tertiary medical center and a literature review

BACKGROUND

Ectopic ACTH-secreting pituitary adenoma (EAPA) are a rare cause of Cushing's disease. Due to the lack of consensus and experience in terms of the diagnosis and treatment of EAPAs, preoperative identification and optimal treatment remain challenging.

PURPOSE

To investigate the characteristics of EAPAs and offer some proposals for the diagnosis and management of this uncommon disease, the EAPA patients admitted to our center and all of the EAPA cases reported in the literature were reviewed.

METHODS

In a retrospective electronic medical chart review, 6 patients (0.39%) with EAPAs were identified from 1536 consecutive patients who were admitted to our hospital with a diagnosis of Cushing's syndrome between January 2000 and August 2019. A literature review was performed on the online databases PubMed and EMBASE, and 52 cases conformed to the criteria. The data regarding biochemical tests, imaging examinations and follow-ups were analyzed.

RESULTS

The mean age of patients with EAPAs was 37.7 years old, and an obvious female predominance (3.5: 1) was demonstrated. The most common location of EAPAs was the cavernous sinus (34.5%), followed by the sphenoid sinus (31.0%) and the suprasellar region (20.7%). No significant differences in the biochemical test results were found among tumors in different locations. Except for sex, no risk factors related to remission were found. Although no significant differences among different locations were found, the tumors in the cavernous sinus had a relatively higher rate of invisibility in terms of imaging and a higher non-remission rate than tumors in other locations.

CONCLUSIONS

In patients with negative intrasellar findings, the uncommon disease of EAPA should be considered. Due to the endocrine similarity between intrasellar pituitary corticotrophin adenoma and EAPA, the preoperative identification of EAPA depends on a careful review of the imaging examinations. Locations such as the cavernous sinus, sphenoid sinus and suprasellar region should be considered first. Tumor resection is recommended when the diagnosis is confirmed.

Variability in Clinical Presentation and Pathologic Implications of Ectopic Pituitary Tumors: Critical Review of Literature

OBJECTIVE

Pituitary tumors are common, well-described skull base tumors of sellar origin. However, there are reports of rare ectopic pituitary tumors that are found exclusively outside of the sella turcica. Ectopic pituitary tumors have not been holistically analyzed. This study describes presentation and clinical patterns found among patients with ectopic pituitary tumors.

METHODS

A comprehensive review of the literature was performed for clinical descriptions of ectopic pituitary tumors. Reports of 85 applicable cases were evaluated.

RESULTS

The most common locations of ectopic pituitary tumors were the sphenoid sinus, clivus, suprasellar space, nasopharynx, and cavernous sinus. The majority of ectopic pituitary tumors were reported as being functional secretory tumors; they were statistically significantly more likely to be functional tumors than sellar pituitary tumors. Adrenocorticotrophic hormone, prolactin, growth hormone, and thyroid-stimulating hormone-secreting tumors were most commonly found. Bone invasion was reported in more than one third of the cases, and malignant transformations were reported in 6 cases. A large majority of patients presented with hormonal, neurologic, or physiologic symptoms.

CONCLUSIONS

Ectopic pituitary tumors are a rare entity of pituitary tumors with a presentation that can mimic those of other skull base tumors. Clinical presentation often correlates to location of the tumor. Ectopic pituitary tumors were significantly more likely to be functional secretory tumors. They may also exhibit more aggressive behavior than sellar-located tumors. Ectopic pituitary tumors may be part of a spectrum of presenting pathologies. Further genetic or genomic analysis is necessary to better understand their pathogenesis and clinical presentations.

Ectopic ACTH-secreting pituitary adenoma of the sphenoid sinus: case report of endoscopic endonasal resection and systematic review of the literature

