Immunohistochemical Evaluation of the Post-Translational Processing of Chromogranin A in Human Pituitary Adenomas

Chromogranin A (CgA), pancreastatin (PST), intervening-peptide (IP) and WE-14 antisera were employed to investigate the proteolysis of CgA in 50 pituitary adenomas. All non-functioning (NF) pituitary tumours (n = 28) exhibited CgA immunoreactivity. PST, IP and WE-14 immunostaining was observed in 85%, 89% and 67%, respectively. CgA, PST and 1P immunostaining were comparable in the majority of NF tumours, while less intense WE-14 immunoreactivity was detected in a subpopulation of NF tumour cells. Approximately half of the functioning pituitary tumours expressed CgA immunoreactivity. Six of nine ACTH-secreting tumours displayed CgA and IP immunostaining; four of these tumours displayed PST immunoreactivity. WE-14 immunoreactivity was detected in one corticotroph tumour. Three of six growth hormone (GH) secreting tumours displayed CgA immunostaining, two exhibited PST and IP, and one exhibited WE-14 immunoreactivity. Clusters of WE-14 immunopositive cells were detected in one GH tumour. One of seven prolactinomas exhibited weak CgA immunostaining, while weak IP and WE-14 immunostaining was detected in an additional tumour. No PST immunostaining was detected in prolactinomas. Therefore CgA is a valuable marker of NF pituitary tumours, however it is a more sporadic marker of functioning adenomas. In general, the cellular pattern and intensities of CgA, PST and IP immunoreactivity were comparable in the majority of pituitary adenomas. In contrast, WE-14 immunostaining was observed in a subpopulation of tumour cells. The pathophysiological significance of the proteolysis of CgA to generate bioactive peptides in both NF and functioning pituitary adenomas remains to be established.     

Double Pituitary Adenomas: Six Surgical Cases

While double pituitary adenomas have been found in approximately 1% of autopsy pituitaries, those in surgically resected material have been only rarely reported. We report herein 6 cases of double pituitary adenomas, which consisted of two histologically and/or immunohistochemically different areas among approximately 450 surgical specimens. Five out of 6 patients were men and the age was ranged between 18 and 61 years old. All these 6 patients presented acromegaly or acrogigantism and hyperprolactinemia was noted in 3 patients. In 2 patients (cases 1 and 2) the two adenomas belonged to different adenoma groups (GH-PRL-TSH group and FSH/LH group), while in the remaining 4 patients (cases 3–6) the two adenomas belonged to the same group (GH-PRL-TSH group). Thus, in all patients at least one of the two adenomas was GH-producing adenoma. Reasons for a high incidence of GH-producing adenomas in surgically resected double pituitary adenomas may include the presence of a variety of histologic subtypes among GH-producing adenomas and the advantage of cytokeratin immunostaining to distinguish these subtypes. In regard to pathogenesis of double pituitary adenomas, adenomas in cases 1 and 2 may be of multicentric occurrence, while those in cases 3–6 may occur through different clonal proliferation within originally one adenoma, resulting in diverse phenotypic expressions. Since there were patients with familial MEN 1 (case 2) and familial pituitary adenoma unrelated MEN 1 (case 3), genetic background should be also considered. Double pituitary adenomas in surgically resected material may not be so infrequent. Further molecular analysis will provide new insights into understanding the pathogenesis of pituitary adenomas and their mechanisms of multidirectional phenotypic diffrentiation.     

MAP-2 Expression in the Human Adenohypophysis and in Pituitary Adenomas. An Immunohistochemical Study

MAP-2, a well characterized member of the microtubule associated protein (MAP) family, binds to and stabilizes microtubules and is involved in cell proliferation as well as neuronal differentiation. The aim of the present work was to study MAP-2 expression in human adenohypophyses and pituitary adenomas. To our knowledge, data regarding MAP-2 expression in human pituitaries has not been reported to date. For immunohistochemistry, the streptavidin-biotin-peroxidase complex method was used. Nine non-tumorous adenohypophyses and 77 adenomas (GH-, PRL-, ACTH-, TSH-, FSH/LH- and/or alpha subunit- producing or immunonegative tumors) were investigated. The results show that MAP-2 is expressed in the cytoplasm of non-tumorous adenohypophysial cells as well as of various pituitary adenoma types. No significant correlation was found between MAP-2 expression and gender, patient age, mitotic activity, MIB-1 labelling indices, hormone immunoprofile, and endocrine status, ie. hormonal activity or lack thereof. Thus MAP-2 expression cannot be used to estimate cell proliferation rate, growth potential, endocrine activity or biologic behaviour of an adenoma. Immunopositivity appeared to be stronger in the cytoplasm of adenoma cells than in that of non-tumorous adenohypophysial cells, implying that the adenoma cells contain larger quantities of MAP-2. It can be concluded that the functional activity of MAP-2 is not associated with the manufacture of any specific adenohypophysial hormone(s) and is not limited to one specific cell type.     

