Idiopathic central diabetes insipidus is associated with abnormal blood supply to the posterior pituitary gland caused by vascular impairment of the inferior hypophyseal artery system

Central diabetes insipidus (CDI) has been linked to vascular central nervous system damage, although the pathophysiology of the mechanism has never been perfectly understood. Indeed, the vascular system of human pituitary gland has rarely been the subject of rigorous investigation except at postmortem. Recently, studies of pituitary gland blood supply have been carried out by means of a time evaluation of pituitary gland enhancement with noninvasive dynamic magnetic resonance (MR) imaging after contrast medium injection. In the present study, we decided to investigate the status of posterior pituitary blood supply by evaluating vascular pituitary patterns in a group of 19 patients with idiopathic CDI in whom previous standard MR imaging had failed to identify causal specific lesions. The control group was composed of 55 subjects with a median age of 12 yr (range, 4.2-17 yr) who had idiopathic isolated GH deficiency and normal pituitary morphology and 15 young adults (18-25 yr) who had normal pituitary gland and no endocrine dysfunction. Nineteen patients (12 females and seven males), ranging in age at the time of diagnosis of CDI from 0.5-14.9 yr (median, 5 yr), were examined with dynamic MR imaging between 1990 and 1997 at a median age of 14.1 yr (range, 5.0-26.3 yr). CDI was diagnosed according to clinical findings of polyuria and polydipsia, water deprivation test, and desmopressin acetate therapeutic trial. All of the patients had permanent CDI and were being treated with satisfactory results with desmopressin, two to three times daily, either intranasally or orally. The previous MR imaging findings of the 19 CDI patients had shown the absence of posterior pituitary hyperintensity, normal pituitary stalk, and normal anterior pituitary size. Enhancement of the straight sinus, representing a temporal reference point and occurring in normal subjects simultaneously to that of the posterior pituitary gland, was observed in all subjects after iv gadopentetate dimeglumine administration, with no substantial differences between patients and controls. However, the enhancement of the posterior pituitary lobe occurred simultaneously with the enhancement of the straight sinus in all of the controls but in only 14 of the 19 patients with CDI. In the remaining five patients, the enhancement of the straight sinus was not associated with the expected contrast enhancement of the posterior pituitary gland, suggesting abnormal blood supply to the posterior pituitary lobe. This is in keeping with vascular impairment of the inferior hypophyseal artery system and suggests that abnormal blood supply to the posterior pituitary gland is associated with what, until now, has been considered idiopathic CDI.

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.

Morning glory syndrome associated with posterior pituitary ectopia and hypopituitarism

PURPOSE

To report a patient with morning glory syndrome in combination with posterior pituitary ectopia and to emphasize the need for early recognition of this syndrome as an important step towards the diagnosis and treatment of the systemic anomalies that may be associated with it.

METHODS

We present a 7-year-old boy who showed short stature, nystagmus, inward deviation and low vision. Ophthalmological and general physical examinations, further endocrine evaluation and magnetic resonance imaging (MRI) of the brain and sella turcica were performed.

RESULTS

Both fundi showed symptoms of morning glory syndrome. The discs were pink and deeply excavated, and were surrounded by a ring of chorioretinal pigmentary disturbance. Magnetic resonance imaging revealed the absence of the infundibulum and posterior pituitary ectopia. Growth hormone studies confirmed the diagnosis of growth hormone deficiency. Therapy with recombinant human growth hormone was initiated.

CONCLUSIONS

Although most cases of morning glory syndrome occur as isolated ocular abnormalities, it may occur in association with systemic anomalies, including posterior pituitary ectopia and hypopituitarism. A complete general physical examination and growth evaluation is important for early detection and treatment, resulting in benefit for these patients.

