Cushing's syndrome and the hypophysis. A re-evaluation of pituitary tumors and hyperadrenalism

Functional Chromophobe Adenomas of the Canine Adenohypophysis

Chromophobe adenomas from 8 dogs with clinical signs and lesions of hyperadrenocorticism (Cushing's-like disease) were selected for electron microscopic study in order to establish a morphologic basis for active secretion by the neoplastic cells. At the level of ultrastructure there was definite evidence of secretory activity and the organelles concerned with protein synthesis (endoplasmic reticulum) and packaging of secretory products (Golgi apparatus) were well developed. Although the numerous secretory granules present varied in electron density and in size, the most frequently encountered granule measured 170 m μ in diameter. The secretory granules of the neoplastic cells differed from those found within acidophils and basophils of the canine hypophysis. Based on these findings it was concluded that the cells comprising these chromophobe adenomas were actively secreting corticotrophs of the pituitary gland.

Large pituitary adenomas with extension into the nasopharynx. Report of three cases with a review of the literature

Three cases of pituitary adenoma with extension into the nasopharynx and nasal cavity are reported. The occurrence of this rare tumor underscores the need to consider a pituitary tumor whenever a patient presents with rhinologic complaints and destruction of the sellar floor. Epistaxis, although exceptional, may be the first manifestation of a pituitary tumor. Immunohistochemical analysis combined with staining for the pituitary hormones proved to be essential for reaching a definite diagnosis. Magnetic resonance imaging seems to be the modality of choice for differentiation between tumorous and nontumorous sinus obstruction.

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.

Recurrence of chromophobe pituitary adenomas after operation and postoperative radiotherapy

The rate of recurrence is reported in a prospective study of 56 patients (28 men, 28 women) with large chromophobe pituitary adenoma (with or without hyperprolactinemia). The surgical approach was transfrontal in 44 and transseptosphenoidal in 12 patients. Cryoapplication was combined with the transsphenoidal operation. All but one patient received postoperative pituitary irradiation. Altogether, 11 (20%) clinical relapses (10 men) occurred between 0.5 and 6 years after the transfrontal operation. Patients that relapsed had had larger tumors than those remaining in remission. Occurrence of the tumors appeared with a deterioration of the visual field defect in 9 patients. There were no differences in the degrees of hypopituitarism in patients who relapsed as compared to patients remaining in remission.

Pituitary function after pituitary apoplexy

Pituitary function was studied in nine patients who had recovered from pituitary apoplexy. All the patients recovered spontaneously; none required immediate surgery. Four of the patients had acromegaly, two had pituitary-dependent Cushing's syndrome, and a "functionless" pituitary adenoma was found in three. Low serum growth hormone concentrations were observed in three patients with acromegaly whereas the concentration remained increased in the fourth one. Of the two patients with Cushing's syndrome, a selective ACTH-deficiency developed in one and Nelson's syndrome appeared with excessive secretion of ACTH in the other. Transient or persistent hypofunction of the anterior pituitary occurred in al patients. Three patients underwent hypophysectomy after respective intervals of three, eight and 12 months after pituitary apoplex. The operation revealed a hemorrhage in one functionless adenoma and a large cyst in another one. In the third patient who had acromegaly, no signs of the pituitary apoplexy were observed at operation.

The cells of origin of ACTH in man

The evidence from ACTH-producing tumors, from the morphologic effects of excess glucorticoids on the hypophysis, and from immunocytochemistry all points to the predominant "basophils" of the human anterior lobe, the intensely PAS-possitive beta(R) cells, as the source of ACTH. Similar cells often also occur, sometimes in large numbers, in the pars nervosa. beta(R) cells can be immunostained with antibodies against alphaMSH and betaMSH, but it is likely that they actually contain the precursor molecule(s) of betaMSH, betaLPH (and may be gammaLPH). Once this is satisfactorily documented, the functional term corticolipotrops should replace the provisional name beta(R) cells. Electron microscopically, these cells contain randomly arranged granules with a maximum diameter of 300-500 nm, and occasionally small amounts of filamentous material, which increases dramatically in response to excess glucocorticoids. In the beta (R) cells of adults, a single set of granules stains for ACTH and with antibodies to betaMSH. In fetal life, ACTH cells appear early and material reactive with anti-betaMSH accumulates in them (and possibly also in cells not containing ACTH) only later. The posterior lobe beta(R) cells can be immunostained with both anti-betaMSH and antibodies against the COOH-terminal portion of ACTH, but the presence of bioactive ACTH in them remains to be shown.

[Incidence and clinical features of pituitary tumours in cases of central Cushing's syndrome (author's transl)]

Approximately 10% of all patients with untreated central Cushing's syndromes have clinically verifiable tumours of the pituitary. After bilateral adrenalectomy 10 to 20% of patients with apparently normal pre-operative pituitary glands develop clinically and roentgenologically demonstrable pituitary tumours, of the so called Nelson type. These are usually very active chromophobe adenomas which are dangerous because they expand rapidly. They secretee considerable amounts of ACTH and MSH. A typical case is described.

