Granular cell tumor of the neurohypophysis presenting as a third ventricle mass.

Granular cell tumors of the neurohypophysis (GCT) are rare benign neoplasms belonging, along with pituicytoma and spindle cell oncocytoma, to the family of TTF1-positive low-grade neoplasms of the posterior pituitary gland. GCT usually present as a solid sellar mass, slowly growing and causing compressive symptoms over time, occasionally with suprasellar extension. They comprise polygonal monomorphous cells with abundant granular cytoplasm, which is ultrastructurally filled with lysosomes. Here we report the case of a GCT presenting as a third ventricle mass, radiologically mimicking chordoid glioma, with aberrant expression of GFAP and Annexin-A, which lends itself as an example of an integrated diagnostic approach to sellar/suprasellar and third ventricle masses.

A procedure in mice to obtain intact pituitary-infundibulum-hypothalamus preparations: a method to evaluate the reconstruction of hypothalamohypophyseal system.

PURPOSE: The histopathological study of brain tissue is a common method in neuroscience. However, efficient procedures to preserve the intact hypothalamic-pituitary brain specimens are not available in mice for histopathological study. METHOD: We describe a detailed procedure for obtaining mouse brain with pituitary-hypothalamus continuity. Unlike the traditional methods, we collect the brain via a ventral approach. We cut the intraoccipital synchondrosis, transection the endocranium of pituitary, broke the spheno-occipital synchondrosis, expose the posterior edge of pituitary, separate the trigeminal nerve, then the intact pituitary gland was preserved. RESULT: We report an more effective and practical method to obtain continuous hypothalamus -pituitary preparations based on the preserve of leptomeninges. COMPARED WITH THE EXISTING METHODS: Our procedure effectively protects the integrity of the fragile infundibulum preventing the pituitary from separating from the hypothalamus. This procedure is more convenient and efficient. CONCLUSION: We present a convenient and practical procedure to obtain intact hypothalamic-pituitary brain specimens for subsequent histopathological evaluation in mice.

Spindle cell oncocytoma of the neurohypophysis with metastasis to the sphenoparietal sinus and immunohistochemical negativity for S100 and epithelial membrane antigen (EMA).

We report the case of a 61-year-old male with spindle cell oncocytoma of the hypophysis. On presentation to the Department of Neurosurgery at the German Armed Forces Hospital of Ulm, the patient reported a history of several years of left sixth nerve palsy, right ptosis, increased sensitivity to light, and a bilateral retrobulbar pressure sensation. Pituitary function was normal. A chromophobe non-functioning pituitary adenoma was initially suspected. The diagnosis was established on the basis of examination at a histopathology reference laboratory using immunohistochemistry to identify cell surface markers. During two years of follow-up, there were two clinical recurrences requiring surgery. To our knowledge, this is the 35th documented case of spindle cell oncocytoma of the pituitary gland and the first that was immunohistochemically negative for epithelial membrane antigen (EMA) and S100; and the first that displayed haematogenous metastasis to the right sphenoparietal sinus. The three surgical procedures were associated with massive intraoperative bleeding and thus resulted in subtotal tumor resection. Following surgery for the recurrences, the patient underwent radiotherapy.

Granular Cell Tumor and Spindle Cell Oncocytoma of the Pituitary Gland: Imaging and Intraoperative Cytology Diagnostic Dilemmas and Management Challenges.