Symptomatic granular cell tumor of the neurohypophysis

Symptomatic granular cell tumors of the neurohypophysis or infundibulum are very rare neoplasms which are difficult to diagnose before operation. We report a case of symptomatic granular cell tumor of the neurohypophysis in a 36-year-old woman who had suffered from amenorrhea and general malaise for more than 1 year. No definite visual or neurological deficit was found. Laboratory examination revealed hyperprolactinemia and decrease of other pituitary hormones. T1-weighted magnetic resonance imaging (MRI) revealed an isointense sellar mass with suprasellar extension. Transsphenoidal subtotal tumor removal was performed and pathological examination revealed a granular cell tumor of the neurohypophysis composed of densely packed polygonal cells with abundant eosinophilic, granular cytoplasm. The granules were periodic acid-Schiff-positive and diastase-resistant. Immunohistochemical study showed positive reaction for S-100 protein and antitrypsin antibodies. Electron microscopic examination showed numerous lysosomes in the cytoplasm of tumor cells. The postoperative MRI showed the residual tumor to be just behind the pituitary stalk and that the tumor should arise from the posterior lobe of the pituitary gland. The postoperative course was smooth and there were no sequelae during 30 months of regular follow-up. We believe surgery remains the treatment of choice and even partial removal of the tumor may benefit the patient.

Elevated levels of human chorionic gonadotropin-beta, a marker of active neurohypophyseal germinoma, detected by immune complex transfer enzyme immunoassay

We report the usefulness of a highly sensitive immune complex transfer enzyme immunoassay (ICT-EIA) to detect human chorionic gonadotropin (HCG)-beta and thereby the onset of neurohypophyseal germinoma in its active phase. A 14-year-old girl exhibiting arrested puberty was diagnosed with neurohypophyseal germinoma following observation for two years. This patient initially showed no signs of diabetes insipidus (DI). While ICT-EIA indicated concentrations of HCG-beta higher than normal in cerebrospinal fluid (CSF) and serum, the results obtained with conventional methods were negative. ICT-EIA was also useful to assess the efficacy of treatment.

Diabetes insipidus: historical aspects

The contributions to our present knowledge and understanding of diabetes insipidus are briefly surveyed. Though a disease presenting with polyuria and thirst had been recognized since Antiquity, it was not until the 17. Century the distinction was made between diabetes insipidus and diabetes mellitus. At the beginning of the 20. Century almost nothing was known about the function of the pituitary. It was generally believed that diabetes insipidus was a renal disease. Two clinical observations in 1912 suggested an association between the hypophysis and diabetes insipidus. This view was supported by the recognition in 1913 that extract of the posterior lobe of the pituitary was effective in diabetes insipidus. Despite much evidence to the contrary, it was assumed that the antidiuretic hormone was produced in the intermediate lobe of the pituitary. Around 1950 it was finally established that 'the posterior lobe hormones' are in fact secreted in the hypothalamus. At the same time the antidiuretic hormone was isolated and synthesized. More recently, progress within genetics has made it possible to characterize in details other rare types of diabetes insipidus.

Clinical Characteristics and Molecular Analysis of PIT1, PROP1,LHX3, and HESX1 in Combined Pituitary Hormone Deficiency Patients with Abnormal Pituitary MR Imaging

BACKGROUND/AIMS

Many genes encoding pituitary transcription factors involved in the formation of the pituitary gland are identified. Different mutations in these genes have been reported in patients with familial combined pituitary hormone deficiency (CPHD). This study was undertaken to analyze PIT1, PROP1, LHX3, and HESX1 in 12 CPHD patients with abnormal pituitary magnetic resonance imaging (MRI). Since embryonic development of the pituitary requires the coordinated expression of specific transcription factors, we postulated the presence of mutations in PIT1, PROP1, LHX3, and HESX1 genes.

METHODS

Anterior pituitary function was evaluated. Each gene was PCR amplified exon by exon, and subsequently sequenced.

RESULTS

In all cases, MRI examination showed abnormal pituitary gland development featuring ectopic neurohypophysis, hypoplastic anterior lobe, empty sella, and septo-optic dysplasia. Endocrinologically, all patients revealed multiple pituitary hormone deficiency including growth hormone, thyroid stimulating hormone, luteinizing hormone, follicular stimulating hormone and adrenocorticotropin. They were all sporadic cases without a positive family history. None of disease-causing specific mutations were identified in PIT1, PROP1, LHX3, and HESX1 genes of 12 sporadic CPHD patients with abnormal pituitary imaging. However, 2 novel polymorphisms were found in PROP1 gene: IVS1+3 A-->G and 27 T-->C (Ala9Ala) in exon 1. Their allele frequencies in patients and normal controls were not statistically different. Overall, allele frequencies of these polymorphisms were as follows: for the IVS1+3 A-->G polymorphism, the allele frequency of A was 54%, and 46% for G, with 58% of an A/G heterozygosity. For the 27 T-->C (Ala9Ala) polymorphism, the allele frequency of T was 46%, and 54% for G, with 42% of a T/C heterozygosity.

