[Light and electron microscopic studies for classification of pituitary adenomas (author's transl)]

DNA pattern of human pituitary tumors

The tumor tissue from 62 consecutive patients with pituitary adenomas was analyzed with regard to ploidy and percentage of cells in different phases of the cell cycle by use of flow-cytofluorometry. In six of 62 cases, two tumor-cell populations were identified; therefore the study material comprised 68 cell lines. Approximately half of the cell lines were diploid (33 of 68, or 49 per cent); five of 68 (7 per cent) were hypodiploid, and 30 of 68 (44 per cent) were hyperdiploid-aneuploid. A low occurrence of aneuploid cell lines appeared in hormonally nonsecreting tumors (22 per cent). An aneuploid DNA pattern was predominantly found in prolactinomas (70 per cent). In acromegaly, tumors secreting growth hormone had only an aneuploid DNA pattern in 41 per cent of the cases, whereas 67 per cent of the tumors with concomitant secretion of growth hormone and prolactin were aneuploid. The latter group also comprised the largest number of adenomas with two cell lines and all but one hypodiploid tumor. Most tumors with an aggressive clinical course were either aneuploid or diploid but with a high percentage of proliferating cells.

Monomorphous plurihormonal adenoma of the human pituitary. A histologic, immunocytologic and ultrastructural study

A well-developed 23-year-old man, complaining of blurred vision but with no endocrine symptoms, was found to have a large pituitary adenoma spreading outside the sella. Endocrine investigations disclosed growth hormone deficiency, hyperprolactinemia (responsive to thyrotropin-releasing hormone), and very high blood alpha-subunit (72 ng/ml) level. Histology showed a chromophobic, slightly acidophilic pituitary adenoma with focal fibrosis and calcification. The immunoperoxidase technique revealed prolactin and alpha-subunit in the cytoplasm of a single-cell type, at the light and electron microscopic level, indicating that monomorphous, plurihormonal adenomas exist in the human pituitary. Immunostaining with antibodies raised against beta-thyroid stimulating hormone, beta-follicle stimulating hormone and alpha-endorphin were observed in scattered cells. Those cells that contained immunoreactive alpha-endorphin did not appear to contain alpha-subunit. The ultrastructural features of adenoma cells showed no resemblance to any known cells in nontumorous or tumorous pituitaries. It can be postulated that adenohypophysial cells, after neoplastic transformation, may have the ability to secrete a number of biochemically unrelated hormones, suggesting that during embryologic development they pass through a common progenitor cell stage, capable of plurihormonal activity.

Secretion of LH, FSH, and PRL shown by cell culture and immunocytochemistry of human functionless pituitary adenomas

Hormone secretion by ten functionless human pituitary adenomas in cell culture has been measured, and compared with tissue immunocytochemistry and electron microscopy, as well as results with a normal pituitary. Patients presented following routine x-ray and had no clinical or biochemical endocrine abnormality apart form one male with raised serum FSH and PRL, normal LH, and low testosterone. Of the ten adenomas, nine secreted both LH and FSH in cell culture and five of these also secreted PRL, one did not secrete any anterior pituitary hormones (ACTH was not measured). No GH or TSH was detectable in the cultures of the nine LH/FSH secretors excluding the possibility of contamination by normal anterior pituitary. The normal pituitary cells secreted all anterior pituitary hormones: the amounts of FSH/LH being comparable with those of the adenomas. Immunostaining confirmed the cell culture results and showed the adenoma FSH/LH cells to be scattered singly or in small groups of two to five cells with both hormones usually being in the same cell. PRL where found was in separate cells. Hormone granules were small (50-160nm), round or irregular and scattered in the cytoplasm of rounded cell of low secretory activity. The negatively staining cells were not different ultrastructurally to those staining positively. It is concluded that a significant proportion of functionless pituitary adenomas have detectable low levels of LH/FSH secretion often accompanied by PRL when examined by cell culture or immunocytochemistry. Although these adenomas were endocrinologically quiescent activity could have been masked because of post-menopausal secretion and one male probably had and FSH-secreting adenoma.

Aneuploid DNA pattern in human pituitary adenomas

The DNA contents of 29 histologically and ultrastructurally benign pituitary tumours were analyzed with flow-cytofluorometry.--Cytogenetic malignancy, i.e., aneuploidy, was found in 12 cases, independent of endocrinological type of tumour. In 17 cases a diploid DNA content occurred. In aneuploid tumours varying percentage of cells in S-phase was found indicating different growth patterns. Aneuploid DNA pattern was often found in young patients with a short case history. Our findings indicate that analysis of cellular DNA content may reflect the biological properties of pituitary tumours, independent of morphologic characteristics and type of hormone secretion.

