The pituitary fossa in Cushing's syndrome. A retrospective analysis of 93 patients

Cushing's syndrome: update of diagnosis and management

Although considerable advances have been made in the understanding of Cushing's syndrome in the recent past, many difficulties persist in the diagnosis and management of patients with hypercortisolism. Precision in the diagnosis of Cushing's syndrome and the differentiation of its various forms have gradually improved, but a substantial number of cases have laboratory or radiologic findings that can be misleading or at least difficult to interpret. Furthermore, other conditions may mimic Cushing's syndrome and add to the diagnostic difficulties. Surgical extirpation of primary adrenal lesions that cause the hypercortisolism or of the neoplasms responsible for the ectopic production of adrenocorticotropic hormone remains the treatment of choice for these problems. Currently, transsphenoidal surgical exploration is the treatment of choice for Cushing's disease.

Cushing's syndrome

Cushing's syndrome remains one of the most challenging problems in clinical endocrinology. Cushing's disease is caused in the majority of cases by basophil pituitary microadenomas which may be successfully treated by trans-sphenoidal hypophysectomy. Treatment with metyrapone or o,p'-DDD can always induce a clinical remission but not a cure, and neurotransmitter therapy may be effective in a minority of cases. Pituitary irradiation cures about half of cases in the long-term and may be used for surgical failures. Tumours producing ectopic ACTH are frequently benign, small and occult and may produce a syndrome clinically indistinguishable from Cushing's disease. Biochemical investigations cannot absolutely distinguish pituitary from ectopic sources of ACTH and therefore body CT scanning and percatheter venous sampling are essential diagnostic investigations. Tumour localization may result in resection and complete cure, although even small tumours may have a malignant potential. Adrenal tumours are readily diagnosed by plasma ACTH measurement and adrenal CT scanning. Adrenal adenomas are cured by adrenalectomy. Carcinomas may be treated by a combination of adrenalectomy, radiotherapy and o,p'-DDD, but long-term prognosis is poor.

Long term results of radical hypophysectomy for Cushing's disease

Sixteen consecutive cases of Cushing's disease were treated by radical transphenoidal hypophysectomy. Surgical removal was not possible in two cases. Of the other 14, there was total clinical and biochemical remission of the disease in 13 and partial remission in one. Some form of replacement therapy has been necessary in 11 out of the 14 cases. During a long period of postoperative clinical and biochemical assessment extending over 5-14 years (average 8 years) there have been no recurrences.

CT abnormalities of the pituitary in hyperprolactinaemic women with normal or equivocal sellae radiologically

Sixteen young women with hyperprolactinaemia and normal or equivocal sella in radiographs underwent computed tomography using a Siemens Somatom II. In all but one case an abnormality was found. The sella was full in seven and partially empty in nine. A tumour was visible in six of the full and in four of the partially empty sellae. All but one of the 10 tumours was unilateral, and in seven the pituitary stalk was deviated away from the tumour. After administration of intravenous contrast (Urografin) four tumours showed diffuse enhancement, four ring enhancement, and two enhanced less than adjacent normal pituitary tissue. Two of the tumours have been subsequently shown histologically to be prolactinomas. Prolactin response to thyrotrophin-releasing hormone predicted a tumour in seven out of eight with visible tumours but also in three out of four without visible tumours; using metoclopramide, a tumour was predicted in six out of seven with tumours, but again in three out of four without visible tumours. Such results question the value of dynamic tests for the discrimination of tumours. We conclude that practically all women with sustained hyperprolactinaemia and a normal or equivocal sella radiologically have pituitary disease.

Pituitary Cushing's syndrome and Nelson's syndrome: diagnostic criteria, surgical therapy, and results

Eight patients with pituitary Cushing's syndrome and 2 with Nelson's syndrome were followed from one to ten years after removal of pituitary adenomas. A detailed assessment of the pituitary-adrenal axis was obtained in all patients when last seen, save the first, who had undergone a complete hypophysectomy ten years previously. Long-term observations have shown sustained endocrine cure in 7 of 8 patients with pituitary Cushing's syndrome. One patient with Nelson's syndrome was also cured. There was no operative morbidity or mortality. There were no instances of diabetes insipidus. The long-term results in this study indicate that patients with pituitary Cushing's syndrome have a better than 90% chance of being cured after transsphenoidal removal of the pituitary (micro) adenomas. Current diagnostic and therapeutic concepts in the management of pituitary Cushing's syndrome are discussed in detail.

Some pitfalls in the diagnosis of pituitary tumours: the importance of carotid angiography

Headache and the radiological finding of an abnormal pituitary fossa are a frequent mode of presentation in patients with pituitary tumours. The case histories and radiological findings of 4 patients who presented with the above features, and in whom the major abnormalities of the pituitary fossa were due mainly to variations in the cavernous portions of the carotid artery, are described. The role of carotid angiography in the investigation of a patient with an abnormal pituitary fossa is stressed.

Cushing's disease: a review of pathogenesis, diagnostic methods, and treatment

Cushing's disease is a form of Cushing's syndrome that results from excessive ACTH secretion with consequent adrenal hyperplasia and increased cortisol secretion. Most patients have an ACTH-secreting tumor; in others, a hypothalamic defect may play an important role. Steroid determinations and the dexamethasone suppression test can confirm overproduction of cortisol. Measurement of basal plasma ACTH level is perhaps the most reliable way to determine the cause of overproduction. Transsphenoidal surgery seems to be the initial treatment of choice, if the necessary neurosurgical expertise is available. If it is not, bilateral adrenalectomy combined with conventional pituitary irradiation can be used. Other alternatives are cobalt 60 high-voltage or heavy-particle irradiation and drugs that interfere with cortisol biosynthesis.

Differences in secretion characteristics in Cushing's disease with and without radiologically evident pituitary tumors

In a group of 22 unselected patients with Cushing's disease 3 had a moderately enlarged pituitary fossa, while 6 patients showed asymmetry of the sella turcica at lateral tomography. This group of 9 patients with radiologically evident pituitary adenomas had:i) a higher average basal urinary excretion of 17-hydroxycorticosteroids which showed a greater day to day variation;ii) a greater (although insufficient) decrease of plasma cortisol in response to a single oral dose of 1 mg dexamethasone and larger postdexamethasone rebound excretion of urinary 17-hydroxycorticosteroids after 8 mg dexamethasone daily for two days; and iii) a larger maximal increase of plasma cortisol after lysine vasopressin administration than the other 13 patients. The increase in the size of a pituitary (micro-) adenoma in patients with Cushing's disease is accompanied by a more severe hypercortisolism and an increased responsiveness of the pituitary-adrenal axis to the manipulations mentioned.

Cushing's syndrome: a review of diagnostic tests

This review presents an analysis and interpretation of the published experimental data that form the basis for laboratory tests commonly used for screening, definitive diagnosis, and differential diagnosis in Cushing's syndrome. The single-dose overnight dexamethasone suppression test is excellent for screening outpatients since this test has a very low incidence of false-negative results (1.9% of 154 patients with Cushing's syndrome). The definitive diagnosis of Cushing's syndrome is best established by combining basal state measurements of the daily urine-free cortisol excretion and late evening plasma cortisol levels with the 2-mg low-dose dexamethasone suppression test. The etiology of Cushing's syndrome is best determined by combining measurements of basal state plasma adrenocorticotropin (ACTH) levels with the 8-mg high-dose dexamethasone suppression test. Under certain conditions, the basal state daily urine excretion of 17-hydroxycorticosteroids and 17-ketogenic steroids, the insulin tolerance test, and the metyrapone test may be useful in the definitive or differential diagnosis of Cushing's syndrome.