CONCLUSIONS

Mutations of PIT1, PROP1, LHX3, and HESX1 genes are very rare in sporadic CPHD patients with abnormal pituitary MRI.

Diabetes insipidus

Diabetes insipidus is a heterogeneous condition characterized by polyuria and polydipsia caused by a lack of secretion of vasopressin, its physiological suppression following excessive water intake, or kidney resistance to its action. In many patients, it is caused by the destruction or degeneration of the neurons that originate in the supraoptic and paraventricular nuclei of the hypothalamus. Known causes of these lesions include: germinoma or craniopharyngioma; Langerhans cell histiocytosis and sarcoidosis of the central nervous system; local inflammatory, autoimmune or vascular diseases; trauma following surgery or accident; and, rarely, genetic defects in vasopressin biosynthesis inherited as autosomal dominant or X-linked recessive traits. Thirty to fifty percent of cases are considered idiopathic. Magnetic resonance imaging (MRI) allows identification of the posterior pituitary hyperintensity and of hypothalamic-pituitary abnormalities. Thickening of the pituitary stalk is the second most common finding on MRI scans in several local inflammatory pathologies and autoimmune diseases or germinoma, but it is not specific to any single subtype. A progressive increase in the size of the anterior pituitary gland should alert physicians to the possibility that a germinoma is present, whereas a decrease can suggest the presence of an inflammatory or autoimmune process. Most children with acquired central diabetes insipidus and a thickened pituitary stalk have anterior pituitary hormone deficiencies during follow-up. Biopsy of enlarged pituitary stalk should be reserved for patients with a hypothalamic-pituitary mass and progressive thickening of the pituitary stalk, since spontaneous recovery may occur.

MRI of ectopic posterior pituitary bright spot with large adenomas: appearances and relationship to transient postoperative diabetes insipidus

MRI of large pituitary adenomas has revealed that a posterior pituitary bright spot (PPBS), comprising ADH-containing neurosecretory granules, is commonly ectopic before surgery and attached to the tip of the pituitary stalk late after surgery. Although the PPBS indicates functional integrity of the posterior lobe, transient diabetes insipidus (DI), caused by deficiency of ADH, is frequent early after surgery. We attempted to clarify how the shape, signal intensity and site of the PPBS before surgery are related to transient DI in the early postoperative period. We carried out MRI on 15 patients with a large adenoma and an ectopic PPBS before surgery and then within 1 week (early), 1-2 months (intermediate) and 6 or more months (late) after the operation. There were nine who had transient DI, which subsided by the intermediate study; none had permanent DI. Regardless of transient DI, the PPBS was visible, and its signal intensity was similar, on all postoperative studies. Although 11 did not change in shape, four showed a remarkable change from a flat shape before surgery to a rounded one postoperatively. On the intermediate MRI, the PPBS had descended to the level of the diaphragma as mass effect disappeared.

Pilocytic astrocytoma of neurohypophysis

A case of pilocytic astrocytoma of neurohypophysis is presented. The clinical, pathological and MRI features of a rare tumor of the neurohypophysis are described. A 5-year-old girl presented with a 3 month history of lethargy, imbalance and visual disturbances. A MRI revealed a large suprasellar mass. Histopathological examination demonstrated a pilocytic astrocytoma. Its astrocytic nature was confirmed by positive immunostaining for GFAP and the findings of an electron microscopy.

Septo-optic dysplasia with congenital hepatic fibrosis

This article reports a 7-year-old female with septo-optic dysplasia and congenital hepatic fibrosis. She manifested nystagmus and severe hepatosplenomegaly. Brain magnetic resonance imaging revealed agenesis of the septum pellucidum, optic nerve hypoplasia, pituitary gland stalk hypoplasia, and absence of the posterior pituitary gland. She was diagnosed with growth hormone deficiency, hypothyroidism, diabetes insipidus, and adrenal insufficiency. Thus, this case was regarded as septo-optic dysplasia. No mutation was evident in the coding and boundary regions of the homeobox gene HESX1. Percutaneous biopsy of the liver demonstrated the presence of broad septa of fibrous tissue containing abundant bile ducts without inflammatory cell infiltrates, a finding compatible with congenital hepatic fibrosis. Although there is an association between septo-optic dysplasia and neonatal cholestasis, believed to be related to hypopituitarism, this case of septo-optic dysplasia with congenital hepatic fibrosis is apparently the first reported in the English literature.