Ectopic pituitary adenomas are exceedingly rare entities that are often misdiagnosed. The resulting delay in diagnosis may be particularly concerning in the case of Cushing syndrome caused by an ectopic adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma. Although the total resection of ectopic adenomas results in rapid and durable remission, persistent Cushing syndrome is often associated with permanently damaging invasive procedures and significantly higher risk of mortality. The authors report the case of a 48-year-old man with ACTH-dependent Cushing syndrome. On the morning before surgery, his serum cortisol measured 51 μg/dl, his ACTH level was 195.7 pg/ml, and his urinary free cortisol level was 2109 μg/day. Serum cortisol was not suppressed with the administration of high-dose dexamethasone. Imaging showed separate masses in both the sphenoid sinus and the pituitary gland, complicating the diagnostic process and requiring pathological assessment of both masses. No other abnormalities were found on thoracic, abdominal, or pelvic scans. Gross-total resection of both lesions was accomplished via an endoscopic endonasal transsphenoidal approach. Pathology confirmed an ectopic ACTH pituitary adenoma of the sphenoid sinus and a Crooke hyaline change of the pituitary gland. The patient achieved stable hormonal remission without significant postoperative complications, returned to full activity within 3 months, and remained disease free nearly 1 year after tumor resection. In a systematic literature review, the authors identified 41 cases of ectopic ACTH-secreting pituitary adenomas, including 18 arising in the sphenoid sinus without direct involvement of the sella. Including the case described here, the total number of ectopic ACTH pituitary adenomas arising in the sphenoid sinus was 19, and the total number of ectopic ACTH pituitary adenomas without regard to location was 42. For the 19 patients with adenomas found in the sphenoid sinus, ages ranged from 16 to 76 years, and there were 15 women and 4 men. The mean and median diameters of the resected sphenoid masses were 13.9 and 8 mm, respectively, with a range of 3-55 mm. Seven were microadenomas (< 1 cm). Fifteen of the 19 cases reported serum ACTH and morning cortisol levels, the means of which were 106.7 pg/ml and 32.5 μg/dl, respectively. Gross-total tumor resection was achieved in all patients except one, and in all of them durable hormonal remission of Cushing syndrome was achieved (mean follow-up time 20 months). Ectopic pituitary adenomas are rare but important causes of Cushing syndrome and related endocrinopathies, particularly because of the rapid onset and severity of symptoms with atypical presentation. Ectopic pituitary adenomas, especially those in the nasal cavity, nasopharynx, or paranasal sinuses, are easily misidentified. Any patient presenting with signs and symptoms of Cushing syndrome without any obvious pituitary adenoma or other sources of hypercortisolemia should be thoroughly screened for an ectopic adenoma. However, as with the case presented here, the coincident existence of a sellar mass should not preclude the possibility of an ectopic source. There should be a high degree of clinical suspicion for any mass in the general area surrounding the sella when evaluating Cushing syndrome.

Ectopic ACTH-secreting pituitary adenomas within the sphenoid sinus

Ectopic pituitary adenomas are defined by the presence of adenomatous pituitary tissue outside the sella and distinctly separate from the pituitary gland. Ectopic ACTH-secreting pituitary adenomas (EAPAs) are a rare cause of Cushing's syndrome. Detecting these radiologically can prove difficult, in part, due to their typically small size and unpredictable anatomical location. In ACTH-dependent Cushing's syndrome, if, despite comprehensive testing, the source of excess ACTH remains occult (including negative work up for ectopic ACTH syndrome) thought should be given to the possibility of the patient harboring an EAPA. In most cases, ectopic ACTH pituitary adenomas within the sphenoid sinus will manifest with symptoms of hormonal excess, have an obvious sphenoid sinus mass on pre-operative imaging and will demonstrate resolution of hypercortisolism after surgical excision if located and removed. Twenty cases of EAPAs have been reported in the literature to date. This paper will review the current literature on all previously reported EAPAs within the sphenoid sinus in addition to the current case.

Nasally located ectopic ACTH-secreting pituitary adenoma (EAPA) causing Nelson's syndrome: diagnostic challenges

PURPOSE

We report the first case of an Ectopic adrenocorticotrophin (ACTH)-secreting pituitary adenoma (EAPA) located within the posterior nasal septum associated with Nelson's syndrome, which eluded diagnosis for over a decade. In this report, we explore the reasons for such diagnostic difficulty and suggest ways in which an earlier diagnosis may be made.

METHODS AND RESULTS

A 19 years old Lebanese man presented in 2000, with overt Cushing's syndrome confirmed with markedly elevated urine free cortisols and failed dexamethasone suppression tests. An unsuppressed ACTH and a possible 5 mm adenoma on MRI (Magnetic Resonance Imaging) pituitary suggested Cushing's disease. The patient underwent trans-sphenoidal surgery (TSS), but histology revealed normal pituitary tissue and Cushing's syndrome persisted. A repeat MRI pituitary showed no anomaly, and extensive investigations failed to locate an ectopic lesion. Subsequently a bilateral adrenalectomy was performed. Over the ensuing years, the patient developed Nelson's syndrome with hyperpigmentation and markedly elevated ACTH levels. Repeated high dose dexamethasone suppression tests, corticotrophin releasing hormone (CRH) tests, and CRH stimulated inferior petrosal sinus samplings (IPSS) suggested a pituitary origin of the ACTH. Two further TSS were unsuccessful. The pituitary was irradiated. Subsequent review of his previous MRIs revealed an enlarging mass within the posterior nasal septum, which was excised in 2011. The histology confirmed the diagnosis of an EAPA within the nasal septum.

