Imaging in malignant germ cell tumors involving the hypothalamo-neurohypophyseal axis: the evaluation of the posterior pituitary bright spot is essential.

PURPOSE: Malignant intracranial germ cell tumors (GCTs) are rare diseases in Western countries. They arise in midline structures and diagnosis is often delayed. We evaluated imaging characteristics and early tumor signs of suprasellar and bifocal GCT on MRI. METHODS: Patients with the diagnosis of a germinoma or non-germinomatous GCT (NGGCT) who received non-contrast sagittal T1WI on MRI pre-therapy were included. Loss of the posterior pituitary bright spot (PPBS), the expansion and size of the tumor, and the expansion and infiltration of surrounding structures were evaluated. Group comparison for histologies and localizations was performed. RESULTS: A total of 102 GCT patients (median age at diagnosis 12.3 years, range 4.4-33.8; 57 males; 67 in suprasellar localization) were enrolled in the study. In the suprasellar cohort, NGGCTs (n = 20) were noticeably larger than germinomas (n = 47; p < .001). Each tumor showed involvement of the posterior lobe or pituitary stalk. A PPBS loss (total n = 98) was observed for each localization and entity in more than 90% and was related to diabetes insipidus. Osseous infiltration was observed exclusively in suprasellar GCT (significantly more frequent in NGGCT; p = .004). Time between the first MRI and therapy start was significantly longer in the suprasellar cohort (p = .005), with an even greater delay in germinoma compared to NGGCT (p = .002). The longest interval to treatment had circumscribed suprasellar germinomas (median 312 days). CONCLUSION: A loss of the PPBS is a hint of tumor origin revealing small tumors in the neurohypophysis. Using this sign in children with diabetes insipidus avoids a delay in diagnosis.

3D fat-suppressed T1-weighted volume isotropic turbo spin-echo acquisition (VISTA) imaging for the evaluation of the ectopic posterior pituitary gland.

OBJECTIVE: We evaluated the usefulness of fat-suppressed three-dimensional T1-weighted volume isotropic turbo spin-echo acquisition (FS 3D T1W-VISTA) imaging for the evaluation of the ectopic posterior pituitary gland (EPPG). MATERIALS AND METHODS: This retrospective study included 9 patients with EPPG due to causes other than tumor. All underwent sagittal two-dimensional (2D) T1W-, FS 3D T1W-VISTA- (VISTA), and 3D T2W-driven equilibrium radiofrequency reset pulse (DRIVE) imaging. Two radiologists independently reviewed the 2D T1W- and VISTA images for their image quality and for visualization of the EPPG and of pituitary stalk transection. DRIVE findings were used as the reference standard for pituitary stalk transection. Interobserver and intermodality agreements were evaluated with the kappa (κ) coefficient. The mean grade assigned to the 2D T1W- and the VISTA imaging technique for visualization of the EPPG was assessed by the Mann-Whitney U test. RESULTS: Interobserver agreement for visualization of the EPPG on 2D T1W- and VISTA images was excellent (κ = 0.82 and κ = 1.00, respectively). The mean grade for EPPG visualization was significantly higher for VISTA- than 2D T1W images (p = 0.0039). CONCLUSION: FS 3D T1W-VISTA imaging is useful for the evaluation of EPPG. Conventional MRI yields insufficient information for the evaluation of the ectopic posterior pituitary gland (EPPG). The visualization of the EPPG was significantly higher for fat-suppressed three-dimensional T1-weighted volume isotropic turbo spin-echo acquisition (FS 3D T1W-VISTA) than 2D T1W images. FS 3D T1W-VISTA imaging is useful for the evaluation of the EPPG.

A rare case report of pituicytoma with biphasic pattern and admixed with scattered Herring bodies.