BACKGROUND: Tumors arising from the posterior pituitary gland are rare and closely resemble pituitary adenoma in presentation and imaging. Most of them come as a histopathologic surprise. We have analyzed the posterior pituitary tumors managed in our institute and have discussed the dilemmas in imaging, challenges in intraoperative squash cytology, and surgical management. METHODS: We retrospectively reviewed our operative database of pituitary tumors over the past 10 years, which included five posterior pituitary tumors (three granular cell tumors [GCTs] and two spindle cell oncocytomas [SCOs]). Clinical, imaging, and endocrine characteristics; intraoperative details; histopathologic features; and postoperative outcomes were collected and analyzed. RESULTS: The mean age of the patients was 47 years. All patients presented with varying degrees of vision loss. Radiology revealed a sellar / suprasellar lesion with the pituitary gland seen separately in two of three GCTs, whereas a separate pituitary gland could not be identified in both the SCOs. Pituitary adenoma was a radiologic diagnosis in only two of five cases. Three patients underwent a transsphenoidal surgery, whereas two underwent surgery by the transcranial approach. Intraoperative cytology was challenging, though a possibility of posterior pituitary tumor was considered in three of four cases, whereas one was considered meningioma. All the tumors were very vascular and influenced the extent of resection. CONCLUSIONS: GCTs and SCOs are relatively uncommon tumors that are difficult to diagnose on preoperative imaging. Intraoperative squash cytology too can pose challenges. A preoperative suspicion can prepare the surgeon for surgery of these hypervascular tumors. The transcranial approach may be necessary in cases of uncertainty in imaging.

Comprehensive Genomic Characterization of A Case of Granular Cell Tumor of the Posterior Pituitary Gland: A Case Report.

Granular cell tumors of the pituitary belong to a rare family of neoplasms, arising from the posterior pituitary gland. Although considered benign, they may cause significant morbidity and residual disease after resection can lead to poor clinical outcomes. Currently, there is no known medical therapy for any posterior pituitary gland tumor, in part due to sparse molecular characterization of these lesions. We report data from whole exome sequencing of a case of granular cell tumor of the pituitary, performed under an institutional review board approved protocol. A 77 year-old female underwent resection of an incidentally diagnosed pituitary mass that was causing radiographic compression of the optic nerves with a subclinical temporal field defect and central hypothyroidism. The pathology of the resected specimen demonstrated a granular cell tumor of the posterior pituitary gland. Whole-exome sequencing revealed mutations predicted to be deleterious in key oncogenes, SETD2 and PAX8, both of which have been described in other cancers and could potentially be amenable to targeted therapies with existing approved drugs, including immune checkpoint inhibitors and histone deacetylase inhibitors, respectively. To our knowledge, this is the first comprehensive genomic characterization of granular cell tumor of the posterior pituitary gland. We report mutations in oncogenes predicted to be deleterious and reported in other cancers with potential for therapeutic targeting with existing pharmacologic agents. These data provide new insights into the molecular pathogenesis of GCT of the pituitary and may warrant further investigation.

Co-occurrence of Pituitary Neuroendocrine Tumors (PitNETs) and Tumors of the Neurohypophysis.

Between 1996 and 2020, 12,565 cases were enrolled in the German Registry of Pituitary Tumors including 10,084 PitNETs (10,067 adenomas and 19 carcinomas obtained surgically and 193 adenomas diagnosed at autopsy) as well as 69 spindle cell tumors of the neurohypophysis (64 surgical specimens and 5 autopsies). In six patients (1 post mortem and 5 surgical specimens), PitNETs as well as posterior lobe tumors were found in the specimens. Two of the PitNETs were sparsely granulated prolactin-producing tumors, combined in one case with a granular cell tumor and in one case with a pituicytoma. One of the PitNETs revealed that autopsy was a sparsely granulated GH tumor combined with a neurohypophyseal granular cell tumor. Two PitNETs were null cell adenomas combined with a pituicytoma and a spindle cell oncocytoma, respectively. Further, one Crooke cell tumor was combined with a spindle cell oncocytoma. In five cases, the PitNETs were larger than the posterior lobe tumors and accounted for the clinical symptoms. Previously, four cases of co-existing pituitary anterior and posterior lobe tumors were described in the literature, comprising two ACTH PitNETs, one gonadotrophic PitNET and one null cell PitNET, each in combination with a pituicytoma. PitNETs and concomitant granular cell tumor or spindle cell oncocytoma, as observed in our cohort, have not been reported before.