Transient central diabetes insipidus in pregnancy with a peculiar change in signal intensity on T1-weighted magnetic resonance images

A 38-year-old woman was admitted with severe thirst and polyuria at 31 weeks' gestation. The plasma concentration of vasopressin (AVP) was very low (0.73 pg/ml) under conditions of high plasma osmolality (316 mOsm/ kg). T1-weighted magnetic resonance (MR) images revealed enlargement of the pituitary posterior lobe with absence of the hyperintense signal. After delivery, restoration of the hyperintense signal was demonstrated. This depletion-repletion process, which reflects the decrease and increase in amount of neurosecretory granules, is recognized in the case of transient central diabetes insipidus during pregnancy. We consider that an increase in cystine-aminopeptidase (CAP) activity is implicated in the pathogenesis.

Suprasellar peri-infundibular ectopic prolactinoma--case report

A 21-year-old man presented with bitemporal hemianopia and hyperprolactinemia. Magnetic resonance (MR) imaging showed a suprasellar cystic tumor in contact with the pituitary stalk. The diagnosis was craniopharyngioma. Intraoperatively, there was no clear continuity between the tumor and the tissue of the anterior lobe of the pituitary gland. The pituitary stalk and the diaphragma sellae were intact, and their morphology remained almost completely normal after the tumor was removed. The histological diagnosis was prolactin-producing pituitary adenoma. Postoperatively, the bitemporal hemianopia improved, and the serum prolactin levels returned to normal. The final diagnosis was suprasellar ectopic pituitary adenoma arising in the peri-infundibular region. Follow-up MR imaging at 1 year showed a normal pituitary stalk and pituitary gland, with no evidence of residual tumor.

Serial MR intensity changes of the posterior pituitary in patients with diabetes insipidus after transsphenoidal surgery for pituitary adenomas: report of two cases

This is the first report describing magnetic resonance (MR) intensity changes of the posterior pituitary gland in the patients suffering from the classical "triphasic" diabetes insipidus (DI) after transsphenoidal surgery for pituitary adenomas. A 21-year-old female and a 54-year-old female were admitted to our hospital with the diagnosis of Cushing's disease and acromegaly due to pituitary microadenomas, respectively. No evidence of DI was found, and T1-weighted MR images exhibited "bright spot" corresponding to the posterior pituitary in both cases. Both experienced the classical "triphasic" pattern of water metabolism disturbance after successful transsphenoidal resection of pituitary adenomas, that is, polyuria-oliguria-polyuria. The MR signal hyperintensity in posterior pituitary was detected during the first polyuric phase, but the hyperintensity disappeared during the second polyuric phase. In addition, "bright spot" was restored along with the recovery from DI in the chronic phase. These findings of serial MR images supported that the first DI phase of the classical triphasic course of water metabolism disturbance was caused by secretional dysfunction of stored vasopressin from the posterior gland, whereas the second DI phase was due to impairment in the functional integrity producing vasopressin-containing granules after depletion of vasopressin in the oliguric phase.

A case of lymphocytic infundibuloneurohypophysitis associated with systemic lupus erythematosus

A 27-year-old man was admitted to our hospital with facial erythema and general malaise. He had previously suffered from orbital myositis, central diabetes insipidus (DI), peripheral neuritis, and hypogonadotropic hypogonadism. Physical and immunological examinations revealed that he was suffering from systemic lupus erythematosus (SLE). Magnetic resonance imaging of the hypothalamic-pituitary region demonstrated a significant enlargement of the pituitary stalk and posterior pituitary. Endocrinological examinations showed that he had not only DI and hypogonadotropic hypogonadism but also hypoadrenalism and hypothyroidism, which were ascribed to the pituitary stalk lesion. Lymphocytic infundibuloneurohypophysitis associated with SLE was diagnosed. Administration of 30 mg/day of prednisolone for one month resulted in a marked reduction of the pituitary stalk thickening and posterior pituitary. It is recommended that a pharmacological dose of glucocorticoid be used in the treatment of lymphocytic hypophysitis patients who show significant thickening of the pituitary stalk and/or a large pituitary mass.

