Estrogen receptors in prolactinomas: a clinico-pathological study

Clinical Implications of the New WHO Classification 2017 for Pituitary Tumors

According to the WHO classification 2017 of Pituitary Tumors adenomas are classified not only by structure and immunostaining for pituitary hormones but also by expression of the pituitary transcription factors Pit-1, T-pit and SF-1. By these factors, three cell lineages can be identified: Pit-1 for the GH-, Prolactin- and TSH-cell lineage, T-pit for the ACTH-cell lineage, and SF-1 for the gonadotrophic cell lineage. By this principle, all GH and/or Prolactin producing and all TSH producing adenomas must be positive for Pit-1, all corticotrophic adenomas for T-pit, and all gonadotrophic for SF-1. In adenomas without expression of pituitary hormones immunostainings for the transcription factors have to be examined. If these are also negative the criteria for an endocrine inactive null cell adenoma are fulfilled. If one transcription factor is positive the corresponding cell lineage indicates a potential hormonal activity of the adenoma. So Pit-1 expressing hormone-negative adenomas can account for acromegaly, hyperprolactinemia, or TSH hyperfunction. T-pit positive hormone negative adenomas can induce Cushing's disease, and SF-1 positive hormone negative tumors indicate gonadotrophic adenomas. Instead of the deleted atypical adenoma of the WHO classification of 2004 now (WHO classification 2017) criteria exist for the identification of aggressive adenomas with a conceivably worse prognosis. Some adenoma subtypes are described as aggressive "per se" without necessity of increased morphological signs of proliferation. All other adenoma subtypes must also be designated as aggressive if they show signs of increased proliferation (mitoses, Ki-67 index>3-5%, clinically rapid tumor growth) and invasion. By these criteria about one third of pituitary adenoma belong to the group of aggressive adenomas with potentially worse prognosis. The very rare pituitary carcinoma (0.1 % of pituitary tumors) is defined only by metastases. Many of them develop after several recurrences of Prolactin or ACTH secreting adenomas. The correlation of clinical findings and histological classification of pituitary adenomas is very important since every discrepancy has to be discussed between clinicians and pathologists. Based on data of the German Registry of Pituitary Tumors a table for examinations of correlations is shown in this review.

Galectin-3 and Estrogen Receptor Alpha as Prognostic Markers in Prolactinoma: Preliminary Results From a Pilot Study

INTRODUCTION

Prolactin-secreting pituitary tumors (PRL-omas) are generally benign neoplasia. However, a percentage of cases show aggressive behavior. Prognostic markers may allow for the identification of aggressive cases. In this study, we investigated the prognostic role of galectin-3 and the estrogen receptor alpha (ERα), as predictive biomarkers of aggressiveness and poor prognosis.

PATIENTS AND METHODS

A mono-centric and retrospective study was conducted on consecutive cases of PRL-omas that underwent first line treatment with surgery and were followed-up for at least five years. The immunohistochemical expression of ERα and galectin-3 was investigated in each case.

RESULTS

36 patients were enrolled. Galectin-3 resulted positive in 11 patients (30.6%). The median expression of ERα was 85% (IQR: 37). Among the group of 21 patients who underwent radical surgery (58.3%), recurrence occurred in 12 cases (33.3%). 27 patients were treated post-surgery with a dopamine agonist (DA) (12 for recurrence and 22 for a history of partial surgery). 13 patients (48.1%) were responsive to DA. Six of 11 cases positive for galactin-3 underwent partial surgery (54.5%, p<0.001). Recurrence occurred in all five cases that underwent radical surgery, which were also positive for galectin-3 (p=0.03). Galectin-3 resulted positive in 9 patients resistant to DA treatment (81.1%, p=0.01). ERα expression was lower in tumors positive for galectin-3 (p<0.001), with mitotic activity (p=0.012), with higher Ki67 Li (p<0.001), and in males with post-surgical recurrence (p<0.001).

CONCLUSION

Galectin-3 and ERα play as markers of aggressiveness and prognosis in PRL-omas and may be tested to identify the aggressive forms of the disease.

