Posterior pituitary tumours: the spectrum of a unique entity. A clinical and histological study of a large case series

PURPOSE

In 2017, the WHO established that pituicytoma, granular cell tumour (GCT) and spindle cell oncocytoma (SCO) are posterior pituitary tumours (PPT). Recent data suggests that these tumours probably arise from the pituicytes and may constitute a spectrum of a unique histopathological entity. Our aim is to report the clinical findings and surgical outcomes of 16 patients with PPT. We also evaluated the tissue specimens available in light of current knowledge.

METHOD

Cross-sectional study with retrospective data.

RESULTS

PPT were 7 pituicytomas, 3 GCT and 6 SCO. Patients mean age was 55 years old and 75% were female. Basal hormonal study showed hyperprolactinemia (43.7%) and hypopituitarism (37.5%). There was no case of diabetes insipidus (DI). MRI showed sellar/suprasellar masses with mean size of 19.7mm. PPT was not suspected in any patient. Fifteen patients underwent surgery and complications were common: 20% had perioperative bleeding (one patient died because of a massive haemorrhage), 57.1% hypopituitarism, 35.7% permanent DI and 21.4% underwent a second surgery. Pathological findings shown positivity for thyroid transcription factor 1, vimentin and negativity for cytokeratin and chromogranin A in all specimens evaluated. S100 protein was positive in 88.8% of tumours. Ki67 was ≥ 3% in 66.6% and ranged from 4-7% in SCO.

CONCLUSION

PPT have similar histology, clinical features and are frequently misdiagnosed as nonfunctioning pituitary tumours. However, post-surgical complications including haemorrhage are common. A high clinical suspicion is needed to presume the diagnosis prior surgery and diminish the high morbidity of these tumours.

Xanthomatous hypophysitis

We present a 69-year-old woman who presented with chronic headaches and was found to have a pituitary mass on MRI, which was biopsied and said to be lymphocytic hypophysitis. The woman was placed on prednisone and followed with routine eye examinations. Two years later, the lesion gradually increased in size and the woman developed a decrease in peripheral vision in the right eye. An MRI showed abutment of the right optic nerve by the mass. A repeat endoscopic transsphenoidal biopsy/resection of the pituitary lesion was performed. Histopathological analysis of the specimen was consistent with diagnosis of xanthomatous hypophysitis (XH). XH is an inflammatory disorder of the pituitary gland characterized by an infiltration of lipid-laden histiocytes, also known as xanthoma cells. The mass was biopsied and a diagnosis of lymphocytic hypophysitis was made. The woman reported improved visual acuity and peripheral vision postoperatively. One year after the second resection, her visual symptoms worsened. Repeat MRI revealed expansion of the residual pituitary tissue. She was referred to the radiation oncology department for external beam radiation therapy and was placed on a maintenance dose of steroids. Since undergoing radiation therapy, her vision has improved slightly and her 3month MRI revealed stable lesion size. This woman illustrates a rare pituitary pathology presented with a literature review of published patients describing xanthomatous hypophysitis. A discussion of the clinical presentation, epidemiology, etiology, diagnosis, histology and treatment is provided.

Regulation of intestinal immune response by selective removal of the anterior, posterior, or entire pituitary gland in Trichinella spiralis infected golden hamsters

The influence of anterior pituitary hormones on the gastrointestinal tract of humans and animals has been previously reported. Hypophysectomy (HYPOX) in the rat causes atrophy of the intestinal mucosa, and reduction of gastric secretion and intestinal absorption, as well as increased susceptibility to bacterial and viral infections. However, to our knowledge, no findings have been published concerning the immune response following HYPOX during worm infection, particularly that which is caused by the nematode Trichinella spiralis. The aim of this work was to analyze the effects of total or partial HYPOX on colonization of T. spiralis in the intestinal lumen, together with duodenal and splenic cytokine expression. Our results indicate that 5 days post infection, only neurointermediate pituitary lobectomy (NIL) reduces the number of intestinally recovered T. spiralis larvae. Using semiquantitative inmunofluorescent laser confocal microscopy, we observed that the mean intensity of all tested Th1 cytokines was markedly diminished, even in the duodenum of infected controls. In contrast, a high level of expression of these cytokines was noted in the NIL infected hamsters. Likewise, a significant decrease in the fluorescence intensity of Th2 cytokines (with the exception of IL-4) was apparent in the duodenum of control and sham infected hamsters, compared to animals with NIL surgeries, which showed an increase in the expression of IL-5 and IL-13. Histology of duodenal mucosa from NIL hamsters showed an exacerbated inflammatory infiltrate located along the lamina propria, which was related to the presence of the parasite. We conclude that hormones from each pituitary lobe affect the gastrointestinal immune responses to T. spiralis through various mechanisms.

Granular cell tumor of the neurohypophysis: case report and review of the literature

A 54-year-old woman presented with a stalk mass that was discovered incidentally with mild visual fields defect. The mass was operated surgically by the fronto-temporal approach, and histology met the diagnosis of neurohypophesial granular cell tumor (GCT). After surgery, the patient suffered from an irreversible severe bi-temporal visual deficit and an irreversible hypopituitarism. We review the literature and discuss the clinical nature of GCTs, treatment options and outcome. In an effort to avoid the severe complications that may result from surgical removal of neurohypophesial GCT, we discuss also the possibility of choosing the conservative approach with close follow-up. The tumor's firm consistency, tendency to hemorrhage, involving the pituitary stalk and lack of dissection plane from basal brain structure render surgery difficult, and maximal resection often requires sacrificing the stalk. Moreover, small asymptomatic neurohypophysial GCTs are common findings, most probably benign tumors with slow growing nature. Hence, for a neurohypophesial tumor which is suspected to be a GCT, we offer to consider the alternative approach, with close clinical, visual field and radiological study follow up.