CONCLUSION

Ectopic ACTH-secreting pituitary adenomas can occur not only along the developmental route of Rathke's pouch, but other aberrant locations giving a clinical and biochemical picture identical to Cushing's disease or Nelson's syndrome. Clinicians should suspect an EAPA, when a central ACTH source seems to be apparent with no obvious pituitary adenoma. A detailed MRI involving possible EAPA sites aids in locating these unusual lesions.

Hypercortisolaemia due to ectopic adrenocorticotropic hormone secretion by a nasal paraganglioma: a case report and review of the literature

BACKGROUND

Adrenocorticotropic hormone-producing extraadrenal paragangliomas are extremely rare. We present a case of severe hypercortisolemia due to ectopic adrenocorticotropic hormone secretion by a nasal paraganglioma.

CASE PRESENTATION

A 70-year-old Caucasian woman, was emergently admitted to our department with supraventricular tachycardia, oedema of face and extremities and hypertensive crisis. Initial laboratory evaluation revealed severe hypokalemia and hyperglycemia without ketoacidosis, although no diabetes mellitus was previously known. Computed tomography revealed a large tumor obliterating the left paranasal sinus and a left-sided adrenal mass. After cardiovascular stabilisation, a thorough hormonal assessment was performed revealing marked adrenocorticotropic hormone-dependent hypercortisolism. Due to the presence of a cardiac pacemaker magnetic resonance imaging of the hypophysis was not possible. [68Ga-DOTA]-TATE-Positron-Emission-Tomography was performed, showing somatostatin-receptor expression of the paranasal lesion but not of the adrenal lesion or the hypophysis. The paranasal tumor was resected and found to be an adrenocorticotropic hormone-producing paraganglioma of low-proliferative rate. Postoperatively the patient became normokaliaemic, normoglycemic and normotensive without further need for medication. Genetic testing showed no mutation of the succinatdehydrogenase subunit B- and D genes, thus excluding hereditary paragangliosis.

CONCLUSION

Detection of the adrenocorticotropic hormone source in Cushing's syndrome can prove extremely challenging, especially when commonly used imaging modalities are unavailable or inconclusive. The present case was further complicated by the simultaneous detection of two tumorous lesions of initially unclear biochemical behaviour. In such cases, novel diagnostic tools - such as somatostatin-receptor imaging - can prove useful in localising hormonally active neuroendocrine tissue. The clinical aspects of the case are discussed and relevant literature is reviewed.

Detection of paranasal ectopic adrenocorticotropic hormone-secreting pituitary adenoma by Ga-68-DOTANOC positron-emission tomography-computed tomography

Ectopic adrenocorticotropic hormone (ACTH)-secreting tumors account for approximately 10% of Cushing's syndrome (CS). We present an extremely rare case of a patient with CS caused by an ectopic ACTH-secreting pituitary adenoma (EAPA) of the ethmoid sinus. The tumor was identified by positron-emission tomography-computed tomography (PET/CT) using the somatostatin receptor analogue Ga-68-DOTANOC. Transnasal endoscopic resection was performed and the patient showed significant clinical improvement with normalization of the endocrine pituitary axis. Immunostaining showed a somatostatin receptor 2 and 5-positive ACTH-producing adenoma. In patients with ectopic ACTH secretion, Ga-68-DOTANOC-PET/CT may play an important role in the localization of EAPA. Transnasal endoscopic resection is the therapy of choice.