Neuroendocrine changes in the hypothalamic-neurohypophysial system in the Wistar audiogenic rat (WAR) strain submitted to audiogenic kindling.

The Wistar audiogenic rat (WAR) strain is used as an animal model of epilepsy, which when submitted to acute acoustic stimulus presents tonic-clonic seizures, mainly dependent on brainstem (mesencephalic) structures. However, when WARs are exposed to chronic acoustic stimuli (audiogenic kindling-AK), they usually present tonic-clonic seizures, followed by limbic seizures, after recruitment of forebrain structures such as the cortex, hippocampus and amygdala. Although some studies have reported that hypothalamic-hypophysis function is also altered in WAR through modulating vasopressin (AVP) and oxytocin (OXT) secretion, the role of these neuropeptides in epilepsy still is controversial. We analyzed the impact of AK and consequent activation of mesencephalic neurocircuits and the recruitment of forebrain limbic (LiR) sites on the hypothalamic-neurohypophysial system and expression of Avpr1a and Oxtr in these structures. At the end of the AK protocol, nine out of 18 WARs presented LiR. Increases in both plasma vasopressin and oxytocin levels were observed in WAR when compared to Wistar rats. These results were correlated with an increase in the expressions of heteronuclear (hn) and messenger (m) RNA for Oxt in the paraventricular nucleus (PVN) in WARs submitted to AK that presented LiR. In the paraventricular nucleus, the hnAvp and mAvp expressions increased in WARs with and without LiR, respectively. There were no significant differences in Avp and Oxt expression in supraoptic nuclei (SON). Also, there was a reduction in the Avpr1a expression in the central nucleus of the amygdala and frontal lobe in the WAR strain. In the inferior colliculus, Avpr1a expression was lower in WARs after AK, especially those without LiR. Our results indicate that both AK and LiR in WARs lead to changes in the hypothalamic-neurohypophysial system and its receptors, providing a new molecular basis to better understaind epilepsy.

Clinical-Pathological, Immunohistochemical, and Genetic Characterization of a Series of Posterior Pituitary Tumors.

Posterior pituitary tumors are supposed to represent the morphological spectrum of a single entity. Herein, we report the clinical-pathological, immunohistochemical, and genetic features of 5 spindle cell oncocytomas (SCOs), 3 pituicytomas, and 1 granular cell tumor (GCT). SCOs had the highest local invasiveness and affected older subjects. The 3 histotypes differed in the content of spindle cells (predominant in pituicytoma and absent in GCT), presence of lymphocytic infiltrate (in SCO and GCT, but not in the pituicytoma) and EMA/GFAP staining (negative in GCT; EMA-positive/GFAP-negative in 4/5 SCO and GFAP-positive in 3/3 pituicytomas). Three SCOs and 1 pituicytoma analyzed with next-generation sequencing had no mutations in 409 genes. However, 1 SCO had previously unreported homozygous deletion of CDKN2A/B and another of SMARCA4, SMARCB1, and NF2. All 3 SCOs had loss of heterozygosity of chromosome 1p, while the pituicytoma had chromosome 19 homozygous loss and chromosomes 10, 13q, and 18q loss of heterozygosity. Since 1p and 13q losses were previously reported in 1 pituicytoma and 1 SCO, respectively, our data demonstrate that posterior pituitary tumors share common genetic alterations. The possibility that posterior pituitary tumors are SMARCA4/SMARCB1-deficient should be kept in mind in the differential diagnosis toward other entities.

Primary Tumors of the Posterior Pituitary Gland: A Systematic Review of the Literature in Light of the New 2017 World Health Organization Classification of Pituitary Tumors.