[Endoscopic, posterior transseptal pituitary surgery--learning curve of the surgical technique and equipment in 61 operations]

INTRODUCTION

The removal of hypophyseal tumor by transsphenoidal pituitary surgery using microsurgical instruments was first performed over 100 years ago. Operating techniques for this surgery are constantly being renewed, first by using a microscope and later on with the use of an endoscop. The authors provide an overview of the minimal invasive posterior transseptal-transsphenoidal aproach with the combined utilization of classical techniques with the assistance of the endoscop.

METHOD

Sixty-one patients (33 female, 28 male, 21-84 yrs) were treated for sellar region tumor resection using an endonasal transsphenoidal aproach with the help of an endoscope. Follow ups were performed within 2-21 months.

RESULTS

Total tumor resection was successful in 91.8%, and partial resection in 8.2% of the patients. The rate of complications using the endoscopic method was not higher compared to that of the classical microscopic method. There was no major bleeding in any of the cases. Adverse events such as minor epistaxis occurred in 4.9%, transitional diabetes insipidus in 6.5%, inraoperative CSF leak in 16.67%, postoperative CSF leak in 11.5% and meningitis in 8.2% of the patients. After the operation the pathological hormonal production stoped in all patients except in two patients who were acromegalic. However their GH level normalized and they did not require further treatment, the IGF-1 still remained high.

CONCLUSION

The success of the surgical treatment is based on both, the proficient pre- and postoperative endocrinological care, and the minimal invasive surgical technique. The endoscope was used partially or continuously during the operation for better visualization of the operation field in multiple angles (30 degrees, 45 degrees). It was useful in differentiating between normal and tumorous glandular tissue, and also offered an enhanced view of the intrasellar (via hydroscopy) and parasellar region. Moreover the endoscopic method is able to decrease the operating time, reduce blood loss. In different stages of the surgery, depending on the anatomical and pathological situation, switching back and forth from microscope to endoscope technique, gives us the benefit of a clearer view in each situation.

Pituicytomas: radiological findings, clinical behavior and surgical management

BACKGROUND

Pituicytomas are rare low-grade glial neoplasms originating in the neurohypophysis or infundibulum that appear as solid, noninfiltrative masses occupying the sella turcica, the suprasellar space or both. Due to their high tendency to bleed and the possible firmness and adhesion to surrounding structures, preoperative diagnosis of pituicytoma is a goal for the surgeon, but it is actually a challenge because of the absence of distinctive clinical or neuroradiological findings.

METHODS

We report the new cases of three patients who underwent transsphenoidal surgery for suspected pituitary adenomas, which were determined to be pituicytomas at histological and immunohistochemical analysis. We also review previously reported cases of pituicytoma in the literature.

RESULTS

To date, 51 cases of pituicytoma have been reported in addition to our own cases. The natural history and clinical characteristics of this rare tumor are outlined.

CONCLUSIONS

Macroscopic aspects are variable, and final diagnosis is made from the typical histological and immunohistochemical pattern. The therapy of choice is gross total surgical resection since subtotal removal can lead to local regrowth, but the time to recurrence is unpredictable and highly variable. The role of adjuvant therapy is currently undefined.

Surgical remission of pituitary adenomas confined to the neurohypophysis in Cushing's disease

CONTEXT

Partial or total removal of the pituitary cures 60-80% of patients with Cushing's disease (CD) in whom an adenoma cannot be identified at surgery. Many patients who fail complete or partial hypophysectomy are cured by sellar and parasellar irradiation.

DESIGN/PATIENTS

As part of a series of prospective studies of CD, we identified 12 patients (34.5 +/- 19.9 yr; 11 females; four children) with tumors located completely within the neurohypophysis among 730 patients undergoing surgery for CD.

SETTING

The study was conducted at a tertiary referral center at a clinical research hospital.

RESULTS

All 12 patients had clinical and biochemically defined CD. Tumor was visible at surgery in 11 patients; all 12 tumors were positive for ACTH by immunohistochemistry. Two tumors were excised at repeat surgery because of persistent hypercortisolism within 14 d of negative exploration of the adenohypophysis. There were no long-term complications. At follow-up of 71.9 +/- 34.2 months (range, 30-138 months), all patients are in remission of CD. Adult patients have had significant improvement in weight and body mass indices, with restoration of normal menses in all women. In the four pediatric patients, height, weight, and body mass indices have been restored toward normal by surgical remission of CD. Hypopituitarism or long-term neurohypophysial dysfunction has not occurred.

CONCLUSION

We report a new subset of patients with CD, ACTH-secreting adenomas that arise wholly within the posterior lobe of the pituitary gland. In cases of CD in which an adenoma is not identified in the adenohypophysis and in patients with persistent hypercortisolism after complete or partial excision of the anterior lobe, tumor within the neurohypophysis should be considered; selective adenomectomy of a neurohypophyseal, ACTH-secreting tumor can produce long-term remission.