Invasive Pituitary Adenomas: Significance of Proliferation Parameters

Although most pituitary adenomas behave in a purely benign fashion, microscopic invasion of the subjacent dura is very common, and clinically overt infiltration of the surrounding dura and bone is apparent at intraoperative inspection in about one third of cases. The factors governing invasive behavior remain unknown but are believed to be separate from those regulating cell proliferation. Histological features alone do not distinguish between benign, invasive, and malignant tumors of adenohypophyseal origin. Multiple attempts have been made to identify prognostic markers of aggressive behavior among these tumors. They include cytogenetic analysis of putative tumor suppressor genes or proto-oncogenes as well as immunohistochemical detection of cell-cycle specific antigens. At present, however, these analyses can neither distinguish the indolent pituitary adenoma from one that will pursue an invasive course, nor reliably predict the prognosis in individual patients.     

Localization of Inhibin/Activin Subunits in Normal Pituitary and in Pituitary Adenomas

The localization of inhibin/activin (I/A) subunits was investigated in human normal adenohypophysial cells and in 87 pituitary adenomas of different types, using immunohistochemistry. Monoclonal antibodies directed against , A and B subunits of I/A were employed. In normal pituitary, subunit of inhibin was detected only in FSH-positive gonadotrophs, while A subunit of I/A was expressed in FSH-positive gonadotrophs, GH-cells and in a few PRL-cells. B subunit was found in FSH-positive gonadotrophs, TSH-cells and a few LH-positive gonadotrophs. The three subunits of I/A were detected in the majority of nonfunctioning tumors, while functioning adenomas showed a significantly lower expression. This study shows that , A and B subunits of I/A are expressed by specific adenohypophysial cell types and that they are characteristically present in nonfunctioning adenomas. These results suggest that inhibins and activins may play a role in the local regulation of pituitary hormonal secretion both in normal adenohypophysial cells and in pituitary adenomas.     

Medical Therapy of Gonadotropin-Producing and Nonfunctioning Pituitary Adenomas

Clinically nonfunctioning pituitary adenomas are one of the most common types of pituitary tumors. Unless they present with symptoms related to local mass effect, most tumors are detected incidentally when imaging studies are performed for other reasons. Although clinically nonfunctioning, most of these tumors have evidence, in vitro, of gonadotropin hormone or glycoprotein subunit production. The gonadotropins or their monomer submits rarely cause clinically identifiable effects. When these tumors present as macroadenomas, often with associated mass effect and hypopituitarism, primary therapy is neurosurgery. The role for medical therapy will be reviewed here.     

Gender-Related Differences in Growth Hormone-Releasing Pituitary Adenomas. A Clinicopathological Study

Background/Aims: Pituitary adenomas are the third most common primary intracranial neoplasm, after astrocytomas and meningiomas, and about 30% of them secrete growth hormone (GH). Other subtypes of pituitary tumors are characterized by well-known gender-related differences, not only in clinical presentation and other biological characteristics but also in surgical outcome. For GH-releasing pituitary adenomas, however, detailed data on gender differences of postsurgical treatment are not available. Patients and methods: The patient charts of a series of 18 patients with acromegaly who met strict immunohistochemical and electron microscopic criteria and who underwent surgical resection of their tumors between January 1990 and June 1999 were retrospectively reviewed. Results: There were eight women and ten men; the male-to-female-ratio was 1.3:1. The men and women were equal in age at surgery. Men demonstrated higher IGF-1 and smaller GH levels pre- and postoperatively, whereas the reduction in IGF-1 was more pronounced compared to women (58% vs. 27%). The overall outcome was better in women than in men. Mixed GH- and prolactin-secreting adenomas showed a worse outcome among all other histological subtypes. Mitose- and MIB-1 labeling index was increased in men compared to women. Conclusion: The clinical course and tumor biology of GH-releasing pituitary adenomas appear to differ in women and men. Men demonstrated a shorter preoperative duration of symptoms, larger and more invasive tumors, and a worse clinical outcome. These findings suggest that therapy for GH-releasing adenomas should be more aggressive in men than in women. The gender-related differences in GH-releasing pituitary adenomas appear to have a basis in different biologic behavior, which warrants further investigation.     