BACKGROUND: Pituicytoma is a rare pituitary non-neuroendocrine tumour. The awareness of pituitary non-neuroendocrine tumours has gradually increased over the past several decades, but the knowledge of some histological variants of the tumours is limited, particularly in clinicopathological significance. Here, we report a rare case of pituicytoma variant. CASE PRESENTATION: A 71-year-old man presented with sudden symptoms of stroke including urinary incontinence, weakness in right lower limb, and trouble speaking. Physical examinations showed a right facial paralysis. The radiological examinations eventually found a 1.7 × 1.4 × 1.3 cm sellar occupied lesion. After symptomatic treatment improved the symptoms, the patient underwent transsphenoidal resection of the pituitary mass. Histologically, the tumour contained hypocellular area and hypercellular area. The hypocellular area showed elongated spindle cells arranged in a fascicular pattern around small vessels and scattered Herring bodies; the hypercellular area showed a large number of pseudorosettes. Immunohistochemistrically, the tumour cells were positive for thyroid transcription factor-1, S100, and neuron-specific enolase. Neurofilament only showed a little positive in the hypocellular area, and silver impregnation was only noted in a perivascular distribution. The patient had no recurrence 4 months after the surgery. CONCLUSIONS: The rare variant of pituicytoma has a favourable prognosis. Moreover, it needs to be distinguished pituicytomas with pseudorosettes from ependymomas because of different prognosis. Lastly, Herring bodies may occasionally be seen in the pituicytoma, which could be a potential diagnostic pitfall.

A recurrent case of pituicytoma 16 years later.

BACKGROUND: Pituicytoma is a rare; slow-growing primary tumour originating from the glial cells of the neurohypophysis. It was classed as a low-grade (grade I) central nervous system tumour by the World Health Organization in 2007. We present the case of a 71-year-old man with a previous history of sellar meningioma who underwent surgical resection of pituicytoma by transphenoidal hypophysectomy. METHOD: We conducted a literature search using Medline EMBASE and the Cochrane Database of Systematic Reviews using the Ovid search engines. Key words searched were 'pituitary gland', 'pituicytoma', 'neurohypophysis'. Patient records and imaging were obtained from the Royal Stoke University Hospital database. RESULTS: A 71-year-old man with a background of sellar meningioma 16 years previously was found to have a pituitary fossa tumour on surveillance magnetic resonance imaging. Differential diagnosis was pituitary adenoma. Endoscopic transphenoidal hypophysectomy was performed. Histology was consistent with pituicytoma. As a result of this histology from his initial tumour was re-examined and was amended to pituicytoma, indicating a recurrence. CONCLUSION: Pituicytoma is a benign, slow growing lesion of the posterior pituitary. Brat et al diagnosed it as a distinct entity in 2000 and it was listed as a World Health Organization classification grade I tumour in 2007. It can be mistaken for pituitary adenoma owing to its similar clinical presentation. Complete excision of the tumour by transphenoidal hypophysectomy is an effective management for pituicytoma as demonstrated in this case.

A new imaging entity consistent with partial ectopic posterior pituitary gland: report of six cases.

BACKGROUND: Abnormal posterior pituitary development including ectopic location has been associated with endocrine manifestations of anterior pituitary dysfunction. OBJECTIVE: We describe an unreported clinical and radiologic entity we call partial ectopic posterior pituitary for which associated endocrine consequences are not known. MATERIALS AND METHODS: We selected pediatric head MRI examinations from 2005 to 2017 based on the finding of a double midline sellar and suprasellar bright spot on T1-weighted sequence. Medical history, physical examination, pituitary hormonal profile and bone age evaluation were extracted from the medical record of the selected patients. An experienced pediatric neuroradiologist reviewed head MRIs, which were performed on 3-tesla (T) magnet and included at least sagittal T1-weighted imaging centered on the sella turcica obtained with and without fat suppression. RESULTS: In six cases, two midline bright spots were identified on T1-weighted sequences obtained both with and without fat suppression. While one spot was located at the expected site of the neurohypophysis in the posterior sella, the second one was in the region of the median eminence, suggesting partial ectopic posterior pituitary gland. Growth hormone deficiency, either isolated (n=1) or combined with thyroid stimulating hormone deficiency (n=1) was found. None of the children had clinical signs of posterior pituitary dysfunction. CONCLUSION: We describe an unreported imaging entity suggesting partial ectopic posterior pituitary gland in six children. Anterior pituitary hormone deficiencies might be detected in those children and long-term follow-up could provide additional information on the development of other pituitary hormone deficiencies.

Locations, associations and temporal evolution of intracranial arterial infundibular dilatations in children.