Hypophysectomy and neurointermediate pituitary lobectomy reduce serum immunoglobulin M (IgM) and IgG and intestinal IgA responses to Salmonella enterica serovar Typhimurium infection in rats

The influence of anterior pituitary hormones on the gastrointestinal tract of humans and animals has been reported. Hypophysectomy (HYPOX) in the rat causes atrophy of the intestinal mucosa, reduction of gastric secretion and intestinal absorption, and increased susceptibility to infections. To our knowledge, there are no studies on the humoral immune response of the gut-associated lymphoid tissue after HYPOX. We have reported that decreased secretion of vasopressin and oxytocin due to neurointermediate pituitary lobectomy (NIL) diminishes humoral and cell-mediated immune responses. However, no data have been published on whether NIL can affect intestinal immune responses. We analyzed the effects of HYPOX and NIL on bacterial colonization of the intestinal lumen, Peyer's patches, and spleen as well as the serum immunoglobulin G (IgG) and IgM and specific intestinal IgA levels in response to Salmonella enterica serovar Typhimurium oral infection. Results showed the following: (i) Salmonella serovar Typhimurium was eliminated from the intestinal lumen at the same rate in rats that underwent a sham operation, HYPOX, and NIL; (ii) Salmonella serovar Typhimurium colonization of Peyer's patches and spleen was significantly higher in both HYPOX and NIL rats than in sham-operated rats; (iii) serum IgG and IgM and intestinal IgA against surface proteins of Salmonella serovar Typhimurium were significantly lower in HYPOX and NIL rats than in sham-operated rats; and (iv) compared to NIL rats, higher Peyer's patch and spleen bacterial colonization and decreased IgG, IgM, and IgA production were observed in HYPOX rats. We conclude that hormones from each pituitary lobe affect the systemic and gastrointestinal humoral immune responses through different mechanisms.

Intracranial retrograde dissemination in filum terminale myxopapillary ependymomas

Myxopapillary ependymomas (ME) are considered benign tumours (WHO grade I) of the central nervous system with long term survival rates and a tendency to local recurrence. However an aggressive course has occasionally been described, leading to CSF dissemination and even systemic metastases. We describe the case of a 23-year-old man diagnosed with intracranial subarachnoid dissemination of a filum terminale ME three years after the initial diagnosis. We have performed a careful review of the literature on CSF dissemination in ME and finally propose treatment of these cases.

Crush cytology of pituicytoma

The crush cytology of a pituicytoma is reported. The lesion was resected from a 54-yr-old man with a 7-mo history of headache. The intraoperative crush smears revealed plump spindle cells with elongated, nonwavy nuclei, and moderate, finely granular cytoplasm with distinct cytoplasmic borders. These cells were arranged in cohesive fascicles exhibiting a storiform pattern focally. Cytologically, this lesion can be differentiated from pituitary adenoma, astrocytoma, meningioma, and schwannoma.

Neurointermediate pituitary lobectomy decreases the incidence and severity of experimental autoimmune encephalomyelitis in Lewis rats

Acute experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system, mediated by T lymphocytes. Immunization of Lewis rats with myelin antigens suspended in complete Freund's adjuvant induces EAE. In a previous study on rats we have found that neurointermediate pituitary lobectomy (NIL) decreased both the humoral and cell-mediated immune responses. Here we investigated the effect of NIL on the incidence and severity of EAE and on the function of the hypothalamic-pituitary-adrenal axis in Lewis rats. NIL, hypophysectomized (Hypox) and sham-operated (Sham) rats were immunized s.c. with guinea-pig brain extract suspended in complete Freund's adjuvant. Untreated rats were used as controls. Water intake, body weight gain, clinical and histopathologic incidence and severity of EAE were evaluated in the operated groups. On killing, plasma adrenocorticotropin and corticosterone levels were measured and adrenals, thymuses and spleens were weighed. Histopathologic lesions were counted in the brain and spinal cord. Water intake and body weight gain were significantly decreased in Sham and Hypox animals with EAE whereas higher intakes persisted in the NIL group. Plasma levels of adrenocorticotropin were within the normal range whereas corticosterone levels increased in Sham and occasionally in NIL animals. Thymus weights were decreased in NIL and Hypox groups. The clinical and histopathologic incidence and severity of EAE were significantly decreased in NIL animals as compared with Sham and Hypox rats. We concluded that NIL affects the cell-mediated immune response and plays a role in the development and progression of EAE in the Lewis rat.

Pituicytoma

Pituicytoma is a rare, low-grade neoplasm that originates in the neurohypophysis of the pituitary gland. We report the clinicopathologic features of a pituicytoma arising in a 52-year-old man who presented with a mass and panhypopituitarism, clinically suggestive of a pituitary adenoma. The tumor was marked by a proliferation of elongated cells arranged in bundles and interlacing fascicles. The tumor demonstrated positive staining with S-100 protein and glial fibrillary acid protein antibodies. The tumor did not stain with antibodies to cytokeratin, synaptophysin, chromogranin, anterior pituitary hormones, or p53. An MIB-1 labeling index of 1.1% was observed. The tumor was subtotally resected and recurred 11 months after the initial surgery. The literature on this rare tumor will be reviewed and differential diagnosis discussed.

Suprapineal recess: an alternate site for third ventriculostomy?

✓ This 30-year-old woman presented with clinical symptoms and signs of intracranial hypertension and Parinaud syndrome secondary to ventriculoperitoneal shunt dysfunction. Magnetic resonance (MR) imaging revealed gross triventricular hydrocephalus with a large suprapineal recess due to aqueductal stenosis. Using an endoscopic approach, a ventriculostomy was performed within the floor of the dilated suprapineal recess. Following this procedure the patient experienced alleviation of all her neurological symptoms and signs. Postoperative MR imaging and cerebrospinal fluid flow studies demonstrated a functioning ventriculostomy. The anatomy of the suprapineal recess and its suitability for endoscopic ventriculostomy are discussed.