Pathology of prolactinomas: any predictive value?

Lactotroph adenomas, also called prolactinomas and prolactin-secreting adenomas, constitute nearly 80% of functioning pituitary tumors and about 30-50% of all adenomas in the clinical practice. Lactotroph adenomas occur in the general population at a prevalence of 45/100,000, are more common in women, but also involve men and children of both sexes. Most lactotroph adenomas are microadenomas occurring in reproductive-age women who present with oligo/amenorrhea, galactorrhea, and infertility. In men and elderly women, lactotroph adenomas are usually macroadenomas and are most commonly associated with symptoms of a tumoral mass, including headaches, neurologic defects, and visual loss. Although clinical and laboratory features may differ depending on patient's gender and age, the histopathology of the tumors is similar. Lactotroph adenomas are histologically classified into three subtypes: the common sparsely granulated lactotroph adenoma, and the rare densely granulated lactotroph adenoma and acidophilic stem cell adenoma. We will review the main pathological features of the lactotroph adenomas and some of their characteristics that may predict biological behavior and responsiveness to treatment.

[Pituitary lactotroph adenomas resistant to dopamine agonist treatment: histological and immunohistochemical characteristics]

OBJECTIVE

To present the histological and immunohistochemical characteristics of pituitary lactotroph adenomas (PLAs) resistant to dopamine agonist treatment.

SUBJECT AND METHODS

The investigators examined paraffin-embedded blocks and histological sections obtained from 19 patients (13 women, 6 men), whose median age was 29 (19, 38) years, after surgical treatment (adenomectomy) for PLAs resistant to dopamine agonist treatment. Immunohistological examination was performed using antibodies against prolactin (PRL), growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), type 2 dopamine receptors (DR₂), estrogen receptors-α (ERα), the proliferation marker Ki-67, and the endothelial cell marker CD34.

RESULTS

The expression of PRL by adenoma cells was revealed in all the patients. The coexpression of PRL and GH without clinical and laboratory signs of acromegaly was established in 3 cases. No expression of TSH, ACTH, LH, or FSH was revealed in any cases. Positive immunoreaction using antibodies against DR₂ and ERα was detected in 8 and 6 cases, respectively. No expression of any of the studied receptors was found in 6 patients. Ki-67 was more than 3% in 3 patients and higher in patients with supra- or retrosellar growth. There was a positive correlation between the serum level of Ki-67 and that of PRL at the onset of the disease. There were 37 (25, 85) adenoma vessels, as measured by CD34 immunoexpression. It was ascertained that the patients with parasellar adenoma had more tumor vessels than those without parasellar growth of adenoma and that with the latter invading the cavernous vessels, the number of vessels was statistically significantly more.

CONCLUSION

PLAs resistant to dopamine agonists in addition to PRL (100%) can express GH in 16% of cases are characterized by the immunoexpression of DR₂ (42%) and ERα (32%), a low proliferative activity, increased angiogenesis in the adenomas with parasellar growth and invasion into the cavernous sinus.