BACKGROUND: There are few data in the literature on the characteristics and natural history of intracranial arterial infundibular dilatations in children. METHODS: An institutional review board-approved retrospective review was performed of infundibula reported on MR angiography in patients <18 years of age at our tertiary pediatric institute from 1998 to 2016. Clinical data (age, sex, diagnosis, other vascular variants/pathologies) were recorded and images assessed for vessel of origin, infundibulum size and exact location. Ratios of infundibulum:parent artery were assessed at diagnosis and last follow-up. Temporal evolution to aneurysm was evaluated. RESULTS: We found 60 intracranial infundibula in 60 children (male:female=27:33; mean age 9.7±5.2 years, range 2-18 years,). Family history of aneurysms was present in 2/60 (3.3%). Syndromic association was found in 14/60 (23.3%), most frequently sickle cell disease (4/14=28.6%). Mean infundibulum size was 2.2±0.5 mm, with mean ratio to parent artery of 0.54±0.17. The most common location was on the P1-posterior cerebral artery (34/63=56.7%), whereas posterior communicating infundibula were seen in only 4/60 (6.7%) cases. Other cerebrovascular variants were seen in 12/60 (20%) patients. On follow-up imaging (in 32/60 patients over 86 patient-years, mean 32.3±35.7 months), no significant change in infundibulum:parent artery ratio was noted. None of the infundibular dilatations showed interval evolution to aneurysm. CONCLUSION: We present the largest reported cohort of pediatric intracranial arterial infundibula, which we found to be distinct from their adult counterparts with regard to location, etiology and temporal evolution. Growth over time and/or aneurysmal formation are rare, not necessitating frequent short-term imaging surveillance during childhood.

Imaging Characteristics of a Hypervascular Pituitary Spindle Cell Oncocytoma on Magnetic Resonance Imaging and Digital Subtraction Angiography.

BACKGROUND: Spindle cell oncocytomas (SCOs) are rare neuroendocrine tumors of the posterior pituitary that are often misdiagnosed as nonfunctional pituitary tumors. Fewer than 50 cases of SCOs have been described in the literature, and many of these reports have documented the tumors to be hypervascular on imaging or histology. CASE DESCRIPTION: We present the first cerebral angiography imaging findings of an SCO before primary resection. The discovery of a prominent tumor blush, enlarged meningohypophyseal feeders bilaterally, and prominent tumor draining veins aided in preoperative planning and subsequent successful endoscopic transsphenoidal surgical resection. CONCLUSIONS: Despite being a rare entity, SCOs should be included in the differential diagnosis when working up a hypervascular sellar tumor. Flow voids may be present on initial magnetic resonance imaging evaluation. Subsequent digital subtraction angiography can be used to further investigate abnormal vasculature and aid in surgical planning.

Pituicytoma Associated with Acromegaly and Cushing Disease.

BACKGROUND: Pituicytoma is a rare neoplasm arising in the sellar region (World Health Organization grade I). Clinically, pituicytomas mimic nonfunctioning pituitary macroadenomas and are occasionally incidentally discovered at autopsy. Pituitary adenomas can occur with other sellar pathologies, and the term "collision sellar lesions" has been coined for this rare entity. There have only been a few reports of the coexistence of pituicytoma and pituitary adenoma. We present 2 cases of pituicytoma coexisting with acromegaly and Cushing disease. CASE DESCRIPTION: Case 1: A 29-year-old woman had acromegaly. The macroadenoma was partially removed in her first surgery; thus an endonasal reoperation was required for debulking and posterior radiosurgery. Pituicytoma coexisting with somatotropinoma was diagnosed on pathologic examination. Case 2: A 33-year-old woman had adrenocorticotropic hormone-dependent Cushing disease. She underwent endonasal resection. Undetectable postoperative cortisol levels provided evidence that the underlying adrenocorticotropic hormone source was successfully removed. On the basis of morphologic features and the immunohistochemical profile, pituicytoma was diagnosed on pathologic examination. Pituitary adenoma was not confirmed histologically in this patient. CONCLUSIONS: Only 117 cases of pituicytoma have been reported since it was first described in 1955. Before our report, only 5 cases of patients with pituicytoma coexisting with pituitary adenoma had been described. The coexistence of these 2 entities may not just be a mere coincidence but may be due to a yet unknown pathophysiologic link or common progenitor lineage of both lesions. Association between pituicytoma and pituitary adenoma is increasingly being reported.