Ectopic sphenoid sinus pituitary adenoma (ESSPA) with normal anterior pituitary gland: a clinicopathologic and immunophenotypic study of 32 cases with a comprehensive review of the english literature

Ectopic sphenoid sinus pituitary adenoma (ESSPA) may arise from a remnant of Rathke's pouch. These tumors are frequently misdiagnosed as other neuroendocrine or epithelial neoplasms which may develop in this site (olfactory neuroblastoma, neuroendocrine carcinoma, sinonasal undifferentiated carcinoma, paraganglioma, melanoma). Thirty-two patients with ESSPA identified in patients with normal pituitary glands (intact sella turcica) were retrospectively retrieved from the consultation files of the authors' institutions. Clinical records were reviewed with follow-up obtained. An immunohistochemical panel was performed on available material. Sixteen males and 16 females, aged 2-84 years (mean, 57.1 years), presented with chronic sinusitis, headache, obstructive symptoms, and visual field defects, although several were asymptomatic (n = 6). By definition, the tumors were centered within the sphenoid sinus and demonstrated, by imaging studies or intraoperative examination, a normal sella turcica without a concurrent pituitary adenoma. A subset of tumors showed extension into the nasal cavity (n = 5) or nasopharynx (n = 9). Mean tumor size was 3.4 cm. The majority of tumors were beneath an intact respiratory epithelium (n = 22), arranged in many different patterns (solid, packets, organoid, pseudorosette-rosette, pseudopapillary, single file, glandular, trabecular, insular). Bone involvement was frequently seen (n = 21). Secretions were present (n = 16). Necrosis was noted in 8 tumors. The tumors showed a variable cellularity, with polygonal, plasmacytoid, granular, and oncocytic tumor cells. Severe pleomorphism was uncommon (n = 5). A delicate, salt-and-pepper chromatin distribution was seen. In addition, there were intranuclear cytoplasmic inclusions (n = 25) and multinucleated tumor cells (n = 18). Mitotic figures were infrequent, with a mean of 1 per 10 HPFs and a <1% proliferation index (Ki-67). There was a vascularized to sclerotic or calcified stroma. Immunohistochemistry highlighted the endocrine nature of the tumors, with synaptophysin (97%), CD56 (91%), NSE (76%) and chromogranin (71%); while pan-cytokeratin was positive in 79%, frequently with a dot-like Golgi accentuation (50%). Reactivity with pituitary hormones included 48% reactive for 2 or more hormones (plurihormonal), and 33% reactive for a single hormone, with prolactin seen most frequently (59%); 19% of cases were non-reactive. The principle differential diagnosis includes olfactory neuroblastoma, neuroendocrine carcinoma, melanoma, and meningioma. All patients were treated with surgery. No patients died from disease, although one patient died with persistent disease (0.8 months). Surgery is curative in the majority of cases, although recurrence/persistence was seen in 4 patients (13.8%). In conclusion, ESSPAs are rare, affecting middle aged patients with non-specific symptoms, showing characteristic light microscopy and immunohistochemical features of their intrasellar counterparts. When encountering a tumor within the sphenoid sinus, ectopic pituitary adenoma must be considered, and pertinent imaging, clinical, and immunohistochemical evaluation undertaken to exclude tumors within the differential diagnosis. This will result in accurate classification, helping to prevent the potentially untoward side effects or complications of incorrect therapy.

An ACTH-secreting pituitary adenoma within the sphenoid sinus

A 68-year-old woman developed Cushingoid features three months prior to admission. She was found to have a markedly elevated plasma ACTH-cortisol level. Magnetic resonance imaging (MRI) revealed a mass in the left sphenoidal sinus, which had become enlarged to a point where it could not be removed by transsphenoidal surgery. We decided to proceed with radiation therapy to shrink the tumor. However, it was ineffective. Despite a reduction in serum cortisol levels using metyrapone, she died of septic shock. We describe a rare case of an ACTH-secreting pituitary adenoma within the sphenoid sinus.

Cyclic Cushing syndrome due to an ectopic pituitary adenoma

BACKGROUND

A 39-year-old man was referred to an endocrinology clinic for evaluation of his Cushing syndrome. He had gained 20 kg over 5 years and complained of intermittent headaches and easy bruisability. His medical history included a left foot fracture associated with minimal trauma 2 years earlier, hypertension, and stable Crohn disease with no use of exogenous glucocorticoids for at least 10 years.

INVESTIGATIONS

Measurements of plasma adrenocorticotropic hormone, 24 h urine free cortisol excretion, late-night salivary cortisol, serum cortisol levels before and after corticotropin-releasing hormone administration during a dexamethasone suppression/corticotropin-releasing hormone-stimulation test, pituitary MRI, and inferior petrosal sinus sampling.

DIAGNOSIS

Cyclic Cushing syndrome secondary to an ectopic pituitary adenoma.