THE EFFECT OF RALOXIFENE ON SERUM PROLACTIN LEVEL IN PATIENTS WITH PROLACTINOMA

Objective: To evaluate the effect of raloxifene on prolactin (PRL) levels in addition to dopamine agonist (DA) therapy in patients with prolactinoma. Methods: We conducted a retrospective chart review of 14 patients with prolactinoma on stable dose of DA for 6 months who received raloxifene 60 mg daily, as PRL could not be normalized despite being on fairly high doses of DA. Patients were informed that raloxifene is not approved by the Food and Drug Administration for prolactinoma treatment. PRL level was measured at 1 to 6 months after starting raloxifene and at 1 to 3 months following its discontinuation. Raloxifene was stopped in 8 out of 14 patients after 2 (1 to 6) months of treatment as the absolute change in PRL level was felt to be small. Results: The median age and female/male sex ratios were 50 years (range 18 to 63 years), 6/8 respectively. The baseline DA dose was 3 mg/week (0.5 to 7 mg/week) for cabergoline and 15 mg/day for bromocriptine. Ten patients had an absolute and percentage decrease in PRL of 8.3 ng/mL (1.5 to 54.2 ng/mL) and 25.9% (8 to 55%) from baseline, respectively, after 1 to 6 months on raloxifene treatment. Among 10 patients with a decrease in PRL level, 2 (20%) achieved PRL normalization. Two patients had no change in PRL and two patients had an increase in PRL level by 22.8 ng/mL and 8.8 ng/mL (47% and 23.6%), respectively. Conclusion: Raloxifene was associated with a 25.9% (8 to 55%) decrease in PRL level in 10/14 (71%) patients with prolactinoma who were on stable doses of DA including 2 patients (14%) who achieved normoprolactinemia. Abbreviations: CV = coefficient of variation; DA = dopamine agonist; FSH = follicule-stimulating hormone; LH = luteinizing hormone; PRL = prolactin; PTTG = pituitary tumor transforming gene.

Current indications for the surgical treatment of prolactinomas

The purpose of this study was to examine the current indications for transsphenoidal surgery in the prolactinoma patient population, and to determine the outcomes of patients who undergo such operations. Transsphenoidal surgery may be indicated in prolactinoma patients who are resistant and/or intolerant to dopamine agonist (DA) therapy. We performed a retrospective review of the medical records of prolactinoma patients over a 6 year period (April 2008 to April 2014) at a large volume academic center. The median follow-up time was 12.0 months (range: 3-69). All patients who were included in the study (n=66) were treated with DA therapy and subsequently underwent an endonasal transsphenoidal operation. Of the 66 patients, 44 were women (mean age 34.2 years) and 22 were men (mean 41.7 years). There were 29 (43.9%) intolerant patients and 29 (43.9%) resistant patients. Postoperatively, 18 intolerant patients (66.7%) had normalized prolactin levels without the need for DA therapy, and five (17.2%) required DA to normalize their prolactin levels (p=0.02). Six patients (20.6%) had persistently elevated prolactin levels but were no longer receiving DA treatment (p<0.001). Postoperatively, 10 resistant patients (35.7%) had normal prolactin levels without DA therapy, and seven patients (25%) were treated with DA therapy to normalize their prolactin levels (p=0.22). Eight patients (28.6%) had supraphysiologic prolactin levels but were no longer taking a DA (p<0.001). Three patients (10.7%) were hyperprolactinemic, despite postoperative treatment with DA (p<0.001). After an appropriate treatment interval with multiple DA, radiographic follow-up, and careful clinical evaluation, prolactinoma patients can be offered surgery as an effective therapeutic option.

Expression of estrogen receptor alpha is associated with prolactin pituitary tumor prognosis and supports the sex-related difference in tumor growth

CONTEXT

A sex difference in the progression of prolactin (PRL) tumors has been disputed for years.

OBJECTIVE

To compare tumor characteristics and postoperative clinical course between men and women, and correlate data with estrogen receptor alpha (ERα (ESR1)) expression status.

DESIGN, PATIENTS, AND METHODS

Eighty-nine patients (59 women and 30 men) operated on for a prolactinoma and followed for at least 5 years were selected. Tumors were classified into five grades according to their size, invasion, and proliferation characteristics. The ERα expression was detected by immunohistochemistry and a score (0-12) calculated as the product of the percentage of positive nuclei and the staining intensity.

RESULTS

We found a significant preponderance of high-grade tumors among men and a lower surgical cure rate in men (23%) than in women (71%). Patients resistant to medical treatment were mainly men (7/8), six of whom showed tumor progression despite postoperative medical treatment, which led to multiple therapies and eventually death in three. The median score for ERα expression was 1 in men (range, 0-8) and 8 in women (range, 0-12) (P<0.0001). The expression of ERα was inversely correlated with tumor size (r=-0.59; P<0.0001) and proliferative activity. All dopamine agonist-resistant tumors and all grade 2b (invasive and proliferative) tumors (from ten men and four women) were characterized by low ERα expression.