Combined Pituitary Hormone Deficiency Caused by a Synonymous HESX1 Gene Mutation.

CONTEXT: Mutations in the HESX1 gene can give rise to complex phenotypes that involve variable pituitary hormone deficiencies and other developmental defects. CASE DESCRIPTION: A 14-year-old boy presented with short stature and delayed puberty and received a diagnosis of GH deficiency, central hypothyroidism, hypogonadotropic hypogonadism, and secondary adrenal insufficiency. He had anterior pituitary hypoplasia, ectopic posterior pituitary, and an interrupted pituitary stalk. Genetic studies uncovered a heterozygous variant in exon 2 of the HESX1 gene (c.219C>T; p.Ser73Ser). This single base change was predicted to be synonymous at the translational level but was shown to cause skipping of exon 2 in the RNA transcript. CONCLUSIONS: This study of a patient with combined pituitary hormone deficiency revealed an unusual synonymous mutation of the HESX1 gene leading to abnormal RNA processing and indicates the importance of investigating silent variants that at first glance appear to be benign.

Granular Cell Tumor of the Neurohypophysis: 3 Cases and a Systematic Literature Review of 98 Cases.

BACKGROUND: Granular cell tumors (GCTs) of the neurohypophysis are rare neoplastic diseases of the pituitary. Because of the rare nature of the disease, previous descriptions have been limited to single-case studies, small series, or simple reviews. METHODS: We reported 3 cases in our medical center and systematically reviewed 98 cases who met inclusion criteria. Data were gathered on different aspects of GCTs' characteristics, including demographics, clinical features, laboratory features, histological features, immunocytochemical features, radiologic features, and treatment to elucidate any associations useful in determining pathogenesis and appropriate treatment. RESULTS: Female sex was significantly associated with GCTs (P < 0.001). The most common presenting symptom and tentative diagnosis were ophthalmologic defects in 61.2% and pituitary adenoma preoperatively in 18.4%, respectively. Most neurohypophysial GCTs possess immunopositivity for S-100 protein (59.1%, 26/44) and negative staining for glial fibrillary acidic protein (69.8%, 30/43). CONCLUSIONS: These findings lend strong support to the suggestion that tumors probably remain in the transitional cell type. To our knowledge, our systematic review presents the largest number of symptomatic cases ever enumerated, with 98 cases meeting the inclusion criteria.

Low-Grade Glioma of the Neurohypophysis: Clinical Characteristics and Surgical Outcomes.

BACKGROUND: Low-grade glioma (LGG) of the neurohypophysis is an extremely rare tumor arising from the pituicytes of the posterior pituitary or the infundibulum. The preoperative imaging findings of these tumors mimic those of pituitary adenomas, and radical resection is often challenging in affected patients due to the hypervascularity of the tumor. Here we describe the clinical and radiologic features of this clinical entity. METHODS: We identified 8 patients with LGG of the neurohypophysis who underwent surgery at Toranomon Hospital between January 2007 and March 2017. We retrospectively reviewed the clinical and radiologic data for these patients. RESULTS: The patient cohort comprised 5 men and 3 women, with a mean age of 57 years. The presenting symptoms included visual disturbance in 7 patients and anterior pituitary dysfunction in 7 patients. No patient had diabetes insipidus (DI). Preoperative magnetic resonance imaging (MRI) showed a thick anterior pituitary gland located anterior to the tumor in 3 patients and flow voids on T2-weighted images in 6 patients. All patients underwent transsphenoidal surgery, and gross total resection was achieved in 4 patients. Postoperative morbidities included deterioration of anterior pituitary function in 4 patients and permanent DI in 3 patients. CONCLUSIONS: Anterior displacement of a thick anterior pituitary by a tumor combined with evidence of flow voids on preoperative MRI is helpful in the preoperative diagnosis of LGG of the neurohypophysis. Radical resection should be attempted in these tumors, especially during primary surgery, even though it is associated with postoperative pituitary dysfunction.

Clinical and imaging features of granular cell tumor of the neurohypophysis: A retrospective analysis.