MANAGEMENT

The cyclic nature of Cushing syndrome was suggested by the absence of hypercortisolemia during inferior petrosal sinus sampling, and was confirmed by multiple 24 h urine free cortisol measurements. The patient underwent transsphenoidal surgery, during which a 5 mm firm, round, midline sphenoid sinus lesion was identified and resected. In preoperative imaging studies, this lesion had been interpreted as being a mucosal polyp. At microscopic examination, the lesion was found to be a pituitary adenoma, which stained diffusely with antiadrenocorticotropic-hormone antibodies. Explorations of the sella and pituitary did not reveal any abnormalities. Postoperatively, the patient became hypocortisolemic and his cushingoid features resolved. His adrenal function normalized 3 months after surgery. At 18 months, the patient continued to be symptom-free with normal levels of urinary-free cortisol and midnight salivary cortisol.

Ectopic pituitary adenoma presenting as midline nasopharyngeal mass

INTRODUCTION

Ectopic pituitary adenomas are extremely rare. We report a case of ectopic pituitary adenoma in the midline of the nasopharynx. This adenoma probably arose from the pharyngeal remnant of Rathke's pouch.

METHODS

We discuss a case of a lady who presented to our unit with 2 months history of dryness and sensation of lump in her throat and a long standing history of hypothyroidism. Examination of nasopharynx revealed a smooth and fluctuant midline mass. CT scan of nose and paranasal sinuses confirmed the midline mass with small defect communicating with the sphenoid sinus. An initial diagnosis of Thornwaldt's cyst was made and she underwent upper aerodigestive tract endoscopy and marsupialization of the mass. Histopathological examination revealed ectopic pituitary adenoma.

CONCLUSION

Ectopic pituitary adenoma is an important differential diagnosis for a midline nasopharyngeal mass. It is recommended that prior to surgical resection of midline nasopharyngeal mass biopsy is taken and MRI is performed.

The application of the combined corticotropin-releasing hormone plus desmopressin stimulation during petrosal sinus sampling is both sensitive and specific in differentiating patients with Cushing's disease from patients with the occult ectopic adrenocorticotropin syndrome

CONTEXT

Although bilateral inferior petrosal sinus sampling (BIPSS) with CRH stimulation is the most accurate procedure for the differential diagnosis of ACTH-dependent Cushing's syndrome (CS), 4-15% of patients with Cushing's disease (CD) fail to demonstrate diagnostic gradients. Preliminary data suggest that a more potent stimulation by the combined administration of CRH plus desmopressin during BIPSS may provide some diagnostic advantage. A crucial issue, however, is whether such an amplified stimulation may affect the specificity of the procedure, and this was the main aim of the present study.

OBJECTIVE

We investigated the diagnostic accuracy of BIPSS performed by CRH plus desmopressin stimulation.

DESIGN AND SETTING

A retrospective analysis was conducted at a single tertiary care center.

PARTICIPANTS

Fifty-four patients were admitted for the investigation of ACTH-dependent CS. CD was diagnosed in 47 patients; occult ectopic ACTH syndrome (oEAS) was histologically confirmed in seven patients.

INTERVENTION(S)

All patients underwent BIPSS with CRH plus desmopressin administration. Additional noninvasive tests included CRH test, high-dose dexamethasone suppression test, desmopressin test, and pituitary magnetic resonance imaging.

MAIN OUTCOME MEASURES

Gradients of inferior petrosal sinus (IPS) to peripheral (IPS/P) ACTH were calculated before and after stimulation with CRH plus desmopressin.

RESULTS

The sensitivity for a basal IPS/P gradient greater than 2 was 61.7%, with 100% specificity and a diagnostic accuracy of 66.7%. After stimulation with CRH plus desmopressin, receiver operating characteristic (ROC) curve analysis showed that a cutoff gradient of more than 2 offers the best test performance. In total, 46 of 47 patients with CD had an IPS/P gradient greater than 2, but none of the patients with oEAS, resulting in a sensitivity of 97.9%. The specificity was 100%, diagnostic accuracy was 98.2%, and the positive and negative predictive values were 100 and 87.5%, respectively. A subgroup of 18 patients (16 with CD and two with oEAS) had contradictory responses to routine tests with CRH and/or high-dose dexamethasone suppression test; sensitivity, specificity, and accuracy of BIPSS in this subgroup were 100%.

CONCLUSIONS

The application of a combined stimulation with CRH plus desmopressin during BIPSS is associated with a high sensitivity but no loss of specificity.