Growing teratoma syndrome in a patient with a non-germinomatous germ cell tumor in the neurohypophysis--case report

A 16-year-old woman presented with a non-germinomatous germ cell tumor in the neurohypophysis manifesting as progressive visual disturbance, amenorrhea, hydrodipsia, and polyuria. Her serum alpha-fetoprotein and human chorionic gonadotropin levels were elevated. She experienced sudden, rapid visual deterioration and underwent emergency partial tumor removal to decompress the optic nerves. Her vision subsequently improved. Histological examination of the surgical specimens confirmed immature teratoma. She received chemotherapy (ifosphamide 900 mg/m2, cisplatin 20 mg/m2, etoposide 60 mg/m2) for 5 consecutive days. Although the tumor marker levels decreased remarkably, her vision again declined rapidly due to enlargement of the tumor after the first course of chemotherapy. A second radical operation resulted in vision improvement. The tumor specimen showed only mature teratoma elements. This phenomenon, called the growing teratoma syndrome, is very rare in intracranial non-germinomatous germ cell tumors.

Infundibuloneurohypophysitis presenting a large sellar-juxtasellar mass: case report

BACKGROUND

Infundibuloneurohypophysitis (INH) is reported to be a self-limiting inflammatory disease involving neurohypophysis. The authors experienced a case of INH presenting a large mass compressing the brain stem.

CASE PRESENTATION

The patient exhibited polyuria followed by left hemiparesis and dysarthria lasting a year. Magnetic resonance imaging showed a large sellar mass extending into the right cavernous sinus and prepontine cistern and compressing pons. Endocrinologically, diabetes insipidus was diagnosed and anterior pituitary function was almost normal. Microscopic examination of the surgical specimen obtained by a transsphenoidal route demonstrated diffuse infiltration of lymphoid cells with predominance of B cells over T cells and the granulation tissue. The patient underwent 40 Gy local radiation because of initial misinterpretation of histologic findings as malignant lymphoma and short-term corticostertoid administration.

CONCLUSION

The mass gradually shrank and the patient has become neurologically intact in 6 months. At this moment, 67 months after the onset, the patient is free from disease and has no other lesion. INH seems to be a clinical entity possessing a wide spectrum from infundibular tumorlet to an aggressive sellar mass trespassing on surrounding structures.

Pituicytoma: Report of Two Cases and Clues Regarding Histogenesis

OBJECTIVE AND IMPORTANCE

The pituicytoma is a rare primary tumor of the neurohypophysis. Although histologically benign, the location and vascular nature of these tumors can make surgical resection difficult. We present a report of two patients with pituicytomas and review the literature regarding treatment and prognosis for this unusual lesion. Possible histogenetic relationships of this tumor with other pituitary neoplasms are presented.

CLINICAL PRESENTATION

Patient 1 was a 45-year-old man who presented with a 5-year history of decreased libido. He was found to have a 2-cm suprasellar mass on a magnetic resonance imaging scan. Patient 2 was a 48-year-old man who presented with multiple endocrine complaints. He was found to have an intrasellar mass on magnetic resonance imaging.

INTERVENTION

Patient 1 underwent a right frontal craniotomy, with a subtotal resection of the suprasellar mass through the lamina terminalis. The residual tumor was treated with fractionated stereotactic radiotherapy. The intrasellar mass in Patient 2 was resected via a transsphenoidal approach. On surveillance magnetic resonance imaging, the tumor was found to have recurred and expanded into the suprasellar space. The patient underwent a right frontal craniotomy for decompression and a subtotal resection of the tumor. The patient experienced a second recurrence 7 years after the initial procedure and was subsequently treated with fractionated stereotactic radiotherapy.

CONCLUSION

Pituicytomas are a distinct form of pituitary gland neoplasia that may recur if subtotally resected. These neurohypophysial tumors may contain a small subpopulation of previously unrecognized bcl-2-immunoreactive cells, whose role in the histogenesis of pituicytoma deserves further study.

Neurohypophyseal germinoma histologically misidentified as granulomatous hypophysitis

We report a case of neurohypophyseal germinoma appearing as predominantly granulomatous reaction in the first histological examination. A 12-year-old boy presented with diabetes insipidus, panhypopituitarism, and bitemporal hemianopsia. Transsphenoidal exploration for the intrasellar mass lesion extending to the suprasellar region was performed in May 1999. Histological examination revealed granulomatous hypophysitis and corticosteroid therapy was initiated. Six months later, the lesion relapsed despite corticosteroid therapy. Subtotal removal of the lesion was performed via an anterior interhemispheric approach in December 1999. Histological examination revealed typical germinoma. Subsequently, the patient underwent irradiation of 20 Gy to the tumour site and 24 Gy to the whole brain. Magnetic resonance imaging confirmed tumour remission. We must consider the possibility of neurohypophyseal germinoma in patients with granulomatous hypophysitis which does not respond to corticosteroid therapy, and perform re-exploration for more specimens to achieve the correct diagnosis.

[Corticotroph microadenomas of the pituitary stalk. Diagnostic and therapeutic difficulties]

Thirteen percent of the pituitary adenomas in our series have been corticotroph adenomas. Most have been microadenomas located in the adenohypophysis, more often laterally than posteromedially. In a few rare cases, the corticotroph cells of the pars tuberalis gave rise to an adenoma. Only 16 cases of pituitary stalk adenomas have been published to date. We report here three new cases among a series of 150 patients who underwent surgery for corticotroph adenomas (2% incidence as in the literature). There was no difference in the clinical or biological presentation of intrasellar and pituitary stalk adenomas. This location must be systematically searched on the MRI, but a negative exploration cannot excluded the diagnosis of pituitary stalk adenoma like in intrasellar ones. Two anatomical entities seems to be separated. Some stalk adenomas developed preferentially in the supradiaphragmatic space (one in our series) and are accessible for selective resection. Others develop within the pituitary stalk itself and sometimes in the pars distalis (two patients in our series) which requires section of the pituitary stalk with hypophysectomy if the lower limit is not clearly seen during surgery. The subfrontal or pterional access is the approach of choice for suprasellar tumors. These approaches remain controversial for pituitary stalk adenomas because of the poor visibility of the pituitary stalk and the floor of the third ventricle. The transnasosphenoidal approach with extension to the sphenoidal planum and opening of the optochiasmatic cisterna appears to be the best alternative for surgical removal of these adenomas.

