Ependymoma of the sella turcica: a variant of pituicytoma

Synchronous Posterior and Anterior Pituitary Tumors: A Case Report of a Hypothetic Paracrine Relationship

Tumors of the posterior pituitary are a distinct group of low-grade sellar neoplasms. Furthermore, the coexistence with an anterior pituitary tumor is extremely unlikely and could not be a mere coincidence and could be a paracrine relationship. Here, we present a case of 41-year-old woman with Cushing syndrome and two pituitary masses on magnetic resonance imaging. Histologic examination shows two distinct lesions. The first consisted of a pituitary adenoma with intense adrenocorticotropic hormone immunostaining and the second lesion consisted of a proliferation of pituicytes arranged in vague fascicles or pituicytoma. After a narrative review of the literature, we found that synchronous pituitary adenoma and a thyroid transcription factor 1 (TTF-1) pituitary tumor were only reported eight times in the past. These patients included two granular cell tumors and six pituicytomas and all of them coexisted with pituitary adenomas, seven functioning and one nonfunctioning. We analyze the hypothesis of a possible paracrine relationship for this concomitance, but this exceedingly rare situation is still a matter of debate. To the best of our knowledge, our case represents the ninth case of a TTF-1 pituitary tumor coexisting with a pituitary adenoma.

Case Report: Sellar Ependymomas: A Clinic-Pathological Study and Literature Review

Ependymomas are primary glial tumors arising from cells related to the ependymal lining of the ventricular system. They are classified into at least nine different molecular subtypes according to molecular phenotype, histological morphology, and tumor location. Primary sellar ependymoma is an extremely rare malignancy of the central nervous system, with only 12 known cases reported in humans. We herein report a case of ependymoma located at the pituitary region in a 44-year-old female patient and discuss the molecular subtype, natural history, clinical presentation, radiological findings, histological features, immunohistochemical characteristics, ultrastructural examinations, treatment, and prognosis of sellar ependymoma. This case report may serve as a helpful reference for clinicians and radiologists in clinical practice.

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.

Primary papillary epithelial tumour of the sella: expanding the spectrum of TTF-1-positive sellar lesions

AIM

To describe four novel primary epithelial tumours of the sella with papillary architecture and Thyroid Transcription Factor 1 (TTF-1) expression.

METHODS

Paraffin-embedded tissue from the four cases and recurrence of patient 1 was investigated with haematoxylin-eosin, special histochemical stains, immunohistochemistry with a broad panel of antibodies and next-generation sequencing. The ultrastructure of one tumour was studied in tissue retrieved from paraffin.

RESULTS

The lesions occurred in three females aged 20, 26 and 42 years and a male aged 49 years. They presented with signs and symptoms secondary to pituitary stalk compression. Preoperative neuroimaging documented mixed solid and cystic, enhancing sellar masses with suprasellar extension. Histologically, the tumours showed thin papillae lined by a single layer of cytokeratin and TTF-1-positive cuboidal and cylindrical cells with mildly atypical nucleus. Next-generation sequencing performed in three cases did not identify any mutations. The main differential diagnosis included metastasis from lung or thyroid carcinoma, extraventricular choroid plexus papilloma and sellar ependymoma.

CONCLUSION

We suggest the descriptive term of primary papillary epithelial tumour of the sella (PPETS) for this entity and propose that it could represent the intracranial equivalent of thyroid-like low-grade nasopharyngeal papillary adenocarcinoma. The cell of origin of PPETS remains undetermined although the intense and ubiquitous expression of TTF-1 may suggest a derivation from the infundibulum or ventricular recess. Our study expands the spectrum of sellar TTF-1-positive tumour and challenges the view that they all derive from pituicytes.

Found at Old Age and Continuously Growing WHO Grade II Fourth Ventricle Ependymoma: A Case Report

A 74-year-old woman presented with a month-long nausea and vomiting, then she could not take a meal. She had found an asymptomatic 4th ventricular mass 6 year ago as a preoperative work-up for ovarian cancer. And during the yearly follow-up, the mass had grown continuously over 6 years, and caused symptoms in the seventh year. MRI revealed a large ovoid extra-axial mass in the fourth ventricle compressing adjacent medulla and cerebellum. Surgery achieved near total resection since the tumor tightly adhered to the brain stem of 4th ventricle floor. The histological diagnosis was ependymoma (WHO grade II). She transferred rehabilitation facility for mild gait disturbance, hoarseness and swallowing difficulty. Fourth ventricle ependymoma in the elderly is extremely rare and the growth rate has not been reported. Here, we present a rare care of 4th ventricle ependymoma found asymptomatic at elderly but continuously grow to cause local pressure symptoms.