Medical Management of Growth Hormone-Secreting Pituitary Adenomas

The primary treatment of acromegaly remains transsphenoidal adenomectomy, yet the tissue overgrowth of acromegaly often progresses following surgery, and responds to radiotherapy only after significant delay. Persistently elevated serum growth hormone (GH) and insulin-like growth factor-I (IGF-I) concentrations can be normalized in about half of post-surgery acromegalics using the pharmacologic alternatives presently available, the dopamine agonists (DA) and somatostatin (SST) analogs. Cabergoline, the most efficacious DA, normalizes IGF-I in approximately 37% of patients, whereas the long-acting SST analogs, Octreotide LAR and Lanreotide SR, do so in 66%. Significant tumor shrinkage may be attained with SST analogs in particular, and when necessary, the primary medical treatment of acromegaly may be successfully addressed with this class of drugs. Greatly enhanced efficacy is expected from the GH receptor antagonist pegvisomant, which is nearing market availability and will enable the normalization of serum IGF-I in virtually all patients treated. We review here the pharmacologic treatments of excessive GH secretion.     

Pituitary Apoplexy in a Patient with Acute Myeloid Leukemia and Thrombocytopenia

We describe a 72-year-old woman with a history of acute myeloid leukemia who developed pituitary apoplexy associated with thrombocytopenia secondary to chemotherapy. She presented with new onset severe headache, nausea, vomiting and blurred vision. Initial physical examination was unremarkable. CT scan of the head was initially negative. Upon admission for further work up, She developed a high-grade fever, hypotension and obtundation. Subsequent physical examination revealed bitemporal visual fields defects and decreased visual acuity. Repeat imaging of head revealed a hemorrhagic pituitary mass compressing the optic chiasm. Laboratory results were compatible with the diagnosis of pan-hypopituitary syndrome. She received high dose steroids and was transferred for transnasal sphenoidotomy decompression surgery. The visual defects improved postoperatively. A literature review of Pituitary apoplexy is presented. Pituitary apoplexy secondary to thrombocytopenia has never been reported.     

Minor Tumour Shrinkage in Nonfunctioning Pituitary Adenomas by Long-Term Treatment with the Dopamine Agonist Cabergoline

Objective: The purpose of this study was to define safety and efficacy of medical therapy in the treatment of nonfunctioning pituitary tumours. Design: We studied thirteen patients with a clinically nonfunctioning pituitary macroadenoma for response to cabergoline treatment for 1 year. Twelve/13 patients were already operated and had residual or recurrent tumours. Methods: We determined the outcome of treatment by visual perimetry, computed tumour size measurement in MRI and hormonal response (changes in pituitary function, reduction of -subunit). Results: Seven/13 patients on cabergoline had a tumour shrinkage above 10% of the initial tumour volume. In 4 patients, this tumour shrinkage was correlated to an increasing distance of the tumour to the optic chiasm. Only 2/9 patients with visual field defects before therapy showed improvements in visual acuity under cabergoline. No significant side effects of the therapeutical regimens were observed. Neither LH and/or FSH expression in the tumour cells nor the reduction of the -subunit serum levels by medical therapy was correlated to tumour shrinkage. Conclusion: Given that these patients had advanced disease which makes it difficult to find significant therapeutic effects, medical therapy with potent dopamine agonists such as cabergoline may evolve as a novel therapeutic option in a subgroup of patients with clinically nonfunctioning tumours declining operation and radiotherapy.     