CONCLUSIONS

PRL tumors in men are characterized by lower ERα expression, which is related to higher tumor grades, resistance to treatment, and an overall worse prognosis.

Aromatase cytochrome P450 enzyme expression in prolactinomas and its relationship to tumor behavior

The aim of the study was to evaluate the presence of aromatase cytochrome P450 enzyme (P450AROM) expression in normal pituitary tissues and tumor tissues of patients with prolactinoma and to examine the impact of the P450AROM expression on clinical outcome. Twenty-six consecutive human pituitary tissue samples were obtained from autopsies performed at the Institute of Forensic Medicine. Sixty-four patients who had an adenomectomy between 2000 and 2009 after prolactinoma diagnosis with histologically confirmed pituitary tumor tissues were retrospectively included in this study. The slices from the pituitary tissues were subjected to immunohistochemical staining for evaluation of P450AROM and estrogen receptor beta (ER beta) subunit. Immunohistochemistry results were compared according to age, gender, remission rate, resistance and invasion status of the patients. Higher than normal P450AROM expression was found in the pituitary tissues of the patients with prolactinoma (p < 0.001). P450AROM intensity had no relation to resistance or remission in patients with prolactinoma (p = 0.44, p = 0.45, respectively). The subgroup analysis showed that compared to males without invasive adenoma, males with invasive adenoma had higher P450AROM expression (p = 0.048). ER beta was found to have an impact on resistance (p = 0.049). This study shows that P450AROM expression is present in the pituitary tissues of patients with prolactinoma and that this presence could be important in development and tumor behavior of prolactinomas.

Dopamine agonist-resistant prolactinomas

The authors' object in this paper was to review the definition, epidemiology, biology, resistance mechanisms, and treatment options for dopamine agonist-resistant prolactinomas (DARPs). Prolactinomas are relatively unique among primary brain tumors in that medical treatment alone using dopamine agonists carries a high probability of disease control or even radiographic and endocrine remission, and thus has replaced surgery as the first line of therapy. Unfortunately, slightly less than 10% of patients with prolactinomas do not experience normalization of their prolactin levels in response to dopamine agonists, and harbor tumors that are resistant to dopamine agonist therapy. A literature review underscores that in male patients these DARPs are more likely to be invasive macroadenomas than dopamine agonist-responsive prolactinomas and that they are also more angiogenic, more proliferative, and more likely to exhibit cellular atypia. Estrogen receptor antagonists and temozolomide are the most commonly applied medical therapies in cases in which resection and radiosurgery have not induced remission of the hyperprolactinemia. Dopamine agonist-resistant prolactinomas exhibit aggressive behavior and tend to be large, invasive, hyperangiogenic tumors with high mitotic indices, which makes their management via surgery, radiosurgery, or alternative medical therapies challenging, thus underscoring the need for novel medical therapies or treatment regimens that target these lesions.

A case of fugitive acromegaly, initially presented as invasive prolactinoma

Fugitive acromegaly is most commonly caused by pituitary acidophil stem cell adenomas, and is characterized by a relatively short clinical history, a large and locally invasive tumor, and relatively low hormonal activity. Here, we report an unusual case of fugitive acromegaly that initially presented as invasive prolactinoma. A 48-year-old man with a huge pituitary mass extending to the suprasellar area was referred to our hospital in December 2007. He had undergone transsphenoidal surgery in November 1999 because of a large invasive prolactinoma. The tumor had grown progressively, despite therapy with dopamine agonists. Subtle features of acromegaly were noted and serum IGF-1 levels were high (733 ng/ml). An oral glucose tolerance test revealed that basal and nadir levels of growth hormone (GH) were 1.56 and 1 ng/ml, respectively. As a therapeutic trial, long-acting octreotide (20 mg IM, monthly) was added, and the tumor size markedly reduced within 6 months on magnetic resonance imaging examination. Immunohistochemical staining of the tumor tissue obtained at the surgery in 1999 showed positive staining for GH and prolactin (PRL). Double immunofluorescence staining showed a mixed positivity for GH and PRL in the majority of tumor cells; however, the two hormones colocalized in a minority of tumor cells, indicating that the tumor was composed of three different cell types (GH, PRL, and GH/PRL). The diagnosis of fugitive acromegaly was initially overlooked in this patient because of normal serum GH levels and a lack of acromegalic features, although histological evidence for GH production was present. IGF-1 determinations would be helpful for the diagnosis of fugitive acromegaly.