An aberrant ACTH-producing ectopic pituitary adenoma in the sphenoid sinus

A 32-year-old woman with an ectopic adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma (EAPA) is presented. She had rapidly gained weight and suffered recurrent facial acne for a few years but lacked the typical Cushingoid features. Endocrine examinations revealed that her plasma ACTH was markedly high (196 to 280 pg/ml) without showing normal circadian rhythm and failed to respond to corticotropin-releasing hormone stimulation. Her cortisol levels ranged from 22 to 30 microg/dl throughout observation but low doses (1 and 2 mg) of dexamethasone failed to suppress either ACTH or cortisol level. Magnetic resonance imaging study revealed a 3-cm mass occupying the sphenoidal sinus with partial enhancement by gadolinium, which was separated from the normal pituitary in the sella region. The tumor resected by transsphenoidal surgery was histologically diagnosed as an ACTH-producing pituitary adenoma. After surgery her weight gain and acne remitted in accordance with decreases in plasma ACTH. Analysis of patient plasma by gel filtration method revealed the existence of big ACTH molecules eluted with a peak of authentic 1-39 ACTH, suggesting that this biologically less-active ACTH might be the reason why overt features of Cushing's syndrome failed to develop in this case. Although EAPA is clinically rare in parasellar disorders, the presence of ectopic pituitary adenoma should be considered in such cases showing ACTH hypersecretion without typical Cushingoid features.

Ectopic pro-opiomelanocortin syndrome

Ectopic POMC syndrome remains one of the most challenging differential diagnoses in endocrinology. Recent progress in the understanding of the tissue specific regulation of POMC gene expression and new insights into the processing of the POMC peptide in nonpituitary tissues has helped elucidate some of the molecular events leading to ectopic expression and secretion of POMC peptides. Corticotropin and other POMC-derived peptides have diverse effects on adrenal steroidogenesis, growth, and extra-adrenal tissues. Differences in POMC gene regulation in the corticotrope versus ectopic POMC-producing tumors provides a scientific framework for the clinical distinction between eutopic and ectopic Cushing's syndrome. In an attempt to revisit recent basic and clinical advances in the diagnosis of ectopic POMC syndrome the authors undertook an extensive literature review of 530 cases in 197 published papers and provided a molecular biologic, demographic and diagnostic update. According to this review, the four most common causes of ectopic POMC syndrome are the small cell carcinoma of the lung (27%), bronchial carcinoids (21%), islet cell tumor of the pancreas (16%), and thymic carcinoids (10%). Although the clinical features of patients with ectopic POMC syndrome are similar to those with Cushing's disease, subgroup analysis reveals a broad spectrum of severity and progression of signs and symptoms of hypercortisolism. The endocrine workup of a patient with suspected ectopic POMC syndrome includes the establishment of pathologic hypercortisolism, diagnosis of corticotropin dependency, and the differential diagnosis of corticotropin-dependent Cushing's syndrome. The use of a variety of baseline endocrine values, dynamic endocrine testing, and invasive procedures leads to the correct diagnosis in the majority of patients with ectopic POMC syndrome. Diagnostic imaging, including conventional radiological techniques and somatostatin receptor scintigraphy, aids in the correct localization and eventual treatment of ectopic POMC production.

Diagnosis and differential diagnosis of Cushing's syndrome

The clinical recognition of Cushing's syndrome and its biochemical confirmation is a challenging problem. The best diagnostic approach to patients with suspected Cushing's syndrome is still evolving. The traditional diagnostic approach of urine free cortisol and low-dose dexamethasone suppression testing may be inadequate when the degree of hypercortisolism is mild. Late-night salivary cortisol determinations may evolve as the simplest means of screening patients for suspected hypercortisolism. Repeated measurements of cortisol secretion (urine free cortisol or late-night salivary cortisol) over an extended period of time may be necessary to provide diagnostic certainty. The dexamethasone-CRH test is a reasonable approach in patients with equivocal data. The introduction of reliable, sensitive, and specific plasma ACTH measurements, the use of IPSS for ACTH with CRH stimulation, and the improved techniques of pituitary and adrenal imaging have made the differential diagnosis of Cushing's syndrome relatively straightforward (see Fig. 2). Clinicians who have never missed the diagnosis of Cushing's syndrome or have never been fooled by attempting to establish its cause should refer their patients with suspected hypercortisolism to someone who has.