Failure of total hypophysectomy to remove intrasellar microadenoma in cushing's disease

Nelson's syndrome due to an intracavernous corticotropin-secreting adenoma

OBJECTIVE

To report the first case of Nelson's syndrome due to an ectopic intracranial corticotropin-secreting tumor arising entirely within the cavernous sinus.

METHODS

We present a case report of Nelson's syndrome with clinical, laboratory, and radiologic features throughout a 25-year period.

RESULTS

A 54-year-old woman had been treated for Cushing's disease with bilateral adrenalectomy in 1971. Subsequently, Nelson's syndrome developed, and she had severe generalized hyperpigmentation and substantially increased plasma corticotropin levels. In 1976, she underwent a transsphenoidal hypophysectomy. Postoperatively, despite the development of panhypopituitarism and diabetes insipidus, she remained hyperpigmented and had persistently increased plasma corticotropin levels. Throughout the years, efforts to identify the site of the corticotropin-secreting tumor were unsuccessful until 1988, when magnetic resonance imaging revealed a mass in the right cavernous sinus; subsequently, petrosal sinus cannulation corroborated the intracavernous source of excess corticotropin. Cobalt-60 gamma knife radiotherapy in 1992 was followed by a clinical and hormonal response 4 1/2 years later.

CONCLUSION

This report describes only the second reported case of an intracranial corticotropin-secreting tumor arising entirely within the cavernous sinus and the first such case associated with Nelson's syndrome. Although rare, the possibility of an ectopic intracranial or extracranial pituitary adenoma should be considered in patients with pituitary hypersecretion without clear-cut intrasellar abnormalities or those with no response to surgical resection of the pituitary gland.

Ectopic corticotroph adenoma in the cavernous sinus: case report

OBJECTIVE AND IMPORTANCE

Adrenocorticotropin (ACTH)-secreting pituitary adenomas causing Cushing's disease are often difficult to identify because of their variable locations and their small size. This report presents histological evidence of an ectopic ACTH-secreting adenoma located entirely within the cavernous sinus.

CLINICAL PRESENTATION

A 62-year-old woman presented with central obesity, hypertension, and osteoporosis. Endocrinological evaluation suggested the presence of an ACTH-secreting pituitary adenoma; however, imaging studies, including dynamic magnetic resonance imaging, did not reveal any visible lesions in the pituitary gland. Bilateral cavernous sinus sampling demonstrated a large central/peripheral ACTH gradient, with a right/left ACTH gradient. The patient was treated as having pituitary-dependent Cushing's disease, until she died suddenly as a result of acute respiratory failure.

INTERVENTION

In a postmortem histological examination, an ACTH-secreting adenoma was found in the right cavernous sinus, which was completely surrounded by dura mater and had no direct connection with the pituitary gland.

CONCLUSION

Although they are rare, such adenomas located in the cavernous sinus should be recognized as one of the reasons for inaccurate cavernous sinus sampling and the failure of transsphenoidal surgery for patients with ACTH-dependent Cushing's syndrome.