Isolated GH deficiency (IGHD) type II: imaging of the pituitary gland by magnetic resonance reveals characteristic differences in comparison with severe IGHD of unknown origin

OBJECTIVE

To determine the specific morphology of the pituitary gland in children with severe isolated GH deficiency due to GH-1 gene mutations (IGHD type II).

DESIGN

The pituitary gland morphology in magnetic resonance imaging (MRI) of children with IGHD type II was analyzed and compared with the findings in a group of children with comparably severe IGHD of unknown origin. In addition, the birth histories of both groups were studied.

SUBJECTS

Thirteen children with IGHD type II were diagnosed in seven European children's hospitals and they carried a corresponding GH-1 gene mutation. For comparison, we selected from a group of 66 MRI-studied GH-insufficient subjects diagnosed in our clinic, all children with severe IGHD (all GH peaks <4 microg/l) who had no GH-1 gene mutation, no first-grade relative with IGHD and no septo-optic dysplasia.

METHODS

Sagittal and coronal images of the brain were analyzed for the presence of any malformation of the pituitary gland and the intracranium. The height of each adenohypophysis was measured in a strict midline sagittal image for quantification of the gland's size. In addition, patients' files were reviewed for birth trauma or breech delivery.

RESULTS

Normal MRI morphology of the pituitary gland was observed in all patients of the familial IGHD type II group (P<0.003) in which, however, five of thirteen patients (38%) exhibited a mild hypoplasia of their gland (mean sagittal adenohypophysial height -1.0+/-0.03 SD score (SDS)). In contrast, the pituitary gland in the idiopathic group showed a definitive malformation with hypoplasia of pituitary stalk and adenohypophysis in all cases, while ectopia of the neurohypophysis was present in nine of the ten cases. The adenohypophysis was significantly smaller in the idiopathic group (mean sagittal adenohypophysial height -3.2+/-0.3 SDS) (P<0.0001). All thirteen birth histories in the familial group (IGHD type II) were unremarkable while, in the idiopathic group, three of eight available birth histories recorded a breech delivery or traumatic birth (37.5%) (P<0.05).

CONCLUSIONS

This study shows for the first time that MRI pituitary morphology may correlate with the etiology of severe IGHD: normal morphology suggests the presence of GH-1 gene mutations, while severe hypoplasia with malformation have other causes which might include so far unknown genetic defects as well as traumatic insults.

Pituitary magnetic resonance imaging and function in patients with growth hormone deficiency with and without mutations in GHRH-R, GH-1, or PROP-1 genes

Pituitary stalk interruption and ectopic posterior lobe on magnetic resonance imaging (MRI) are frequently observed in patients with GH deficiency (GHD), but their pathogenesis remains controversial. We performed pituitary stimulation tests, MRI, and studied GH-1, GHRH receptor (GHRH-R), and Prophet of Pit-1 (PROP-1) genes in 76 patients with GHD. Of 33 patients with isolated GHD, 4 had GH-1 deletions and 4 had GHRH-R mutations; of 43 patients with combined pituitary hormone deficiency, 1 had PIT-1 and 5 had PROP-1 mutations. Compared with the 62 patients without mutations, 14 patients with mutations had higher frequency of consanguinity (57 vs. 2%, P < 0.001), familial cases (21 vs. 3%, P < 0.05), and lower frequency of breech delivery or hypoxemia at birth (0 vs. 39%, P < 0.005). On MRI, all patients with mutations had an intact stalk, whereas it was interrupted or thin in 74% without mutations (P < 0.001). The posterior pituitary lobe was in normal position in 92% of patients with mutations against 13% without mutations (P < 0.001). Among patients with combined pituitary hormone deficiency, hormonal deficiencies were of pituitary origin in all with PROP-1 and PIT-1 mutations and suggestive of hypothalamic origin in 81% without mutations. Perinatal insults were associated with thin/interrupted pituitary stalk, ectopic posterior lobe, and hypothalamic origin of hormonal deficiencies. In contrast, GH-1, GHRH-R, and PROP-1 mutations were associated with consanguineous parents, intact pituitary stalk, normal posterior lobe, and pituitary origin of hormonal deficiencies. We conclude that pituitary MRI and hormonal response to stimulation tests are useful in selection of patients and candidate genes to elucidate the etiological diagnosis of GHD.

