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.

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.

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.

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.

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.

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.

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.

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.

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.

Xanthomatous hypophysitis.

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

Endonasal endoscopic pituitary adenoma resection: preservation of neurohypophyseal function.

OBJECTIVES: In the past 10 years, endoscopic resection of pituitary adenomas has become an alternative to microsurgical resection with the additional advantage of increasing the patient's postoperative comfort. This analysis explored whether endoscopic resection can reduce the risk of postoperative neurohypophyseal dysfunction. DESIGN: We rated and compared the need to administer desmopressin during the first four postoperative days and with the need after a follow-up of at least 3 months (chronic administration). SETTING: Three groups of patients were compared: Patients in group 1 were operated on microscopically. Patients in group 2 were operated on endoscopically. Patients in group 3 were operated on endoscopically with intraoperative magnetic resonance imaging (iMRI). PARTICIPANTS: Group 1 was made up of 50 patients treated in 1999; group 2 comprised 50 patients operated on from 2006 to 2007; and Group 3 comprised 50 patients operated on in 2008. MAIN OUTCOME MEASURES: In group 1 the need to use desmopressin postoperatively occurred in eight patients; three needed chronic treatment. In group 2 the need for postoperative application of desmopressin occurred in four patients; none required chronic treatment. In group 3 desmopressin had to be administered postoperatively in five patients but only temporarily. RESULTS AND CONCLUSIONS: Endoscopic surgery is a safe and effective method for the resection of pituitary adenomas. The rate of chronic desmopressin application was reduced. In conjunction with iMRI and navigation, the endoscopic technique allows increased radicality together with fewer adverse effects.

Granular cell tumor of the neurohypophysis with optic tract edema.

Granular cell tumor of the neurohypophysis is a rare disease entity. To our knowledge, this is the first report concerning a granular cell tumor of the neurohypophysis associated with optic tract edema. A 55-year-old man underwent brain magnetic resonance imaging (MRI) for a medical check-up, and a suprasellar tumor was detected. Brain computed tomography (CT) demonstrated a well delineated, homogenous, slightly hyperdense suprasellar tumor. MRI detected a lobular tumor that was isointense on T1-weighted images, hypointense on T2-weighted images, and showed homogeneous enhancement after administration of a gadopentetate dimeglumine. T2-weighted images and fluid-attenuated inversion recovery (FLAIR) images demonstrated a hyperintense region in the optic tract. Subtotal tumor resection was performed, and histological examination confirmed the diagnosis of granular cell tumor. Postoperative MRI showed that the tumor volume was reduced and optic tract edema diminished compared with the preoperative findings. We also review the literature focusing on radiographic findings, and compare the effectiveness of MRI and CT for diagnosing granular cell tumor of the neurohypophysis.

Endoscopic endonasal transsphenoidal "above and below" approach to the retroinfundibular area and interpeduncular cistern--cadaveric study and case illustrations.

OBJECTIVE: To evaluate the feasibility of reaching the interpeduncular cistern (IC) through an endoscopic endonasal approach that leaves the pituitary gland in place. METHODS: In a series of 10 injected cadaver heads, the transtuberculum ("above") and transclival ("below") approaches were combined, without pituitary transposition. Using 0-degree, 30-degree, and 45-degree endoscopes, the extent of overlap and if a blind spot occurred were determined. Also, the visualization of the IC was compared with the transposition of the pituitary gland approach. Nonparametric statistics were used to evaluate the results. The approach was implemented in 2 patients. RESULTS: For both the "above" and "below" views, there was a statistically significant increase in field of view when comparing the 0-degree endoscope with either the 30-degree endoscope (P < 0.05) or the 45-degree endoscope (P < 0.05). There was no difference between the 30-degree endoscope and the 45-degree endoscope (P > 0.05) in the "below" approach, but there was a difference (P < 0.05) in the "above" approach. There was no blind spot with any combination of endoscopes. There was no practical statistically significant difference between the transposition approach and the "above and below" approach. The "above and below" approach was used successfully in 2 surgeries. CONCLUSIONS: It is possible to work both "above" and "below" the pituitary gland to reach the IC through an endoscopic endonasal approach. The advantages are the maintenance of normal pituitary and parasellar anatomy and the minimization of the size of the skull base defect. There is no blind spot using this approach that would be revealed with a pituitary transposition. The feasibility of this approach has been confirmed in 2 patients.