Use of immunohistochemical and morphologic methods for the identification of human growth hormone-producing pituitary adenomas

Pituitary adenomas in acromegaly: Comparison of different adenoma types with clinical data

Adenoma tissues from 309 patients with active acromegaly was examined by routine light microscopy and immunohistochemistry, and selectively by electron microscopy. All adenomas were immunoreactive for growth hormone. Eighty-seven adenomas were monohormonal (28%), 58 were bihormonal (immunoreactive for growth hormone and prolactin) (19%), and 157 adenomas were plurihormonal (51%), with positivity for glyco-proteins and/or their α-subunit as well. The mean tumor size was significantly greater in monohormonal adenomas than in other adenoma types. There was no difference in invasiveness among the various adenoma types. Younger patients showed invasive tumor growth more often. Patients with densely granulated GH cell adenomas had a significantly longer duration of symptoms compared to patients with other adenoma types. More than half of the patients with sparsely granulated GH cell adenomas had a duration of less than 5 yr. There was no correlation between duration of symptoms and tumor size. The preoperative mean GH level was significantly higher in patients with sparsely granulated GH cell adenomas than in those with mixed GH/PRL cell adenomas. The preoperative mean PRL level was significantly higher in patients with bihormonal adenomas than in those with plurihormonal adenomas. There was an inverse correlation between age and preoperative GH and PRL levels. No linear correlation was found between preoperative basal GH and PRL levels. Monohormonal adenomas presented more often with suprasellar and/or parasellar extension than other adenoma types. Our data suggest a positive correlation between tumor extension and preoperative GH and PRL levels. Patients with plurihormonal adenomas were significantly older than patients with sparsely granulated GH cell adenomas and mixed GH/PRL cell adenomas. No significant difference was found between the various adenoma types and the extent of surgical removal, which depends on the degree of invasiveness, tumor size, and extrasellar tumor extension.

Relationships between pathological diagnosis and clinical parameters in acromegaly

From our series of 185 somatotropic adenomas with acromegaly, we found that sparsely granulated adenomas were more frequent (56%) than densely granulated ones. Immunocytochemistry detected growth hormone (GH) plurihormonal adenomas in 68% of patients. GH-alpha-subunit (alpha SU) and GH-alpha SU-prolactin (PRL) were more frequent (38%) than GH monohormonal adenomas (32%). The colocalization of GH and alpha SU in the same cell was obvious in many tumors. In contrast, colocalization of GH and PRL was demonstrated in only 25% of GH-PRL adenomas. The relationships between age, sex, tumor size, GH and PRL plasma levels, granularity, and percentage of GH-, alpha SU-, and PRL-immunoreactive cells were established in 105 acromegalic patients by three statistical methods, mainly by a principal component analysis. Correlations were found between the percentage of alpha SU- and GH-immunoreactive cells, and between densely granulated character and the percentage of GH-immunoreactive cells. Tumor size was not correlated with alpha SU, but was positively correlated with PRL plasma levels. Patients' age and percentage of GH-immunoreactive cells were inversely related to tumor size. Plurisecretion and sparsely granulated aspect are not related to age and tumor size.

Pathobiologic study of pituitary tumors: report of 62 cases with a review of the recent literature

Advances in radioimmunoassay procedures, immunocytochemistry, neuroradiologic imaging, and the surgical and medical treatment of pituitary adenomas have led to reappraisal of their classification as well as refinements in the diagnostic approaches used by pathologists. Sixty-two pituitary adenomas are described, and recent advances in this field are reviewed. Most of the patients were adults, but one of the adrenocorticotropic hormone (ACTH)-producing adenomas occurred in an 11-month-old infant. Endocrine-inactive tumors (43.5 per cent) were less common than hormone-producing tumors (56.5 per cent). Local invasion was most common in the former group, followed by ACTH-producing and other hormone-producing tumors. Ultrastructural features correlated with hormonal levels in the growth hormone(GH)-secreting tumors but not in the prolactin(LTH)- or ACTH-producing tumors. The formation of 7-nm filaments in the cytoplasm of tumor cells, corresponding to Crooke's hyaline change on light microscopy, was characteristic of ACTH-producing tumors. Ultrastructural changes in the ACTH granules suggested that the filaments may be derived from the feedback action of cortisol. Prior to surgery, a Rathke's cleft cyst and a chordoma were mistaken for endocrine-inactive pituitary adenomas. In two additional cases ectopic ACTH-producing tumors of lung clinically mimicked pituitary adenoma. Conversely, one pituitary adenoma mimicked sphenoid wing meningioma. Clinical, hormonal, and radiologic data and immunocytochemical and electron microscopic studies are needed for accurate pathologic interpretation and classification of pituitary adenomas.

Pituitary adenomas producing growth hormone in acromegalic patients

Growth hormone was shown in histological sections of 25 pituitary adenomas from acromegalic patients by means of the unlabelled peroxidase-antiperoxidase (PAP) technique. On the basis of the numbers of cytoplasmic granules, the cells of the adenomas were of two types: densely granulated and sparsely granulated. The densely granulated cells had abundant cytoplasm containing numerous granules, whereas the sparsely granulated cells had little cytoplasm with scanty granules. Depending on the predominant cell type the adenomas were also classified as densely granulated or sparsely granulated: 21 of the 25 adenomas (84%) were densely granulated and four (16%) sparsely granulated. There was some variation, however, in the relative numbers of the two types of cell from one part of an adenoma to another, a feature consistent with one type of cell in different phases of activity. There was no significant difference in mean serum growth hormone concentrations between the two groups, and granularity of the adenomas in histological sections did not therefore correlate with secretory activity. Nine adenomas showed extrasellar extension. The mean serum growth hormone concentration in these cases was lower than the mean of the adenomas confined to the sella turcica. Thus the size of the tumour did not correlate with the serum growth hormone concentration. Three of the four adenomas in the sparsely granulated group showed extrasellar extension, compared with 6 of 21 classified as densely granulated. This suggests that sparsely granulated adenomas have a more aggressive pattern of behaviour, but histological evidence for this was lacking.