The aim of this study was to explore x-ray computed tomography (CT) and magnetic resonance imaging (MRI) characteristics specific to granular cell tumors (GCTs) of the neurohypophysis.The clinical and imaging data of 6 patients with operation-proven GCTs of the neurohypophysis were analyzed retrospectively.There were 6 patients with GCTs of the neurohypophysis confirmed pathologically. Five of the tumors were purely suprasellar lesions distinct from the intrasellar pituitary gland. One tumor was both intra- and suprasellar. Solid tumors were hyperattenuated and enhanced homogeneously on CT, while showing isointensity on T1WI and heterogeneous hypointensity on T2WI, with homogeneous (4/5) or inhomogeneous (1/5) enhancement. The cystic tumor showed hypointensity on T1WI and hyperintensity on T2WI, with ring enhancement. "Star-like crack sign" was seen in 2 larger solid cases. Calcification was absent in all cases.Well-circumscribed intra and/or suprasellar masses, hyperattenuated and homogeneously enhancing on CT, hypointensity on T2WI, rarely seen calcification, should arouse suspicion of GCTs of the neurohypophysis.

Presence of the posterior pituitary bright spot sign on MRI in the general population: a comparison between 1.5 and 3T MRI and between 2D-T1 spin-echo- and 3D-T1 gradient-echo sequences.

PURPOSE: To describe the prevalence of the posterior pituitary bright spot (PPBS) in the general population on 1.5 and 3T MRI examinations and on 2D-T1 spin-echo (SE) and 3D-T1 gradient-echo (GE) sequences. MATERIALS AND METHODS: 1017 subjects who received an MRI of the brain for aspecific neurological complaints were included. MRI was performed on 1.5T in 64.5% and on 3T in 35.5% of subjects. Presence of the PPBS was evaluated on sagittal 2D T1-SE echo images with slice thickness 3 mm in 67.5% and on sagittal 3D T1-GE with slice thickness 0.9 mm in 32.5% of subjects. RESULTS: The PPBS was detectable in 95.9% of subjects. After correction for sex and age, no statistically significant difference could be seen concerning PPBS detection between 1.5 and 3T MRI examinations (p = 0.533), nor between 2D T1-SE and 3D T1-GE sequences (p = 0.217). There was a statistically significant association between increasing age and the absence of the PPBS (p < 0.001). The PPBS could not be identified in 6.2% of male subjects, compared to 2.2% of female subjects (p = 0.01). DISCUSSION: Absence of the PPBS can be seen in 4.1% of patients undergoing MRI of the brain for non-endocrinological reasons. Neither field-strength nor the use of a thick-sliced 2D T1-SE versus a thin-sliced 3D T1-GE sequence influenced the detectability of the PPBS. There is a statistically significant association between increasing age and male sex and the absence of the PPBS.

Hyponatremia with Loss of High Signal Intensity in the Posterior Pituitary Lobe on T1-weighted Magnetic Resonance Imaging.

Herein, we report on an 82-year-old woman who presented with anorexia. The patient had hyponatremia with preserved urinary osmotic pressure. T1-weighted magnetic resonance imaging (MRI) showed a lack of high signal intensity (SI) in the posterior pituitary lobe. Based on the patient's high levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP), heart failure was suspected. The heart failure may have caused arginine vasopressin (AVP) secretion. The depletion of AVP secretory granules may therefore cause the posterior pituitary gland to disappear on T1-weighted MRI.

Recurrent Pituicytoma with Pseudoaneurysm: Report of a Challenging Case.

BACKGROUND: Pituicytoma is a rare tumor originating from glial cells of the adult neurohypophysis and infundibulum. Surgical removal is the treatment of choice for this neoplasm. In recent years the endoscopic endonasal approach has proven to be a viable and effective alternative to standard craniotomy. CASE DESCRIPTION: We report a case of a patient submitted to surgical treatment for a recurrence of pituicytoma, which was operated on transcranially at another hospital approximately 5 years previously. After transcranial surgery, the patient developed a symptomatic recurrence and an undisclosed intrasellar pseudoaneurysm that were treated with an endoscopic endonasal approach, but still required an intracranial approach to complete the resection. CONCLUSIONS: An intrasellar pseudoaneurysm can endanger the endoscopic removal of the pituicytoma, forcing the surgeon to reevaluate a microscopic transcranial approach or to consider a staged procedure.

Bilateral Optic Disc Pits With Posterior Pituitary Ectopia.