[Infundibulitis, an unusual case of central diabetes insipidus]

We report the case of a 53 year old patient who was admitted with polyuria, polydipsia associated with fatigue, depression and sexual dysfunction. Central diabetes insipidus with hypogonadotrophic hypogonadism was diagnosed by a water restriction test and different static and dynamic hormonal dosages. Nodular thickening of the pituitary stalk was noted on the MRI and the biopsy permitted a histological diagnosis of infundibulitis.

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.

Ectopic posterior pituitary lobe and periventricular heterotopia: cerebral malformations with the same underlying mechanism?

BACKGROUND AND PURPOSE

Ectopic posterior pituitary lobe often occurs in children with growth hormone deficiency and is part of the spectrum associated with septo-optic dysplasia. Some cases of septo-optic dysplasia are caused by homozygous mutations in the homeobox gene HESX1, whereas heterozygous mutations are associated with milder phenotypes. To date, HESX1 is the only gene associated with ectopic posterior pituitary lobe. We describe an association between ectopic posterior pituitary lobe and periventricular heterotopia in four children without classic features of septo-optic dysplasia and suggest possible mechanisms on the basis of a review of pituitary embryology and recent molecular genetic advances.

METHODS

Among 20 children with ectopic posterior pituitary lobe, four had associated periventricular heterotopia. We herein review the clinical and MR imaging findings of these four children. Mutation screening of HESX1 was performed in two.

RESULTS

All four children had growth hormone deficiency. None had visual or neurologic disturbances. MR images showed a range of pituitary appearances, with scattered discrete periventricular heterotopia in each case. Other abnormalities were limited to small suprasellar lipomas and callosal dysgenesis. A heterozygous HESX1 mutation was present in one case.

CONCLUSION

The coexistence of ectopic posterior pituitary lobe and periventricular heterotopia suggests they have a common underlying genetic basis that is due to gene expression at different locations and stages of development. The presence of a heterozygous HESX1 mutation in one case suggests this gene is important in the development of both ectopic posterior pituitary lobe and periventricular heterotopia and supports their place in the spectrum of septo-optic dysplasia. Further analysis of HESX1 and other genes in related developmental pathways will elucidate their roles in the development of both malformations.

Pituicytomas, a mis-diagnosed benign tumor of the neurohypophysis: report of three cases

Pituicytoma is a rare benign primary tumor of the neurohypophysis, occurring in the sellar and suprasellar spaces. We report here three new cases with immunohistochemical and electron microscopic study. Particular attention was paid to the expression of some cell adhesion molecules. These tumors were characterized by bundles of elongated cells strongly immunoreactive to anti-vimentin, S-100 protein, neural cell adhesion molecule and neuron-specific enolase antibodies. Glial fibrillary acidic protein (GFAP) was not recorded. It expressed the very late antigen alpha2 (VLAalpha2), but not VLAalpha5, and lacked epithelial markers expression (epithelial membrane antigen, E-cadherin), and specific neuronal markers (synaptophysin, chromogranin, neurofilament). Staining for pituitary hormones was negative. At the ultrastructural level, tumor/blood vessel basal lamina and cytoplasmic intermediate filaments were observed but desmosome or pericellular basal lamina were lacking. In one case few secretory granules were recorded. Differential diagnoses include granular cell tumors, pilocytic astrocytomas and spindle cell tumors such as solitary fibrous tumors, fibroblastic meningiomas and schwannomas. However, the unique pattern of antigenic expression and ultrastructural features of pituicytomas distinguish this rare tumor. As a subpopulation of pituicytes (which are distinctive glial cells of the neurophypophysis), some pituicytomas do not expressed GFAP. This suggests that pituicytomas presumably arise from pituicytes at various stages of their differentiation.

Pituitary apoplexy in association with lymphocytic hypophysitis

Pituitary apoplexy has been recognised much more frequently since the introduction of CT and MRI scanning. Lymphocytic hypophysitis has been increasingly diagnosed in recent years. A case of pituitary apoplexy occurring in a patient with lymphocytic hypophysitis as part of a polyglandular syndrome is reported. This combination does not appear to have been previously reported. The pituitary haemorrhage was confirmed on MRI and at surgery. Lymphocytic hypophysitis was confirmed histologically. The apoplexy was accompanied by severe headache, elevation of the optic chiasm, developing field loss and onset of ptosis. The apoplexy was precipitated by neck extension.