Changes in the epithelium of Rathke cleft cyst associated with inflammation

OBJECT

Rathke cleft cysts (RCCs) are composed of tall, well-differentiated, ciliated columnar epithelia. Their structures are altered by hyperplasia or squamous metaplasia, but their cause remains unknown.

METHODS

The authors studied pathological findings and anterior pituitary function in 20 patients harboring RCCs. They classified RCC epithelium as either single (a single ciliated columnar cell lining or a flattened cuboidal cell lining) or stratified (a stratified ciliated columnar cell lining, basal cell hyperplasia, columnar cell hyperplasia, or squamous metaplasia). Inflammation was classified as acute, subacute, chronic, or end stage. The epithelial cell lining was observed in 13 specimens obtained during surgery (six specimens contained single and seven contained stratified epithelia). Inflammation had penetrated the cyst epithelium or subjacent stroma in 10 patients, and the stage of inflammation correlated well with the type of epithelia group: early stages of inflammation in the single epithelium group and chronic or end-stage inflammation in the stratified epithelia (p = 0.0027). The adenohypophysis was identified in 21 surgical specimens. Postoperatively, growth hormone (p = 0.019), cortisol (p = 0.027), and thyroid-stimulating hormone (p = 0.039) responses significantly worsened as the inflammation progressed. The presence of diabetes insipidus correlated well with advanced stages of neurohypophysitis (p = 0.025).

CONCLUSIONS

Epithelial stratification in the RCC is caused by inflammation that may extend into the adjacent adenohypophysis or neurohypophysis and overwhelm the hypophysis, resulting in panhypopituitarism. Transsphenoidal excision may represent the best choice for treatment, at least for cases of RCC in which there is partial impairment of hypophysial function.

Metachronous neurohypophysical immature teratoma occurring 10 years after total resection of pineal mature teratoma

An 18-year-old boy presented with an immature neurohypophysial teratoma occurring 10 years after total resection of a mature pineal teratoma through an occipital transtentorial approach in 1989. Thorough histological examination had revealed a mature teratoma. He developed panhypopituitarism and diabetes insipidus in 1999. Magnetic resonance imaging revealed a suprasellar tumor occupying the third ventricle. This tumor was totally resected through a frontobasal approach. Histological examination revealed an immature teratoma. This tumor occurred in a different site from the initial tumor and was considered to be de novo and thus a so-called metachronous germ cell tumor. Patients with completely resected mature teratoma require extended follow-up, including periodic magnetic resonance imaging, because of the risk of such a metachronous germ cell tumor.

Adenovirus-mediated gene delivery to cells of the magnocellular hypothalamo-neurohypophyseal system

The objective of the present study was to define the optimum conditions for using replication-defective adenovirus (Ad) to transfer the gene for the green fluorescent protein (GFP) to the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei and cells of the neurohypophysis (NH). As indicated by characterizing cell survival over 15 days in culture and in electrophysiological whole cell patch-clamp studies, viral concentrations up to 2 x 10(7) pfu/coverslip did not affect viability of transfected PVN and NH cultured cells from preweanling rats. At 2 x 10(7) pfu, GFP gene expression was higher (40% of GFP-positive cells) and more sustained (up to 15 days). Using a stereotaxic approach in adult rats, we were able to directly transduce the PVN, SON, and NH and visualize gene expression in coronal brain slices and in the pituitary 4 days after injection of Ad. In animals receiving NH injections of Ad, the virus was retrogradely transported to PVN and SON neurons as indicated by the appearance of GFP-positive neurons in cultures of dissociated cells from those brain nuclei and by polymerase chain reaction and Western blot analyses of PVN and SON tissues. Adenoviral concentrations of up to 8 x 10(6) pfu injected into the NH did not affect cell viability and did not cause inflammatory responses. Adenoviral injection into the pituitary enabled the selective delivery of genes to the soma of magnocellular neurons. The experimental approaches described here provide potentially useful strategies for the treatment of disordered expression of the hormones vasopressin or oxytocin.

A case of atypical granular cell tumor of the neurohypophysis

A case of granular cell tumor (GCT) arising in the neurohypophysis of a 63-year-old woman is reported. The tumor consisted of ovoid, polygonal or spindle-shaped cells in a sheet-like or fascicular arrangement. Its abundant cytoplasm contained granules positive for diastase-resistant periodic acid-Schiff reaction. Ultrastructurally, the tumor cells contained numerous polymorphic lysosomes of various densities. Immunohistochemically, the tumor cells were positive for S-100 protein, glial fibrillary acidic protein and Leu7, suggesting that the tumor originated from pituicytes that were thought to be modified astrocytes in the neurohypophysis and its stalk. The granular cells showed nuclear atypia, pleomorphism and increased mitotic activity. Therefore, the present tumor was considered as a histologically atypical GCT. Interestingly, proliferating cell nuclear antigen, Ki-67 and p53 were stained in a few tumor cells of this case. These findings indicate that the present tumor had a malignant potential.

Adrenomedullin-like immunoreactivity in the rat hypothalamo-neurohypophysial tract

Adrenomedullin-like immunoreactivity in the hypothalamo-neurohypophysial tract in colchicine-treated and hypophysectomized rats was examined by immunohistochemistry. Adrenomedullin-like immunoreactive (AM-LI) neurons were localized in the hypothalamic areas, including the paraventricular nuclei and the supraoptic nuclei. Abundant AM-LI fibers and varicosities were found in the hypothalamoneurohypophysial tract and the internal zone of the median eminence in the colchicine-treated and hypophysectomized rats, whereas in control rats few AM-LI fibers were observed. These results suggest that the axons of the AM-LI neurons in the hypothalamus may terminate in the neurohypophysis.