Posterior pituitary ectopia has been reported previously in association with optic nerve hypoplasia, as a variant of septo-optic dysplasia. We describe a 14-year-old boy with posterior pituitary ectopia and bilateral optic disc pits. He had hypopituitarism and a reduction in visual acuity to 20/40 in each eye, owing to loss of foveal ganglion cells. Optic pits and posterior pituitary ectopia may have occurred together in the same subject by chance, but the rarity of both conditions suggests a possible association.

High-resolution heavily T2-weighted magnetic resonance imaging for evaluation of the pituitary stalk in children with ectopic neurohypophysis.

BACKGROUND: In anterior pituitary deficiency, patients with non visible pituitary stalk have more often multiple deficiencies and persistent deficiency than patients with visible pituitary stalk. OBJECTIVE: To compare the diagnostic value of a high-resolution heavily T2-weighted sequence to 1.5-mm-thick unenhanced and contrast-enhanced sagittal T1-weighted sequences to assess the presence of the pituitary stalk in children with ectopic posterior pituitary gland. MATERIALS AND METHODS: We retrospectively evaluated the MRI data of 14 children diagnosed with ectopic posterior pituitary gland between 2010 and 2014. We evaluated the presence of a pituitary stalk using a sagittal high-resolution heavily T2-weighted sequence and a 1.5-mm sagittal T1-weighted turbo spin-echo sequence before and after contrast medium administration. RESULTS: A pituitary stalk was present on at least one of the sequences in 10 of the 14 children (71%). T2-weighted sequence depicted the pituitary stalk in all 10 children, whereas the 1.5-mm-thick T1-weighted sequence depicted 2/10 (20%) before contrast injection and 8/10 (80%) after contrast injection (P=0.007). CONCLUSION: Compared with 1.5-mm-thick contrast-enhanced T1-weighted sequences, high-resolution heavily T2-weighted sequence demonstrates better sensitivity in detecting the pituitary stalk in children with ectopic posterior pituitary gland, suggesting that contrast injection is unnecessary to assess the presence of a pituitary stalk in this setting.

The Missing Link: A Case of Absent Pituitary Infundibulum and Ectopic Neurohypophysis in a Pediatric Patient with Heterotaxy Syndrome.

We report a case of absent pituitary infundibulum and ectopic neurohypophysis in a 4-year-old patient presenting clinically with hypopituitarism as well as heterotaxy syndrome complicated by global developmental delay and growth retardation. The clinical and laboratory workup of our patient suggested underlying hypopituitarism related to either congenital or acquired pathology, necessitating MRI to distinguish between them. We explain the various structural causes of hypopituitarism and detail how to predict the MRI findings and treatment, based on a fundamental understanding of the anatomy and pathophysiology of the hypothalamic pituitary axis and distinguishing anterior versus posterior pituitary hormone derangements. We also discuss two important theories widely acknowledged in the literature to explain congenital hypopituitarism: 1. Head trauma typically during birth resulting in a stretch injury to the infundibulum. 2. Congenital fetal maldevelopment of midline structures.

Patient With Severe Hyponatremia Caused by Adrenal Insufficiency Due to Ectopic Posterior Pituitary Lobe and Miscommunication Between Hypothalamus and Pituitary: A Case Report.

Hyponatremia may be one of the clinical manifestations of adrenal insufficiency (AI) and during the diagnostic workup of hyponatremic patients investigation of AI should be included.We report the case of an 82-year-old patient who was admitted to our hospital with clinical symptoms and laboratory findings of hyponatremia. Following the diagnostic algorithm of hyponatremia we reached the diagnosis of AI. Clinician's attention must focus on the underlying cause of AI which in this case was hidden in a miscommunication between hypothalamus and pituitary due to an ectopic posterior pituitary lobe and became apparent by a pituitary magnetic resonance imaging (MRI) scan. Treatment with oral hydrocortisone resulted in full clinical recovery and electrolyte balance, which was maintained after 7 months of follow-up.Secondary AI is related with hyponatremia through increased ADH secretion. Although a hyponatremic episode may be the first presentation of AI, clinical suspicion is of high importance in order to place the right diagnosis. Disruption of communication between hypothalamus and pituitary is a rare but considerable cause of AI.