Primary tumors of the posterior pituitary: A systematic review

In 2017, the World Health Organization established that pituicytoma, granular cell tumor (GCT), spindle cell oncocytoma (SCO) and sellar ependymomas (SE) are posterior pituitary tumors (PPT). They probably arise from the pituicytes and may constitute a unique histopathological entity. We carried out a systematic review using PubMed's database. A total of 266 patients with pathological diagnosis of PPT (135 pituicytomas, 69 GCT, 47 SCO, 8 SE and 7 mixed histology tumors) were analyzed. Gender distribution was identical and median age at diagnosis was 48 ± 21.8 years. Main presentation symptoms were visual disorders (n = 142; 58.1%), headache (n = 99; 40.5%), hypopituitarism (n = 84; 34.4%), hypercortisolism (n = 10; 4.1%), polyuriapolydipsia (n = 6; 2.4%) and acromegaly features (n = 5; 2.0%). On MRI, 122 (47.6%) patients showed sellar with suprasellar extension masses, 67 (23.1%) were suprasellar and 63 (24.6%) exclusively sellar. Median tumor size was 22.0 ± 14.2 mm. Two hundred sixty four patients underwent surgery, transphenoidal access was selected in 132 (64.4%) and craniotomy in 58 (28.3%). Complications were hypopituitarism (n = 70; 42.1%), diabetes insipidus (n = 55; 33.1%) and hemorrhage (n = 50; 30.1%). Tumor persisted in 93 patients (45.6%) and recurred in 13 (6.4%). Regarding comparison between main types of PPT, SCO patients were diagnosed later (60.0 vs 47.0 vs 47.0 years, p = 0.023), the tumor was larger 25.0 mm [10.8] vs 20.0 mm [14.2] vs 2.0 mm [15.0] and they were frequently sellar with suprasellar extension tumors (71.7% vs 46.2% vs 32.8%, p = 0.003) compared to pituicytoma and GCT. In conclusion, PPT are rare tumors and have been misdiagnosed mainly as non-functioning pituitary adenomas. Different types of PPT share similar epidemiology, clinical manifestations and surgical outcomes. Surgery is the only curative option but complications and subtotal resection are common.

Clinical features, diagnosis and therapy of pituicytoma: an update

BACKGROUND

Pituicytomas (PTs) are extremely rare, low-grade glial tumors closely related to the neurohypophyseal axis. Definite conclusions concerning the optimal diagnostic and therapeutic approach to these neoplasms are lacking to date, as most of this information has been presented as case reports.

METHODS

Retrospective review of case reports published in the scientific literature to date, including a new illustrative example treated in our department.

RESULTS

116 cases were collected. PTs had a higher prevalence in the fifth and sixth decades of life, with a slight male predominance. Main symptoms, which tended to be progressive, included visual field defects and pituitary-hypothalamic dysfunction. Radiologically, PTs were found anywhere along the hypothalamic-pituitary axis mimicking other, more frequent tumors growing in this anatomical region. Surgical treatment included both transcranial or transsphenoidal approaches, and resulted in gross total resection and morbidity rates of 46.8 and 59%, respectively; the latter essentially consisted in anterior and posterior pituitary dysfunction, with limited impact on daily quality of life.

CONCLUSIONS

Due to both low frequency and the absence of pathognomonic clinical and/or radiological features, formulating a suspicion diagnosis of PT represents a considerable challenge even for experienced professionals. The indication for treatment should be made on an individual basis, but it is inescapable in the presence of a visual field defect. The surgical approach has to be tailored according to the topography of the tumor and preoperative symptoms; the greatest challenges in accomplishing a gross total removal are represented by the degree of adherence and vascularization of the PT.

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.

What's new in pituitary pathology?

The increasing recognition of pituitary disorders and their impact on quality of life and longevity has made understanding of this small gland a subject of paramount importance. Pituitary pathology has seen many significant studies that indicate progress in identification and classification of pituitary lesions, as well as improved management strategies for patients. In this review, we outline six major areas of advances: (i) changes in terminology from 'adenoma' to 'pituitary neuroendocrine tumour'; (ii) reclassification of hormone-negative tumours based on transcription factor expression that defines lineage; (iii) updates in new pathogenetic mechanisms, including those that underlie rare lesions such as X-LAG and pituitary blastoma; (iv) clarification of hypophysitis due to immunotherapy, xanthomatous hypophysitis due to rupture of a Rathke's cleft cyst and IgG4 disease as the cause of inflammatory pseudotumour; (v) the consolidation of pituicytoma variants, including spindle cell oncocytoma and granular cell tumour based on thyroid transcription factor-1 (TTF-1) reactivity; and (vi) the pathogenetic mechanisms that distinguish papillary from adamantinomatous craniopharyngioma. The remaining challenge is clarification of the pathogenetic mechanisms underlying the development of many of these disorders.