Pituitary Apoplexy: A Review of Clinical Presentation, Management and Outcome in 45 Cases

Objective: To review clinical presentation, management and outcomes following different therapies in patients with pituitary apoplexy. Methods: Retrospective analysis of case-records of patients with classical pituitary apoplexy treated in our hospitals between 1983–2004. Results: Forty-five patients (28 men; mean age 49 years, range 16–72 years) were identified. Only 8 (18%) were known to have pituitary adenomas at presentation. Thirty-four (81%) patients had hypopituitarism at presentation. CT and MRI identified pituitary apoplexy in 28% and 91% cases, respectively. Twenty-seven (60%) patients underwent surgical decompression, whilst 18 (40%) were managed conservatively. Median time from presentation to surgery was 6 days (range 1–121 days). Patients with visual field defects were more likely than those without these signs to be managed surgically (p = 0.01). Complete or near-complete resolution occurred in 93% (13/14), 94% (15/16) and 93% (13/14) of the surgically treated patients with reduced visual acuity, visual field deficit and ocular palsy, respectively. All patients with reduced visual acuity (4/4), visual field deficit (4/4) and ocular palsy (8/8) in the conservative group had complete or near-complete recovery. Only 5 (19%) patients in the surgical group and 2 (11%) in the conservative group had normal pituitary function at follow up. One (4%) patient in the surgical group and 4 (22%) in the conservative group had a recurrence of pituitary adenoma. Conclusions: This large series suggests that the patients with classical pituitary apoplexy, who are without neuro-ophthalmic signs or exhibit mild and non-progressive signs, can be managed conservatively in the acute stage.     

Distribution and Regulation of Proconvertases PC1 and PC2 in Human Pituitary Adenomas

Pituitary adenomas are members of the family of neuroendocrine cells and tumors which have secretory granules containing chromogranins/secretogranins and other proteins. Pituitary adenomas express the neuroendocrine specific proconvertases PC1 (also known as PC3) and PC2, which are important for the proteolytic processing of chromogranins/secretogranins molecules. We examined the distribution of PC1 and PC2 in primary cultures of 20 pituitary adenomas and analyzed the regulation of the proconvertase mRNAs and proteins by various secretagogues including hypothalamic hormones and phorbol ester to determine the role of PC1 and PC2 in CgA processing in pituitary adenomas. Although PC2 was present in all adenomas, there was a differential distribution of PC1 with PRL adenomas expressing lower levels of PC1 compared to other adenoma types by RT-PCR analysis, in situ hybridization and immunostaining. Treatment of primary cultures of pituitary adenomas with phorbol 12-myristrate 13-acetate (PMA) resulted in an increase in pancreastatin (PST) secretion in most pituitary adenomas and increased PC1 mRNA and protein expression in gonadotroph adenomas, but not in other types of adenomas. Analysis of a human pituitary adenoma cell line, immortalized by recombinant defective adenovirus (HP75), which expressed chromogranin A, FSH, PC1 and PC2 showed that PST was secreted by these immortalized cells. Treatment with TGF1 resulted in an increase in PST secretion and in PC1 mRNA and protein. These results indicate that a) there is a differential distribution of PC1 in human pituitary adenomas with PRL adenomas expressing very little PC1 mRNA and protein and b) that PC1 expression in gonadotropin hormone-producing adenomas is regulated by PMA and TGF1. These findings support the observation that chromogranin A is a substrate for the endoproteinase PC1 in human pituitary adenoma cells.     

Correlation of Bcl-2 and Bax with Apoptosis in Human Pituitary Adenomas

Bcl-2 oncogene and Bax gene play an important role in regulating apoptosis. In the present study, the expression of bcl-2 and bax was investigated and correlated with apoptosis in a series of 81 pituitary adenomas. Bcl-2 and bax proteins were localized by immunohistochemistry and the histoscore (HSC) was assessed by multiplying the immunohistostaining grade (1 to 4) by the staining intensity grade (1 to 3). According to bcl-2/bax HSC the tumors were separated in group A when > or = 1 and group B when < 1. The apoptotic labeling index (ALI) was accessed by the in situ end-labeling (ISEL) technique. Bcl-2 protein was equally detected in functioning and nonfunctioning adenomas with statistically significant higher HSC in nonfunctioning tumors (P < 0.03). Bax protein was immunopositive in the substantial majority of adenomas with significantly higher HSC in functioning as compared to nonfunctioning adenomas (P < 0.0009). The ALI was significantly higher in functioning adenomas as compared to nonfunctioning adenomas (P < 0.04). In addition, ALI was significantly higher in group B than in group A (P < 0.004) and it was correlated with bax HSC (P < 0.004). Finally, the group B of bcl-2/bax significantly predominated in nonfunctioning tumors (P < 0.0009) and in microadenomas (P = 0.05), as compared with functioning adenomas and macroadenomas respectively. In conclusion, our findings suggest that bcl-2 and bax molecules play a role in the regulation of apoptotic mechanisms in pituitary adenomas.     