The characterization of the ACTH produced by a primary pituitary tumour in a patient with Cushing's disease

The nature of ACTH present in pituitary tumours associated with Cushing's disease has not been previously characterized nor correlated with the electron microscopic appearance. The present report describes the culture of tumour tissue obtained from a patient with a pituitary tumour associated with Cushing's disease, and the characterization of the ACTH content of tumour and media by bioassay, immunoassay, and Sephadex G-50 gel filtration. Electron microscopic studies were also performed. The pathological diagnosis was pituitary adenoma with basophilic PAS-positive granules. Electron microscopy showed uniformity of size and shape of the tumour cells, the presence of secretory granules of varying size and density, and disorganized tubular and vacuolar arrays of endoplasmic reticulum. The bioreactive ACTH content of the tumour was 0-29 mug/g, which is markedly below that seen in the normal pituitary, but within the range reported for ectopic ACTH-producing tumours. Immunoreactive ACTH when measured by a C-terminal antibody was five-fold higher than when measured by an N-terminal antibody; the latter gave a value of 1-24 mjg/g. On Sephadex G-50 gel filtration, 9% of the N-terminal immunoreactivity was present in the Vo fraction ('big' ACTH). This latter fraction had a greater percentage of bioreactivity (28%) than previously reported for this molecular species. Analysis of the tumour culture medium revealed a variation in molecular size similar to that seen in the tumour, although the percentage of ACTH of large molecular size was greater, suggesting increased secretion of a possible 'prohormone' by the tumour. Plasma ACTH was characterized by a 2:1 ratio of immunoreactivity (N-terminal) to bioreactivity, and a 4:1 ratio of C-terminal/N-terminal immunoreactivity. This report also appears to be the first of successful short-term tissue culture of a primary ACTH-producing tumour. The granule size was considerably larger than that reported for normal pituitary ACTH-containing cells.

Ultrastructural classification of pituitary adenomas

Forty-eight surgically removed pituitary adenomas have been investigated by electron microscopy. Distinct differences in fine structural appearances permitted their separation into 5 classes: 1) Growth hormone, (GH)-cell tumors; 2) Prolactin cell tumors; 3) Mixed adenomas composed of GH and prolactin cells; 4) Adrenocorticotrophic-Melanocyte stimulating hormone (ACTH-MSH) cell tumors; 5) Undifferentiated cell adenomas. Densely and sparsely granulated tumors were distinguished within classes 1, 2 and 4. Although these two forms appeared to represent well defined entities, they may be variants of the same tumor differing only in pace of hormone production and/or release. Number and size of secretory granules varied considerably among tumors composed of the same cell type indicating that pituitary tumor classification cannot be based solely on granule morphology. This classification takes into account morphogenesis with emphasis on clinical features and structure-function relationship.

[Plasma ACTH and Nelson tumors in bilaterally adrenalectomized Cushing patients]

Bilaterally adrenalectomized patients (18) because of Cushing's syndrome were studied. 16 of these 18 persons exhibited fairly high plasma ACTH levels. Distinctly elevated plasma ACTH levels were observed in 6 of them. 5 patients of this group showed an enlarged sella and deep pigmentation of the skin. 4 of the latter group had a mucoid cell adenoma which was removed selectively. After the surgery the ACTH values were found to be within normal range without any significant endocrine dysfunction of the pituitary. A long-term ACTH survey revealed that the ACTH levels remained within the ranges of bilaterally adrenalectomized Cushing patients without concomitant enlargement of the sella or pigmentation.

Pituitary melanocorticotrophinoma with amyloid deposition

The light and electron microscopic features of a pituitary adenoma composed of adrenocorticotrophic hormone (ACTH) and melanocyte stimulating hormone (MSH) cells with perivascular amyloid deposition is reported. Histochemical and fine structural data indicate that this material is APUDamyloid and is present in the extra-cellular perivascular spaces. It is suggested that the differences in fine structure and of distribution of the amyloid in pituitary adenomas is dependent upon the cell of origin.

Pituitary apoplexy in a child. Case report

✓ A rapidly growing 6-year-old boy with progressive visual loss suddenly became blind following an acute hemorrhage into an eosinophilic adenoma. The case is described and discussed, including the successful operative treatment.

Pituitary apoplexy: a review and reappraisal

✓ The authors report their experience with nine cases of acute pituitary apoplexy; eight had proven chromophobe adenomas, and two of these patients had the clinical stigmata of Cushing's syndrome. One patient who displayed acromegalic features was treated with x-ray, and no pathological specimen was obtained. The outstanding clinical features of acute pituitary apoplexy were sudden headache, depressed consciousness, ophthalmoplegia, meningismus, and signs of compression of the optic nerve or chiasma. Clinical or laboratory evidence of severe hypopituitarism was rare. The apoplectic syndrome was the first indication of the presence of a pituitary tumor in all nine cases. In one case anticoagulant therapy (for an acute myocardial infarction) appeared to have precipitated hemorrhage in an unrecognized chromophobe adenoma. The authors suggest that acute pituitary apoplexy is a surgical emergency resulting from sudden ischemia, necrosis, and hemorrhage when an expanding pituitary neoplasm has become impacted at the diaphragmatic notch.