Welcoming the new WHO classification of pituitary tumors 2017: revolution in TTF-1-positive posterior pituitary tumors

The fourth edition of the World Health Organization classification of endocrine tumors (EN-WHO2017) was released in 2017. In this new edition, changes in the classification of non-neuroendocrine tumors are proposed particularly in tumors arising in the posterior pituitary. These tumors are a distinct group of low-grade neoplasms of the sellar region that express thyroid transcription factor-1, and include pituicytoma, granular cell tumor of the sellar region, spindle cell oncocytoma, and sellar ependymoma. This short review focuses on the classification of posterior pituitary tumors newly proposed in EN-WHO2017, and controversies in their pathological differential diagnosis are discussed based on recent cases.

Pituitary Ependymoma: A Case Report and Review of the Literature

BACKGROUND

Pituitary ependymoma is exceptionally rare. Its etiology, clinical presentation, radiologic feature, and treatment strategy are still a matter of debate. Only 7 human cases with limited data were reported in the English literature, and now we described another case of pituitary ependymoma. We also systematically reviewed previously reported cases and described its potential etiology, clinical presentation, radiologic features, pathology, immunohistochemical analysis, and ultrastructural examinations.

CASE DESCRIPTION

A lesion in pituitary fossa was discovered in a 40-year-old man after suffering a progressive deterioration of vision in his right eye for >1 year with intermittent headache. The lesion was microsurgically resected and proved to be ependymoma upon pathologic and histologic examination. The patient made a fully recovery after surgery.

CONCLUSIONS

To our knowledge, only 7 patients with ependymoma in the sellar region have been described in the English literature. We reported 1 more case of pituitary ependymoma and discussed the potential etiology, clinical presentation, radiologic features, pathology, immunohistochemical analysis, ultrastructural examinations, treatment, surgery, radiotherapy, chemotherapy, and prognosis of pituitary ependymoma. The case report may serve as a helpful reference for clinicians and radiologists.

Pituitary Ependymoma, 10-Year Follow-Up after Partial Resection and Radiation Therapy

Ependymoma usually arises within the ventricles and central canal of the spinal cord. These tumors, found in the sellar region, are extremely rare. We report a case of pituitary ependymoma followed up over 10 years. A 59-year-old male patient presented with fatigue, general weakness, erectile dysfunction, and loss of body hair, including pubic hair. Brain magnetic resonance imaging (MRI) revealed a 3.3×3.5×2.3-cm sellar and suprasellar snowman-shaped enhancing mass. The tumor was partially resected via the trans-sphenoidal approach followed by postoperative radiation therapy. The pathologic confirmation was pituitary ependymoma. At the 10-year follow up, MRI revealed no evidence of tumor progression. With lack of knowledge about pituitary ependymoma, our case is the only case in which the disease has been well controlled over a long period of time without tumor progression.

Immunoprofiling of glial tumours of the neurohypophysis suggests a common pituicytic origin of neoplastic cells

PURPOSE

To analyse the antigen expression profiles of 27 cases of pituicytoma, spindle cell oncocytoma, and granular cell tumour of the sellar region concerning a common pituicytic origin of neoplastic cells.

METHODS

Material from 12 female and 15 male patients (13 granular cell tumours of the sellar region, 10 pituicytomas, four spindle cell oncocytomas) collected in the German Registry of Pituitary Tumours between 1993 and 2015 was re-evaluated according to the current WHO classification of tumours of the central nervous system and supplementary immunohistochemistry including S100-protein, CD56, CD68, thyroid transcription factor-1 (TTF-1), and Ki-67 was performed.

RESULTS

S100-protein was detected in all 27 tumours and TTF-1 in all 16 tumours that were assessed. Vimentin was expressed in all 13 cases investigated whereas broad spectrum cytokeratin was not detected in any of 14 evaluated cases. GFAP was observed in nine out of 21 cases. 15 out of 17 investigated lesions showed some CD68 expression and five out of 14 cases were labelled with CD56 antibodies. Proliferative activity did not differ significantly between the three tumour subgroups although one primary and one recurrent pituicytoma showed exceptionally high Ki-67-proliferation indices of 15.3 and 12.7 %, respectively (means: granular cell tumour of the sellar region 2.0 %, pituicytoma 2.8 %, spindle cell oncocytoma 2.7 %).