OBJECTIVE: The rare clinical entity of primary posterior pituitary tumors (PPTs) includes pituicytomas, granular cell tumors, spine cell oncocytomas, and sellar ependymomas. The recent World Health Organization classification of PPTs based on thyroid transcription factor 1 positivity has led to more investigations into the epidemiology, clinical presentation, nature history, histologic features, and operative characteristics of these tumors. The aim of this review is to summarize the characteristics of primary PPTs. METHODS: Our summary involved an in-depth review of the literature on PPTs. Our systematic review was carried out using the PubMed database and PRISMA guidelines. RESULTS: An initial search identified 282 publications. After strict application of the inclusion criteria, we found 16 articles for case series of patients with primary PPT (N > 5), which were included in our table for literature review. An additional 10 articles were review articles on PPTs published in the last 20 years and were used as resource for our systematic review. An extensive analysis was then performed to extract relevant clinical data with respect to the clinical radiologic histopathologic profile of primary PPTs and their treatment outcome. CONCLUSIONS: Primary PPTs are a rare group of pituicyte-derived low-grade nonneuroendocrine neoplasms that arise from the sellar region. The nondescript radiographic findings and subtle endocrine abnormalities also veil their accurate diagnostic prediction. As shown through the narrative as well as the literature review, there is still a lot to be understood about PPTs. A prospective multicenter registry of these rare tumors would benefit both the neurosurgical as well as the endocrinologic knowledge base.

Acquired forms of central diabetes insipidus: Mechanisms of disease.

Most cases of acquired central diabetes insipidus are caused by destruction of the neurohypophysis by: 1) anatomic lesions that destroy the vasopressin neurons by pressure or infiltration, 2) damage to the vasopressin neurons by surgery or head trauma, and 3) autoimmune destruction of the vasopressin neurons. Because the vasopressin neurons are located in the hypothalamus, lesions confined to the sella turcica generally do not cause diabetes insipidus because the posterior pituitary is simply the site of the axon terminals that secrete vasopressin into the bloodstream. In addition, the capacity of the neurohypophysis to synthesize vasopressin is greatly in excess of the body's needs, and destruction of 80-90% of the hypothalamic vasopressin neurons is required to produce diabetes insipidus. As a result, even large lesions in the sellar and suprasellar area generally are not associated with impaired water homeostasis until they are surgically resected. Regardless of the etiology of central diabetes insipidus, deficient or absent vasopressin secretion causes impaired urine concentration with resultant polyuria. In most cases, secondary polydipsia is able to maintain water homeostasis at the expense of frequent thirst and drinking. However, destruction of the osmoreceptors in the anterior hypothalamus that regulate vasopressin neuronal activity causes a loss of thirst as well as vasopressin section, leading to severe chronic dehydration and hyperosmolality. Vasopressin deficiency also leads to down-regulation of the synthesis of aquaporin-2 water channels in the kidney collecting duct principal cells, causing a secondary nephrogenic diabetes insipidus. As a result, several days of vasopressin administration are required to achieve maximal urine concentration in patients with CDI. Consequently, the presentation of patients with central diabetes insipidus can vary greatly, depending on the size and location of the lesion, the magnitude of trauma to the neurohypophysis, the degree of destruction of the vasopressin neurons, and the presence of other hormonal deficits from damage to the anterior pituitary.

Basophilic invasion in the neurohypophysis is increased in patients with Alzheimer's disease.