Null cell adenoma of the human pituitary

Among 343 surgically-removed pituitary adenomas, 56 tumors were unassociated clinically or biochemically with increased hormone secretion and contained no adenohypophysial hormones by the immunoperoxidase technique, except for 10 cases in which a few scattered cells showed positive immunostaining for beta-TSH or beta-FSH, beta-LH, prolactin and/or alpha-subunit. These tumors were chromophobic adenomas with no PAS, lead hematoxylin or carmoisine positivity and electron microscopy failed to reveal their morphogenesis. The term null cell adenoma of the pituitary is proposed to designate this tumor type. This term recognizes the most obvious features of these tumors: the absence of markers which would permit the disclosure of their cellular origin. Null cells are also found in the nontumorous adenohypophysis, suggesting that null cell adenomas derive from preexisting nonneoplastic null cells. The question of whether pituitary null cells are hormonally inactive committed precursors, uncommitted stem cells or dedifferentiated cells remains to be elucidated.

Ultrastructure, immunohistochemistry and hormone release of pituitary adenomas in relation to prolactin production

Fifteen cases of pituitary adenoma, 14 of which were associated with hyperprolactinemia, were studied by observation and granule morphometry of electron micrographs, immunohistochemistry and sequential observation of in vitro release with regard to hormone production, storage and secretion. Adenoma cells of 6 cases with marked elevation of plasma prolactin were sparsely granulated, showed characteristic ultrastructures including the presence of small secretory granules, well developed Golgi and rough membranes, misplaced exocytosis, and positive or negative immunostaining for prolactin. These adenomas also showed vigorous release of the hormone into the circulation and/or culture medium. In vitro studies showed that negative immunostaining of adenoma cells did not preclude the production and secretion of the hormone. One densely granulated adenoma containing cells with numerous lactotroph type granules showed moderate release of prolactin into the circulation. In an acromegalic case associated with both high plasma growth hormone and prolactin, some cells were shown by immunohistochemistry to store both hormones There were 4 adenomas which could not be shown to produce, store and secrete prolactin by any method available.

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.

Dedifferentiation and invasive growth of an eosinophil pituitary adenoma

This report concerns the course of an eosinophil pituitary adenoma in an acromegalic female (16 years of age when first symptoms appeared) over a period of ten years. The case was complicated by craniocerebral trauma and CSF rhinorrhoea. After several operations, dedifferentiation, and invasive growth into the orbit and the petrous bone were observed with walling in of the VIIIth cranial nerve. The possible causes of the dedifferentiation of the adenoma are discussed.

[Morphology of the paraadenomatous adenohypophysis. A contribution to the pathogenesis of pituitary adenomas (author's transl)]

98 biopsies of the paraadenomatous adenohypophysis in acromegaly, galactorrhea combined acromegaly, isolated galactorrhea, hypothalamic-hypopphysial Cushing's disease. Nelson's syndrome, and in nonfunctional adenomas were studied by light microscopic methods in order to find evidence for a possible hyperplasiogenic origin of the different types of adenomas. It was hoped that the numerical relations and structures of hypophysial cells might provide significant information. Nodular ACTH cell-hyperplasia was found frequently apart from ACTH cell-tumors in Cushing's disease and Nelson's syndrome and on this basis we suggest that the adenomas in both diseases arise from hyperplasia. During their further development these adenomas seem to become autonomous, since the number of paraadenomatous ACTH cells decreased in bigger tumors. Some of the cases with isolated galactorrhea showed hyperplasia of acidophil and chromophobe cells in the paraadenomatous adenohypophysis. It can thus be assumed that porlactin cell-tumors also develop from prolactin cell-hyperplasia. Both the adenomas and the nonfunctional tumors in acromegaly seem to grow autonomously from the beginning, since paraadenomatous hyperplasia is seldom seen.

[Definition and differential diagnosis of chromophobe pituitary adenomas: light and electron microscopic studies]

INTRODUCTION

Chromophobe adenomas have been defined by the absence of secretory granules in them. But this definition has become doubtful since a granulation could be electron microscopically demonstrated. Hence we studied a collection of more than 100 surgically removed pituitary adenomas in order to find precise morphological criteria for the differential diagnosis of chromophobe adenomas, specially from the sparsely granulated chromophilic tumors. Furthermore we tried to find relations between the amount and type of granulation of the tumor cells and the clinical endocrine hyperfunction.