CONCLUSIONS

The study confirms and expands earlier data and is in line with the notion that the three tumour types are variants of pituicytoma.

The clinicopathological features of pituicytoma and the differential diagnosis of sellar glioma

Pituicytoma is rare and difficult to diagnose. This study explored the clinicopathological features, immunophenotype and differential diagnosis of pituicytoma. We compared 11 cases of pituicytoma and 26 cases of sellar glioma (16 pilocytic astrocytomas, four diffuse astrocytomas, three pilomyxoid astrocytomas, and three third ventricle chordoid gliomas). The 11 pituicytoma cases involved six men and five women (age: 33-65 years). Three of the 11 patients experienced recurrence due to a residual tumor, and one patient underwent three surgeries during a 6-month period. Imaging findings revealed tumors were in the intrasellar region (four cases), suprasellar region (four cases) and intra-suprasellar regions (three cases). The tumor diameters were 1.3-3.8 cm, and the preoperative diagnoses were pituitary adenoma, craniopharyngioma and meningioma. The tumors were solid and contained spindle or slightly chubby cells that were densely arranged with visible cleft-like or expanded sinusoid structures. The cells had vague boundaries, circular nuclei, fine chromatin, and a small nucleolus. Immunohistochemical staining of the pituicytomas revealed positive expression of thyroid transcription factor-1 (TTF-1) and S-100 protein (S-100), positive focal expression of glial GFAP;(five of 11 cases), and negative oligodendrocyte transcription factor 2 (Olig2), CD34 and neurofilament expression. The Ki67 index was 6% in one case and 1-2% in the other cases. Unlike pituicytoma, most sellar glioma cases exhibited GFAP and Olig2 expression, and negative TTF-1 expression. Third ventricle chordoid gliomas expressed TTF-1, GFAP and CD34, and were negative for Olig2. Our results indicate that pituicytoma typically involves dense arrangements of spindle or slightly chubby cells. The morphology is occasionally atypical, with ependymoma-like or meningioma-like structures, and occasionally exhibits pilomyxoid degeneration. Abundant sinusoids are characteristic of hemorrhagic tumors. The dense spindle cell arrangement is a relatively specific morphology, and staining for GFAP, TTF-1, Olig2 and CD4 may help differentiate pituicytoma from sellar glioma.

Suprasellar chordoid neoplasm with expression of thyroid transcription factor 1: evidence that chordoid glioma of the third ventricle and pituicytoma may form part of a spectrum of lineage-related tumors of the basal forebrain

Chordoid glioma of the third ventricle is a rare neuroepithelial tumor characterized by a unique histomorphology and exclusive association with the suprasellar/third ventricular compartment. Variously interpreted as either astrocytic- or ependymal-like, and speculatively ascribed to the lamina terminalis/subcommissural organ, its histogenesis remains, nevertheless, unsettled. Here, we report on a suprasellar chordoid glioma occurring in a 52-year-old man. Although displaying otherwise typical morphological features, the tumor was notable for expression of thyroid transcription factor 1, a marker of tumors of pituicytic origin in the context of the sellar region. We furthermore found overlapping immunoprofiles of this example of chordoid glioma and pituicytic tumors (pituicytoma and spindle cell oncocytoma), respectively. Specifically, phosphorylated ribosomal protein S6, a marker of mTOR pathway activation, was expressed in both groups. Based on these findings, we suggest that chordoid glioma and pituicytic tumors may form part of a spectrum of lineage-related neoplasms of the basal forebrain.

Surgical management of pituicytomas: case series and comprehensive literature review

OBJECTIVE

Pituicytomas are rare neoplasms that typically present as solid, noninfiltrative tumors occupying the sella and/or suprasellar space for which there is no consensus on optimal surgical management. We aimed to define a preferred surgical strategy for these tumors based on our clinical experience and comprehensive review of the world literature.

DESIGN

Case series and review of the literature.

METHODS

We documented the clinical, radiographic, and surgical findings of three patients with pituicytoma treated at our institution, as well as complications and long-term outcomes. A comprehensive review of the medical literature identified all cases of pituicytoma for which data regarding surgical approach, outcome and complications could be extracted. We compared our results with published data.