PURPOSE: The prevalence of basophilic invasion (BI) and degenerative changes in the neurohypophysis of humans with neurodegenerative disease is not established. MATERIALS AND METHODS: We evaluated 122 pituitary glands reviewed at autopsy including 45 with Alzheimer's disease (AD) Braak and Braak stage V or VI, 18 with Lewy body disease (LBD), and 59 age-matched controls for BI. In addition, pituitary glands from 51 patients including 25 patients with AD and 18 aged-matched controls were studied with a periodic acid Schiff (PAS) stain and immunohistochemistry with a polyclonal antibody to nestin. Samples were graded as negative (0) or positive (1). RESULTS: BI was seen in 35 of 45 patients with AD (0.78 ± 0.06 mean and SE: 78%) and was significantly higher than 30 of 59 controls (0.51 ± 0.07; 51%) (p = 0.0236). BI was seen in 7 of 18 patients with LBD (0.39 ± 0.12; 39%) compared to controls (p = 0.387). BI was also significantly higher in AD compared to LBD (p = 0.0001). Nestin immunoreactivity was detected in the neurohypophysis of all patients. Definite nestin was not found in BI but was seen in Herring body-like structures, in pituicytes and axons. Phospho-τ-immunoreactive Herring bodies were seen in 65% with AD but phospho-τ-immunoreactive neurofibrillary tangles were not found. CONCLUSION: BI is increased in AD compared to controls or LBD but not associated with nestin immunoreactivity. The significance and role of BI as a marker for AD warrants additional study.

Sudden death in epilepsy and ectopic neurohypophysis in Joubert syndrome 23 diagnosed using SNVs/indels and structural variants pipelines on WGS data: a case report.

BACKGROUND: Joubert syndrome (JBTS) is a genetically heterogeneous group of neurodevelopmental syndromes caused by primary cilia dysfunction. Usually the neurological presentation starts with abnormal neonatal breathing followed by muscular hypotonia, psychomotor delay, and cerebellar ataxia. Cerebral MRI shows mid- and hindbrain anomalies including the molar tooth sign. We report a male patient with atypical presentation of Joubert syndrome type 23, thus expanding the phenotype. CASE PRESENTATION: Clinical features were consistent with JBTS already from infancy, yet the syndrome was not suspected before cerebral MRI later in childhood showed the characteristic molar tooth sign and ectopic neurohypophysis. From age 11 years seizures developed and after few years became increasingly difficult to treat, also related to inadequate compliance to therapy. He died at 23 years of sudden unexpected death in epilepsy (SUDEP). The genetic diagnosis remained elusive for many years, despite extensive genetic testing. We reached the genetic diagnosis by performing whole genome sequencing of the family trio and analyzing the data with the combination of one analysis pipeline for single nucleotide variants (SNVs)/indels and one for structural variants (SVs). This lead to the identification of the most common variant detected in patients with JBTS23 (OMIM# 616490), rs534542684, in compound heterozygosity with a 8.3 kb deletion in KIAA0586, not previously reported. CONCLUSIONS: We describe for the first time ectopic neurohypophysis and SUDEP in JBTS23, expanding the phenotype of this condition and raising the attention on the possible severity of the epilepsy in this disease. We also highlight the diagnostic power of WGS, which efficiently detects SNVs/indels and in addition allows the identification of SVs.

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 Novel Missense Mutation in Human Receptor Roundabout-1 (ROBO1) Gene Associated with Pituitary Stalk Interruption Syndrome

Pituitary stalk interruption syndrome (PSIS) is characterized by the association of an absent or thin pituitary stalk, an absent or hypoplastic anterior pituitary lobe and an ectopic posterior pituitary (EPP) lobe. The causes of this anatomical defect include both genetic and environmental factors. Molecular genetic defects have been indentified in a small number of patients with PSIS. A 4-year-old boy presented with hypoglycemia and hyponatremia associated with growth hormone, thyroid stimulating hormone, and adrenocorticotropic hormone deficiencies. The patient had right sided strabismus. magnetic resonance imaging images showed pituitary hypoplasia, EPP and absent pituitary stalk. A novel Receptor Roundabout-1 (ROBO1) missense mutation (c.1690C>T, p.Pro564Ser) that may contribute to the disorder was found in this patient and his mother, who also exhibited pituitary abnormalities.

Tumors of the Neurohypophysis: One Unit's Experience and Literature Review.