Future treatment strategies of aggressive pituitary tumors

While surgery remains the first-line treatment of most aggressive pituitary adenomas, medical therapy is important as second-line or adjunctive therapy in a large proportion of patients. Dopamine agonists (DAs) are the best treatment for prolactinomas, but when DAs are not tolerated, new somatostatin receptor subtype 5 (SSTR(5)) inhibitors may offer an alternative in the future. Unfortunately, these are unlikely to be effective in DA-resistant prolactinomas. In acromegaly, the existing somatostatin analogs, octreotide and lanreotide, will remain the medical treatment of choice for the foreseeable future. There is an urgent need for medical therapies in Cushing's disease, and the SSTR(5) analogs could offer an effective treatment in a proportion of patients within the next few years. Finally, the medical management options for non-functioning pituitary adenomas are also very limited, and a new chimeric agent with activity towards dopamine receptors, SSTR(5) and SSTR(2) may help reduce adenoma recurrence in the future.

Molecular and trophic mechanisms of tumorigenesis

A significant proportion of pituitary macroadenomas, and by definition all microadenomas, regain trophic stability after an initial period of deregulated growth. Classical proto-oncogene activation and tumor suppressor mutation are rarely responsible, and no histologic or molecular markers reliably predict behavior. GNAS1 activation and the mutations associated with multiple endocrine neoplasia type 1 and Carney complex, aryl hydrocarbon receptor interacting protein gene mutations, and a narrowing region of chromosome 11q13 in familial isolated acromegaly together account for such a small proportion of pituitary adenomas that the pituitary adenoma pathogenic epiphany is surely yet to come.

Temozolomide in the treatment of an invasive prolactinoma resistant to dopamine agonists

Prolactinomas are common tumors of the anterior pituitary gland. While conventional therapies, including dopamine agonists, transsphenoidal surgery and radiotherapy, are usually effective in controlling tumor growth, some patients develop treatment-resistant tumors. In this report, we describe a patient with an invasive prolactinoma resistant to conventional therapy that responded to the administration of the alkylating agent, temozolomide.

Reversal of hypogonadotropic hypogonadism with tamoxifen in a patient with hyperprolactinemia resistant to dopamine agonists

OBJECTIVE

To determine the response to tamoxifen in a woman with hypogonadotropic hypogonadism induced by hyperprolactinemia resistant to dopamine agonist drugs.

DESIGN

Case report.

SETTING

Academic fertility center.

PATIENT(S)

A young woman with persistent amenorrhea, symptomatic hypogonadotropic hypogonadism, and hyperprolactinemia.

INTERVENTION(S)

Tamoxifen was administered in addition to bromocriptine.

MAIN OUTCOME MEASURE(S)

Measurements of follicle-stimulating hormone, estradiol, prolactin, and progesterone.

RESULT(S)

Recovery of gonadal-hypothalamic-pituitary axis.

CONCLUSION(S)

Tamoxifen can revert the effects of chronic hypogonadotropic hypogonadism induced by hyperprolactinemia resistant to dopamine agonists.