Atypical granular cell tumor of the neurohypophysis: a case report with review of the literature

A 76-year-old man had an atypical granular cell tumor of the neurohypophysis which showed pleomorphic nuclei, mitotic figures, and spindle-shaped cells, extremely rare findings to be encountered. Review of 45 patients with neurohypophyseal granular cell tumor revealed a ratio of 1:2 between male and female with the peak occurrence (31%) in the fifth decade, and with the mean age of 50 years. There were no patients below 20 years of age. The common clinical presentations included visual disturbances and endocrinopathies relating to sex hormones. Surgical removal was the treatment of choice. If it is possible, total extirpation should be attempted. Because of uncertain cellular origin, the lesion should be descriptively diagnosed as granular cell tumor although multiple terms have been proposed.

[Granular cell tumors. Rare tumors of the neurohypophysis]

Granular cell tumours of neurohypophysis are rare. These tumours are more often encountered as incidental autopsy findings seen in up to 17% of unselected adult autopsy cases. There are few reports of parasellar granular cell tumours large enough to cause symptoms. We present three cases of neurohypophysis granular cell tumour and a review of the literature. In one patient, the asymptomatic granular cell tumour was incidentally discovered at surgical removal of a corticotroph microadenoma. The remaining 2 patients had a symptomatic tumour which caused neurological symptoms such as visual disturbance and headaches and endocrine disorders such as hypopituitarism or hyperprolactinaemia. In these 2 cases, computerized tomography showed a well-circumscribed, contrast-enhanced, intrasellar and suprasellar mass. Magnetic resonance imaging demonstrated an isointense gadolinium-enhanced mass in T1-weighted images. Transsphenoidal partial resection was performed and histology was interpreted as a granular cell tumour. The immunohistochemical study was positive for glial fibrillary acidic protein (GFAP) and neuron specific enolase (NSE) in 1 of the 2 tumours and positive for S100 protein and vimentin in both tumours but negative for CD68. The histogenesis of neurohypophysis granular cell tumours is still controversial but ultrastructural and immunohistochemical studies support the theory that they may arise from pituicytes, the glial cells of neurohypophysis. Management of these benign, slow-growing, tumours is based mainly on neurosurgical resection. Data from the literature do not support a beneficial effect of postoperative radiation therapy on postoperative recurrences.

Magnetic resonance imaging and pathological analysis of a pituicytoma: case report

A case of a pituicytoma is presented that describes the clinical, pathological, and magnetic resonance imaging features of a rare tumor of the neurohypophysis. A 26-year-old woman presented with a 4-month history of dizziness and visual obscuration. A magnetic resonance image revealed a pituitary mass with suprasellar extension. The specimen obtained from a transsphenoidal decompression identified the mass as an astrocytoma of the posterior pituitary (pituicytoma). Immunohistochemical staining was positive for glial fibrillary acidic protein, S-100, and vimentin. Electron microscopy identified intermediate filaments, numerous broad cell junctions, no secretory granules, and two cellular populations with either an electron-dense or lucent cytoplasmic matrix. This case is unique in that other documented cases originating in the posterior pituitary have all been pilocytic astrocytomas, whereas this neoplasm was not a pilocytic variant. This is also the first case in the literature of a pituicytoma documented by magnetic resonance imaging. This report reviews the cytological elements of the neurohypophysis and the origin of pituicytomas and stresses the proper use of the term "pituicytoma" in relation to tumors of the posterior pituitary.

Effect of alcohol, neurohypophysectomy, and vasopressin antagonists on hemorrhage-induced bradycardia in the rat

During initial stages of hemorrhage in the rat, cardiovascular compensation leads to a tachycardia (mean +/- SE, 5.2 +/- 0.7%; n = 23) that helps prevent a large fall in blood pressure. This compensatory phase is followed by a decompensatory phase in which mean arterial pressure and heart rate fall. A rise in arginine vasopressin (AVP) levels has been postulated as the cause of this hemorrhage-induced bradycardia (HIB). The object of the present study was to determine whether interference with AVP release by alcohol anesthesia or neurohypophysectomy or by blockade of AVP receptors in the plasma or cerebral spinal fluid could attenuate HIB. Male Wistar rats were anesthetized with pentobarbital, surgically prepared, and bled to maintain a blood pressure of 40-50 mm Hg. After hemorrhage, heart rate decreased 15 +/- 2% (n = 6) with alcohol anesthesia compared with 32 +/- 3% (n = 7) with pentobarbital. After neurohypophysectomy, however, HIB remained unchanged (-15 +/- 2%; n = 5) compared with sham-operated controls (-19 +/- 3%; n = 6). Peripheral administration of two nonselective V1/V2 antagonists and one V2 antagonist had no effect on HIB, whereas a V1 antagonist significantly attenuated the heart rate decrease (-15 +/- 4%; n = 6) compared with controls (-32 +/- 3%; n = 7). None of the AVP antagonists tested at one tenth the peripheral dose had any effect on HIB when administered into the lateral ventricle of the brain, although a mixed serotonin, dopamine, and catecholamine antagonist, spiperone, potentiated the response. It was concluded that although peripheral release of AVP may be partially involved in the heart rate response to hemorrhage, central AVP release and central AVP receptors were not involved in HIB.