OBJECTIVE: To evaluate and understand the clinical behavior and radiologic correlates of tumors originating from the posterior pituitary gland. To review the management strategy for these rare tumors and add to the limited existing literature. METHODS: Retrospective review of 8 cases (5 pituicytomas, 2 spindle cell oncocytomas, and 1 granular cell tumor) managed at our institution between 2004 and 2019. The patients' clinical course, histologic features, and radiologic findings were reviewed. Their management and long-term follow-up is presented and compared with the literature. RESULTS: Long-term follow-up ranged from 1 to 9 years. There was 1 recurrence in a patient with spindle cell oncocytoma, and this was treated with radiotherapy. The endoscopically managed cases resulted in complete tumor excision with no recurrence. CONCLUSIONS: Epidemiologic data on primary tumors of the neurohypophysis is limited because of the rarity of these tumors. This study adds to the literature that these tumors behave as World Health Organization grade I tumors, although close follow-up is recommended as a few cases have shown recurrence. The endoscopic approach resulted in better gross total tumor resection rate in this series.

Ectopic Posterior Pituitary, Polydactyly, Midfacial Hypoplasia and Multiple Pituitary Hormone Deficiency due to a Novel Heterozygous IVS11-2A>C(c.1957-2A>C) Mutation in the GLI2 Gene

A novel heterozygous IVS11-2A>C(c.1957-2A>C) mutation in the GLI2 gene is reported. There was an extremely distinct phenotypical expression in two siblings and their father. The index case was a boy who developed cholestasis and hypoglycaemia in the neonatal period. He had bilateral postaxial polydactyly, mid-facial hypoplasia, high palatal arch, micropenis, and bilateral cryptorchidism. Laboratory examination revealed a diagnosis of multiple pituitary hormone deficiency. There was severe anterior pituitary hypoplasia, absent pituitary stalk and ectopic posterior pituitary on magnetic resonance imaging which suggested pituitary stalk interruption syndrome with no other midline structural abnormality. Molecular genetic analysis revealed a novel heterozygous splicing IVS11-2A>C(c.1957-2A>C) mutation detected in the GLI2 gene. His father and a six-year-old brother with the identical mutation also had unilateral postaxial polydactyly and mid-facial hypoplasia although there was no pituitary hormone deficiency. This novel heterozygous GLI2 mutation detected appears to present with an extremely variable clinical phenotype, even in related individuals with an identical mutation, suggesting incomplete penetrance of this GLI2 mutation.

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.

Posterior pituitary dysfunction following traumatic brain injury: review.

Neurohypophysial dysfunction is common in the first days following traumatic brain injury (TBI), manifesting as dysnatremia in approximately 1 in 4 patients. Both hyponatremia and hypernatremia can impair recovery from TBI and in the case of hypernatremia, there is a significant association with excess mortality. Hyponatremia secondary to syndrome of inappropriate antidiuretic hormone secretion (SIAD) is the commonest electrolyte disturbance following TBI. Acute adrenocorticotropic hormone (ACTH)/cortisol deficiency occurs in 10-15% of TBI patients and can present with a biochemical picture identical to SIAD. For this reason, exclusion of glucocorticoid deficiency is of particular importance in post-TBI SIAD. Cerebral salt wasting is a rare cause of hyponatremia following TBI. Hyponatremia predisposes to seizures, reduced consciousness, and prolonged hospital stay. Diabetes insipidus (DI) occurs in 20% of cases following TBI; where diminished consciousness is present, appropriate fluid replacement of renal water losses is occasionally inadequate, leading to hypernatremia. Hypernatremia is strongly predictive of mortality following TBI. Most cases of DI are transient, but persistent DI is also predictive of mortality, irrespective of plasma sodium concentration. Persistent DI may herald rising intracranial pressure due to coning. True adipsic DI is rare following TBI, but patients are vulnerable to severe hypernatremic dehydration, exacerbation of neurologic deficits and hypothalamic complications, therefore clinicians should be aware of this possible variant of DI.

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.