Pituitary Lymphoma: A Case Report and Literature Review

We report the case of a B-cell type pituitary lymphoma in a 65 year-old male immunocompetent patient who presented with hypogonadotropic hypogonadism and central hypothyroidism and subsequently developed pulmonary lymphoma. Only three cases of pituitary lymphoma have been previously reported, one in a patient with acquired immunodeficiency syndrome, one case of T-cell lymphoma reported in the Japanese literature, and one case of B-cell lymphoma. The previously reported immunocompetent patients presented with signs and symptoms of optic chiasm compression as contrasted to our patients endocrinologic presentation. B-cell lymphoma of the pituitary gland is a exceedingly rare though distinct clinical entity.     

Immunohistochemical Expression of Matrix Metalloproteinase-7 in Human Colorectal Adenomas Using Specified Automated Cellular Image Analysis System: A Clinicopathological Study

Background/Aim:

To evaluate the immunohistochemical expression of matrix metalloproteinase-7 (MMP-7) in colorectal adenomas, and to correlate this expression with different clinicopathological parameters.

Patients and Methods:

The study was retrospectively designed. Thirty three paraffin blocks from patients with colorectal adenoma and 20 samples of non-tumerous colonic tissue taken as control group were included in the study. MMP-7 expression was assessed by immunohistochemistry method. The scoring of immunohistochemical staining was conducted utilizing a specified automated cellular image analysis system (Digimizer).

Results:

The frequency of positive immunohistochemical expression of MMP-7 was significantly higher in adenoma than control group (45.45% versus 10%) (P value < 0.001). Strong MMP-7 staining was mainly seen in adenoma cases (30.30%) in comparison with control (0%) the difference is significant (P < 0.001). The three digital parameters of MMP-7 immunohistochemical expression (Area (A), Number of objects (N), and intensity (I)) were significantly higher in adenoma than control. Mean (A and I) of MMP-7 showed a significant correlation with large sized adenoma (≥ 1cm) (P < 0.05), also a significant positive correlation of the three digital parameters (A, N, and I) of MMP-7 expression with villous configuration and severe dysplasia in colorectal adenoma had been identified (P < 0.05).

Conclusion:

MMP-7 plays an important role in the growth and malignant conversion of colorectal adenomas as it is more likely to be expressed in advanced colorectal adenomatous polyps with large size, severe dysplasia and villous histology. The use of automated cellular image analysis system (Digmizer) to quantify immunohistochemical staining yields more consistent assay results, converts semi-quantitative assay to a truly quantitative assay, and improves assay objectivity and reproducibility.     

A Case of Pituitary Adenoma Associated with McCune-Albright Syndrome

A 11-year-old boy presented with right temporal hemianopsia and was evaluated of a possible pituitary adenoma. At the age of six, he underwent surgery for facial deformities due to fibrous dysplasia. On admission, he had acromegalic features, was 170 cm tall, weighing 66 kg. The left side of his face was slightly deformed, and a café-au-lait spot was found on his right face. Endocrinologic examination revealed elevated basal level of serum GH (103.6 ng/ml, normal <3 ng/ml) and PRL (259.1 ng/ml, normal <30 ng/ml). Other endocrine functions were normal. CT showed hyperostosis of the right frontal, occipital, sphenoidal and maxillary bones. Magnetic resonance imaging (MRI) revealed a pituitary macroadenoma with intraadenomatous cyst. On the basis of physical, endocrinologic and neuroradiologic examination, our diagnosis was pituitary adenoma with McCune-Albright syndrome. Surgery was performed by subfrontal approach. By light microscopy, the pituitary tumor represented a typical acidophilic adenoma. Immunoreactivity for GH and PRL were evident in most of the adenoma cells. Double immunostaining for GH and PRL demonstrated the co-existence of the two hormones in a few adenoma cells. However the majority of cells expressed only one hormone. After surgery the right temporal hemianopsia improved. Postsurgical endocrinologic examination revealed reduction in basal serum GH and PRL levels. Administration of bromocriptine decreased blood PRL levels but it had a limited action on GH hypersecretion.