Influence of oxytocin on sodium excretion in the anaesthetized Brattleboro rat

The contribution of oxytocin to the maintenance of renal Na+ excretion in the Brattleboro rat has been examined in animals infused with hypotonic saline. Brattleboro rats exhibited hypernatraemia and hyperosmolality associated with greatly increased plasma concentrations of oxytocin by comparison with Long-Evans control rats. Neurohypophysectomy to remove the secretion of the remaining posterior pituitary peptide, oxytocin, led to greatly diminished rates of Na+ excretion in the Brattleboro rat. Oxytocin replacement to achieve plasma levels equivalent to those in intact Brattleboro rats produced a substantial and sustained natriuresis in the neurohypophysectomized animal. Oxytocin secretion evoked in response to saline infusion would thus appear to be effective in promoting renal Na+ excretion in the absence of vasopressin in the Brattleboro rat.

Acute stimulation of prolactin release by estradiol: mediation by the posterior pituitary

We have previously shown that the posterior pituitary contains a potent PRL-releasing factor (PRF). Estradiol stimulates PRL release by acting at three possible sites: the hypothalamus, the anterior pituitary, and the posterior pituitary. The objectives were 1) to document the profiles of PRL and LH release in response to an acute administration of estradiol, and 2) to identify the site of action of estradiol by employing two surgical approaches, pituitary stalk section (SS) and posterior pituitary lobectomy (LOBEX). Ovariectomized rats were used throughout. In Exp 1, rats were injected iv with 5 micrograms/kg 17 beta-estradiol, and blood was collected at 30-min intervals for 4 h. Estradiol induced a rapid and profound decline in plasma LH levels and a delayed, 5- to 6-fold rise in PRL. The purpose of the second experiment was to determine whether estradiol stimulates PRL release by acting at the anterior pituitary. Injection of estradiol to SS rats failed to stimulate a rise in PRL. We have previously reported that lactotrophs of SS rats are responsive to PRL secretagogues such as TRH. The objective of the third experiment was to differentiate between hypothalamic and posterior pituitary sites of estradiol action. Estradiol induced only a small rise in PRL when injected into LOBEX rats. However, LOBEX and control rats showed similar large rises in PRL in response to injection of alpha-methyl-para-tyrosine, an inhibitor of tyrosine hydroxylase. The latter indicates that the hypothalamic dopaminergic system as well as anterior pituitary lactotrophs are functionally intact in LOBEX rats. We conclude that estradiol administration to ovariectomized rats induces a rapid decline in LH and a delayed marked increase in PRL. The posterior pituitary, probably via PRF, is the primary site that mediates the acute effects of estradiol on PRL release. Estradiol does not stimulate PRL release directly from the anterior pituitary. The role of the hypothalamus is unclear. Estradiol could act directly on PRF-containing cells in the posterior pituitary or indirectly, via hypothalamic neurons terminating in the posterior pituitary. The hypothalamus also has a minor component that responds to estradiol and is independent of the posterior pituitary.

Prolactin response to immobilization stress and hemorrhage: the effect of hypothalamic deafferentations and posterior pituitary denervation

The roles of posterior and anterolateral connections to the mediobasal hypothalamus (MBH) as well as innervation of the posterior pituitary in the PRL response to immobilization (IMO) and hemorrhage (HEM) were studied by means of surgical isolation, performed 6-9 days before stress exposure. Male rats bearing indwelling tail artery cannulae subjected to 120-min IMO reached peak PRL secretion in 5-20 min. HEM of 25% elicited a significant rise of PRL levels. A posterior cut in the MBH, performed without damaging the serotonergic fibers from the brain stem, attenuated the PRL response to 25% HEM, whereas the PRL elevation due to IMO remained unaffected. An anterolateral cut around the MBH eliminated both the IMO- and HEM-induced stimulation of PRL. Posterior lobe denervation reduced by about 27% the PRL response to IMO and eliminated the response to HEM. These results suggest the following conclusions. The neural structures located posteriorly to the MBH are involved in the transfer of signals triggering PRL secretion due to hypovolemia. Intact anterolateral pathways to the MBH and stalk-median eminence region are essential for the PRL-releasing activity under both stimuli. The posterior lobe may be an important link in the PRL stress response in male rats.

Pituitary stalk agenesis: magnetic resonance imaging of 'ectopic posterior lobe' with surgical correlation

A patient with anterior pituitary deficiencies, without diabetes insipidus, was found to have a retrochiasmatic mass in association with a large middle fossa cyst on CT and MRI scans, and no tissue in the sella ('empty sella'). At surgery, the pituitary stalk was absent. The retrochiasmatic mass was biopsied and shown to be consistent with pituitary stalk. Recent descriptions of MR visualization of an 'ectopic' posterior pituitary lobe are discussed in relation to this case of agenesis of the pituitary stalk and posterior lobe.

Prolactin secretion in posterior pituitary lobectomized rats: differential effects of 5-hydroxytryptophan and ether

The objective of this study was to determine whether the posterior pituitary mediates the prolactin (PRL) releasing activities of serotonin and ether. Ovariectomized (OVEX) rats were subjected to posterior pituitary lobectomy (LOBEX) or sham surgery (SHAM). Either 1 or 12 days after surgery, rats were injected i.v. with 20 mg/kg b. wt. of 5-hydroxytryptophan (5-HTP), which is a precursor of serotonin. A second group of rats was exposed to ether vapors for 10 min. Blood was collected from a jugular cannula before and after the treatments and analyzed for PRL. On either 1 or 12 days after surgery, injection of 5-HTP increased plasma PRL levels 5-10 fold in both LOBEX and SHAM rats. This was followed by a decline to preinjection levels within 60-90 min. LOBEX and SHAM male rats which were injected i.p. with 50 mg/kg b. wt. of 5-HTP, also showed marked and similar elevations of plasma PRL levels 12 days after surgery. Exposure of OVEX rats to ether elicited a 2-3 fold rise in plasma PRL levels only on day 1, but not on day 12, after LOBEX. The ether-induced rise in PRL was similar in SHAM rats tested on both days. These results indicate that the 5-HTP-induced rise in plasma PRL levels is independent of the posterior pituitary, regardless of the sex, the route of drug administration or the length of time after surgery. In contrast, the PRL response to ether stress is diminished within 12 days after LOBEX. The evidence that the PRL responses to 5-HTP and to ether might be mediated via different neuronal mechanisms is discussed.