MATERIAL AND METHODS

108 unselected pituitary tumors were studied by light and electron microscopic methods. For histology the tissue was fixed in Helly's fluid or in buffered formalin. The paraffin wax sections were stained with haematoxylin-eosin, PAS, gallocyanin-chrome alum, carmoisine L-orange G-wool green, Herlant's tetrachrome method, and performic acid-alcian blue-PAS-orange G. For electron microscopy small pieces of the tumor were fixed in buffered glutaraldehyde, postfixed in osmium tetroxide, and embedded in epon 812. Sections were stained with toluidine blue for light microscopy. Thin sections were stained with uranyl acetate and lead citrate. Electron microscopical pictures with a primary magnification of 4000 were semi-quantitatively judged for the content and the extent of rough endoplasmic reticulum, Golgi complexes, secretory granules, lysosomes, and mitochondria by a grading with 6 degrees. Results. With special stains and the electron microscope 46 adenomas could be identified which consisted only of slightly granulated or agranular cells but not of densely granulated cells. These were defined as chromophobe adenomas. Oncocytic adenomas were regarded as another tumor type and were not included. One half of the chromophobe adenomas showed ultrastructurally well developed protein-synthesizing organellas. The diameter of the secretory granules amounts up to 500 mum. One quarter had many autolysosomes or lipid droplets. On the other hand, 18 adenomas of our collection exhibited moderate acidophilic granulation with only a few denser or fully granulated cells. These were designated as sparsely granulated acidophilic adenomas. They were rich in organelles. 89% of them showed a well developed rough endoplasmic reticulum and large Golgi complexes as signs of high endocrine activity. The secretory granules had diameters between 200 and 600 upsilonm. The autolysosomes were for the most part small and rare. The 20 fully granulated acidophilic adenomas could be easily recognized and are not discussed in this paper. The sparsely granulated mucoid cell-adenomas were easily identified by a positive PAS-reaction.

DISCUSSION

From our studies we conclude that chromophobe adenomas exhibit only sparse granulation and no denser or fully granulated tumor cell...

[Comparative light and electron microscopic studies of oncocytic pituitary adenomas (author's transl)]

In a collection of 108 surgically removed, light and electron microscopically studied pituitary tumors, 19 adenomas (17.6%) could be found of which oncocytic tumor cells constituted more than 50%. These showed histologically, in conformity with the criteria of oncocytes, a fairly broad cytoplasm with finely granular or, in part, finely vacuolar structures and distinct cell membranes. The nuclei were predominantly round and moderately rich in chromatin but also in part, pyknotic. In paraffin-embedded sections the tumors could not be distinguished with certainty from chromophobe or moderately granulated acidophil adenomas. In plastic-embedded sections they could be identified by the typical filmy and finely granular feature of the cytoplasm which was distinctly different from conglomerations of secretory granules. Ultrastructurally they were characterized by many densely packed mitochondria. These were, in part, hydropically swollen. Furthermore, 5 tumors exhibited increased hormone-synthesizing organelles, 2 of which induced an acromegaly. Probably the oncocytic pituitary adenomas are secondarily transformed chromophobe or moderately chromophil tumors which must be regarded as independent, for the most part endocrinologically inactive pituitary tumors. In addition to these purely or almost purely oncocytic tumors further 12 adenomas (11.1%) with oncocytic parts constituting between 10 and 50% of the tissue were in our collection. Of these, 5 were moderately or distinctly acidophil adenomas with clinical symptoms of acromegaly; 2 were, for the most part, mucoid cell adenomas with Nelson's syndrome.

[Pituitary adenomas of patients with galactorrhea. Light and electron microscopic studies (author's transl)]

A collection of 108 surgically removed pituitary adenomas was studied by histologic, immunohistochemical and electron microscopical methods. It included 7 predominantly chromophobe adenomas of patients whose clinical symptoms consisted of a pure galactorrhea. Ultrastructurally, 4 of these adenomas contained little endoplasmic reticulum so that an endocrine activity of the tumors could not be assumed. These cases represented inactive adenomas which probably led to a disturbance of the secretion of prolactin-inhibiting factor by suprasellar extension resulting in stimulation of the non-tumorous adenohypophysis and secondary hyperprolactinemia. Another 3 adenomas consisted of cells that showed histologic and immunocytochemical reactions of the same kind as normal prolactin cells. Electron microscopically, these adenoma cells exhibited a very well developed rough-surfaced endoplasmic reticulum, dilatation of the Golgi complexes, sparsely arranged pleomorphic secretory granules, an increased number of microtubules, and interdigitating microvilli formed by the cell membrane. These features resembled closely the characteristics of stimulated non-tumorous prolactin cells during lactation, and thus could be termed "prolactin cell adenomas". These tumors surely caused a hyperprolactinemia through their own hormone production. In addition 3 other adenomas were present which showed the same light and electron microscopic structures as the prolactin cell adenomas but did not cause galactorrhea. From the findings in these cases we assume that the tumors effected neither a clinically peculiar hyperprolactinemia nor produced an endocrinologically inactive polypeptide.