Morphofunctional study of pituitary adenomas with acromegaly by immunoperoxidase technique and electron microscopy

In attempting to establish a functional classification of acidophilic adenomas of the pituitary gland, immunoperoxidase staining techniques specific for growth hormone (GH), prolactin (PRL), and luteinizing hormone (LH) were carried out. Surgically removed specimens from 24 acromegalic patients were studied. The pathologic observations were then compared with the basal plasma levels of each of the hormones. The existence of GH was demonstrated in all patients. Immunohistologically, GH-secreting adenomas could be subdivided into three types: Type I had the highest plasma-GH level (average 121 ng/ml), while the average plasma-GH levels of types II and III were 103 ng/ml and 73 ng/ml, respectively. This result suggested that the serum-GH level may correlate with the GH cell population in a tumor. In 13 of the acromegalic patients, immunoenzyme methods were utilized in order to identify prolactin cells. No clear correlation between serum-PRL levels and the distribution of PRL cells could be demonstrated. A few immunoreactive LH cells were found in 13 patients. These LH cells may be a mixture of normal cells, based on our clinical finding.

Morphological and biochemical relationships in 31 human pituitary adenomas with acromegaly

In 22 pure GH cell adenomas and 9 mixed GH cell-prolactin cell adenomas with acromegaly, we compare the morphological and functional data (secretory activity and granular appearance) with GH levels (radioimmunoassays) in the blood and in the tumor. According to morphological criteria, the secretory activity is marked in 13 cases (Group I), mild in 9 cases (Group II), and weak in 9 others (Group III). The mean values of the plasma GH levels in the 3 groups (80 ng/ml plus or minus 22; 26.5 ng/ml plus or minus 2; and 16.89 ng/ml plus or minus 2 respectively) are significantly different. In 17 densely granulated adenomas and 14 sparsely granulated adenomas, the plasma GH values were very variable. The mean levels of these 2 groups (49.76 ng/ml plus or minus 22 and 41.8 ng/ml plus or minus 7.8 respectively) are not significantly different. The GH concentrations in the tumor were also very variable (358 to 78,900 ng/mg). Their highly significant relationship with the granular appearance is an indirect proof of the granular localisation of GH. We distinguish between 4 functional aspects of the GH cell adenoma which define the different levels of synthesis, storage, and excretion. The secretory activity of the GH adenomatous cell varies with the adenomas and differs from that of the normal cell.

Demonstration of calcitonin and carcinoembryonic antigen (CEA) in medullary carcinoma of the thyroid (MCT) by immunoperoxidase technique

The presence of calcitonin and of carcinoembryonic antigen (CEA) was studied in six cases of medullary carcinoma of the thyroid using an immunoperoxidase technique. In five cases the material was obtained surgically and in one at autopsy. Tissue from primary tumours as well as from metastases was studied. Calcitonin and CEA were identified within all the tumours studied, although their pattern of distribution and staining intensity varied both within the cells and within the tumour. Some parts of the tumour contained both CEA and calcitonin, while others stained positively only for one of these substances. In some parts of the tumour there was no positive staining for either substance. Within the cells, CEA showed a typical linear distribution along cell surfaces, while calcitonin showed a more even cytoplasmic distribution and the deposits were more granular. Normal tissue surrounding tumour deposits did not show positive staining. It is considered that cells of medullary carcinoma of the thyroid contain both calcitonin and CEA. Identification of CEA and calcitonin in tumour tissue can be used as a diagnostic aid to identify medullary carcinoma of the thyroid. Iit is considered that these substances are being produced by this tumour and can be used as tumour markers.

Morphology and immunohistochemically-defined endocrine function of pancreatic islet cell tumours

Thirty pancreatic islet cell tumours were histologically classified and analysed for their possible peptide hormone content using the immunohistoperoxidase method. Seven tumours contained insulin, six tumours contained gastrin and eight tumours contained glucagon. One tumour contained all three hormones. In the insulin and gastrin-containing tumours, the cells were usually arranged in solid nests of cells, with tubular and acinar formations in about half the cases. In the glucagon-containing tumours the cells were mainly arranged in anastomosing ribbons consisting of one of two layers of small cells. Most of the hormone-containing tumours were argyrophilic using Grimelius' silver reaction. All but one of the glucagon-containing tumours were incidental findings at autopsy. About half of the other tumours had metastasized. It is concluded that a relation exists between the histological pattern of growth and immunohistochemically defined endocrine function of pancreatic islet cell tumours.

The influence of fixation on immunoperoxidase staining of plasmacells in paraffin sections of intestinal biopsy specimens

The influence of different fixation methods on the results of immunoperoxydase staining of immunoglobulin and gastrin producing cells in gastric and duodenal mucosa was investigated. An indirect method was used on paraffin sections. It appeared that that fixatives containing sublimate gave the most consistent results, a sublimate-formaldehyde mixture being the best.

Fluorescamine fluorescence detection of growth hormone-producing cells in human pituitary adenomas

Formalin-fixed and paraplast-embedded tissue specimens of human pituitary, thyroid, and pancreas were investigated using fluorescamine fluorescence and immunohistochemical methods. Growth hormone-producing cells present in normal and neoplastic pituitary tissue exhibited fluorescamine fluorescence. The other tissues examined showed no fluorescamine binding.