Chronic posterior pituitary lobectomy: prolonged elevation of plasma prolactin and interruption of cyclicity

We previously reported that the posterior pituitary dopaminergic system participates in the inhibition of prolactin (PRL) secretion in both male and lactating female rats. However, posterior pituitary lobectomy (Lobex) of urethane-anesthetized cycling rats resulted in an elevation in plasma PRL for a short time only. This raises a question regarding the importance of input from the posterior pituitary to the control of PRL secretion during the estrous cycle. The objectives of this study were to examine the chronic effects of Lobex on plasma PRL levels in conscious rats and to determine whether the absence of input from the posterior pituitary interferes with estrous cyclicity. Lobex or sham lobectomy were performed under Brevital anesthesia in estrous rats. Blood was collected from jugular cannula at hourly intervals on the day of surgery and at 09.00, 13.00, and 17.00 h during the following 4 days. Daily water consumption and vaginal cyclicity were monitored for 14 and 20 days, respectively. Within 2 h after Lobex, the plasma PRL levels rose 3- to 4-fold and remained elevated for 3 days before declining to near control levels on the 4th day. None of the Lobex rats resumed cyclicity within 3-4 days, 50% had an interruption of cyclicity for 4-10 days, and the remainder were noncyclic for more than 11 days. Upon resumption of cyclicity, Lobex rats had 11.3 +/- 0.4 oviductal ova which is within the normal range for intact ovulating rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Section of the pituitary stalk in the rhesus monkey: morphological and endocrine observations

The effect of sectioning the pituitary stalk on the hypothalamic magnocellular system of the rhesus monkey was studied by specific immunocytochemical techniques. Regeneration of the proximal stump with reconstitution of a "new" neurohypophysis occurred as early as three weeks after operation, illustrating the remarkable regenerative ability of the system. The functional capacity of the newly formed neurovascular units was also tested, and the results indicate that they not only resume basal secretion of posterior pituitary hormones, but are also able to increase their output in response to a variety of challenges.

Pituitary stalk-section and some of its effects on endocrine function in the fetal lamb

A detailed description is given of a method to section the pituitary stalk of the fetal lamb after 105 days gestational age. The approach to the stalk is made through a window in the frontal bone. In order to prevent regeneration of the hypothalamo-pituitary connections a silicone plate is introduced through the probe used to fracture the stalk. The surgical outcome and viability of 11 pituitary stalk sectioned fetuses is described over periods of up to 23 days. The presence of pituitary infarction following stalk section was related to damage of the anterior hypophysial vesssels if the probe was deviated from the mid-line at any time in its course. The effect of this procedure on fetal plasma T4 and PRL concentrations and the initiation of premature labour by the continuous infusion of cortisol into the fetus is described.

Ultrastructural changes in the placenta of the ewe after fetal pituitary stalk section

Binucleate cells are a normal component of the ovine chorionic epithelium, but are usually separated from the fetal-maternal interface by a thin layer of cytoplasm derived from the principal or uni-nucleate cells of the trophoblast. They are distinguished not only by two distinct and separate nuclei, but also by conspicuous membrane-bound cytoplasmic inclusions in the form of haloed droplets. After fetal pituitary stalk section binucleate cells move up to and participate in the formation of the fetal-maternal interface; furthermore they extend clear blunt-ended pseudopodia into the maternal epithelial syncytium. These activities do not appear to be supppressed by fetal infusion of cortisol or ACTH. The apparent motility of binucleate cells, together with the presence of haloed droplets within the maternal epithelial syncytium, suggests that after fetal pituitary stalk section binucleate cells invade the uterine syncytium, lose their limiting membranes and discharge their contents into the syncytial cytoplasm. Large molecules such as ovine placental lactogen may be transported from fetal to maternal tissues by this mechanism.

Transoral, transsphenoidal microsurgical exposure of the pituitary gland and infundibulum in the rhesus monkey. Description of operative technique

A transoral, transsphenoidal microsurgical technique for exposing the pituitary stalk and gland of the rhesus monkey is described and illustrated. The technique has proved to be a safe and practical method for performing a variety of pituitary operations in a total of 37 animals. The procedures have included complete hypophysectomy, posterior lobe resection, pituitary stalk section, collection of portal venous blood, collection of pituitary venous blood, and placement of lessions in the organum vasculosum of the lamina terminalis.

Lactation in the rat after hypophysial posterior lobectomy

Ablation of the posterior lobe of the pituitary in the lactating rat abolished the milk-ejection reflex so that the pups could only be reared if injections of oxytocin were given to the mothers twice daily. When, however, these posterior lobectomized rats became pregnant a second time, parturition was normal and the milk-ejection reflex was sufficiently restored for the rats to rear their litters without oxytocin being administered. The animals, however, continued to exhibit diabetes insipidus. Measurements of residual neurohypophysial tissue showed that hypertrophy of the neural stalk had occurred after posterior lobectomy.

These findings are discussed in relation to recent studies on the site of formation and the liberation of posterior-pituitary hormone(s) after hypophysectomy.