Effects of estrogen and tamoxifen on the ultrastructural characteristics of female rat prolactin cells as evaluated by immunogold technique

Estrogens and antiestrogens are known to have effects on prolactin (PRL)-producing cells in the anterior pituitary. This study was planned to investigate the effects of estrogen and tamoxifen at immunohistochemical and immunoelectron microscopic levels on PRL cells of female rat pituitary. Animals were divided into three groups of eight adult female rats each. The first group was the control group. 200-microg/day of estrogen was administered subcutaneously for 11 weeks to 16 rats. Tamoxifen was administered to eight of them for the last 15 days. In diethylstilbestrol (DES)-induced group, serum PRL levels and pituitary weights were found to be elevated when compared with the control group. In the DES plus tamoxifen group the readings were close to that of the control group. PRL-positive cells were enlarged and strongly immunostained in DES-induced group when assessed by light microscopy. Tamoxifen prevented this effect. At the ultrastructural level, in the tamoxifen treated group, PRL-producing cells contained both immunopositive and immunonegative secretory granules. Numerous PRL-producing cells exhibited progressive morphological changes in the nuclei compatible with the apoptotic process. The results of this study indicate that tamoxifen prevents not only the proliferative effect of estrogen but also inhibits the secretion mechanism of the cells.

Immunohistochemical detection of estrogen receptor alpha in pituitary adenomas and its correlation with cellular replication

With the aim of evaluating the relationship between pituitary tumorigenesis and the presence of estrogen receptor-alpha (ERalpha) by immunohistochemistry (IH) and their relevance to patients' clinical presentation, hormonal phenotypes of adenomas, preoperative neuroimaging findings, and the index of cellular replication MIB-1, a study was conducted with material from 91 women and 67 men with pituitary adenomas. The patients had acromegaly (29.7%), Cushing's disease (14.6%), hyperprolactinemic syndrome (20.9%), and clinically nonfunctioning tumors (34.8%). Of the patients, 14.6% had microadenomas, 52.5% had macroadenomas with or without suprasellar growth, 28.5% had invasive macroadenomas and in 4.4% the adenoma was not visualized. IH showed that 43 were positive for growth hormone (GH), 16 for corticotropin (ACTH), 18 for prolactin (PRL), 18 for PRL+GH, 6 for luteinizing hormone (LH) and follicle-stimulating hormone (FSH), 15 had a plurihormonal reaction, and 42 had nonfunctioning adenomas. The presence of ERalpha was positive in 9/158 adenomas with a median value for the percentage of labeled cells of 42.89%, and in 6/16 controls (autopsy samples) with a median value for the percentage of labeled cells of 0.024%. ERalpha was significantly more prevalent in controls than in patients with adenomas (37.5 versus 5.7%; p = 0.001); however, the mean ERalpha concentration in adenomas was significantly greater than in controls (42.89 versus 0.024%; p < 0.001). No significant difference in the concentration of ERalpha was found across the clinical presentations, hormonal phenotypes or findings of preoperative CT. Among the ERalpha-positive adenomas, ERalpha values were significantly greater in invasive macroadenomas (80%) than in microadenomas (3.33%). MIB-1 values did not differ significantly between ERalpha-positive and -negative adenomas, nor did the correlation between ERalpha values and the MIB-1 index attain significance in the total sample, even when only ERalpha-positive adenomas and positive MIB-1 indexes were considered. It was concluded that, when present in pituitary tumors, ERalpha exhibits a high concentration, and is more common in nonfunctioning and invasive adenomas, but absent in ACTH-secreting ones.

Molecular defects in the pathogenesis of pituitary tumours

The majority of pituitary adenomas are trophically stable and change relatively little in size over many years. A comparatively small proportion behave more aggressively and come to clinical attention through inappropriate hormone secretion or adverse effects on surrounding structures. True malignant behaviour with metastatic spread is very atypical. Pituitary adenomas that come to surgery are predominantly monoclonal in origin and roughly half are aneuploid, indicating either ongoing genetic instability or transition through a period of genetic instability at some time during their development. Few are associated with the classical mechanisms of tumour formation but it is generally believed that the majority harbour quantitative if not qualitative differences in molecular composition compared to the normal pituitary. Despite their prevalence and the ready availability of biopsy material, at the present time, the precise molecular pathogenesis of the majority of pituitary adenomas remains unclear. This review summarizes current thinking.