RESULTS

All three cases at our institution achieved gross total removal. Two patients underwent an expanded endoscopic endonasal transsphenoidal and transplanum (EETS-TP) approach, while one tumor was removed via craniotomy. Post-operatively all patients developed pan-hypopitutarism. The patient undergoing craniotomy suffered profound visual loss but no other neurological complications were noted. A literature review identified 67 reported cases of pituicytoma. Surgical data was available in 60 cases. Surgical approach was documented in 57 patients. Sixty-three surgeries were performed in which approach and extent of resection was available. Gross total removal was obtained in 33 % of craniotomies, 42 % of transsphenoidal procedures, and 100 % of expanded transsphenoidal procedures. Neurological complications including visual loss, hemiparesis and cranial nerve palsies were reported after craniotomy, but not after transsphenoidal approaches. Overall EETS-TP approaches were associated with the highest rate of gross total removal and no visual or neurological complications.

CONCLUSIONS

EETS-TP surgery is the preferred strategy for surgical removal of pituicytoma. EETS-TP and transsphenoidal approaches are associated with higher rates of gross total removal and lower rates of neurological complications than craniotomy. Gross total removal should be the intended goal of surgery.

Update on hypophysitis and TTF-1 expressing sellar region masses

This article reviews recent literature on sellar region masses that most closely mimic nonsecretory pituitary adenomas: hypophysitis, pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis. Even today, these four entities often cannot be confidently distinguished from each other clinically or by preoperative neuroimaging features. Thus, they often come to biopsy/surgical resection and require tissue confirmation of diagnosis. Causes of secondary and primary hypophysitis will be discussed, including two newly described types, IgG4 plasma cell hypophysitis and hypophysitis caused by anti-cytotoxic T-lymphocyte antigen 4 antibody therapy for cancer. For the neoplastic conditions, emphasis will be placed on literature that has emerged since these entities were first codified in the 2007 World Health Organization fascicle. The finding that immunohistochemical staining for thyroid transcription factor-1 is shared by pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis suggests common lineage and explains why histological overlap can be encountered. We incorporate our own experiences over the last 30 years from two referral institutions with specialty practices in pituitary region masses.

Spindle cell oncocytoma of the pituitary gland with follicle-like component: organotypic differentiation to support its origin from folliculo-stellate cells

Spindle cell oncocytoma (SCO) is a rare, non-adenomatous tumor originating from the anterior pituitary gland. Composed of fusiform, mitochondrion-rich cells sharing several immunophenotypic and ultrastructural properties with folliculo-stellate cells (FSC), SCO has been proposed to represent a neoplastic counterpart of the latter. To date, however, SCO has failed to meet one criterion commonly used in histological-based taxonomy and diagnostics; that of recapitulating any of FSCs' morphologically defined developmental or physiological states. We describe a unique example of SCO wherein a conventional fascicular texture was seen coexisting with and organically merging into follicle-like arrangements. The sellar tumor of 2.7 × 2.6 × 2.5 cm was transphenoidally resected from a 55-year old female. Preoperative magnetic resonance imaging indicated an isointense, contrast enhancing mass with suprasellar extension. Histology showed multiple rudimentary to well-formed, follicle-like cavities on a classical spindle cell background; while all the participating cells exhibited an SCO immunophenotype, including positivity for S100 protein, vimentin, EMA, Bcl-2, and TTF-1, as well as staining with the antimitochondrial antibody 113-1. Conversely no expression of GFAP, follicular-epithelial cytokeratin, carcinoembryonic antigen, or anterior pituitary hormones was detected. Ultrastructurally, tumor cells facing follicular lumina displayed organelles of epithelial specialization, in particular surface microvilli and apical tight junctions. This constellation is felt to be reminiscent of FSCs' metaplastic transition to follicular epithelium, as observed during embryonic development and physiological renewal of the hormone-secreting parenchyma. Such finding is apt to being read as a supporting argument for SCO's descent from the FSC lineage.

Pituicytoma: case report and literature review

Pituicytoma is a rare primary tumour of the neurohypophysis or infundibulum, which masquerades as a pituitary adenoma. We present a pituicytoma case in a 45-year-old female presenting as a focal lesion of the neurohypophysis. This case report reviews the clinical, neuroimaging and histopathological features of this rare tumour in order to understand it better.

Clinical features of nonpituitary sellar lesions in a large surgical series

CONTEXT

Pituitary adenomas are the most common lesions in the sellar region, but other pathologies need to be considered in the differential diagnosis.

OBJECTIVE

To assess the prevalence of unusual sellar masses in a large series of patients and identify clinicopathological factors that may aid the pre-operative diagnosis.

DESIGN

Retrospective case series.

PATIENTS

We analysed the records of 1469 transsphenoidal procedures performed between 1998 and 2009. One hundred sixteen cases (7·9%) were not pituitary adenomas.

MEASUREMENTS

Final pathological diagnosis.

RESULTS

One hundred sixteen patients (45 men, 71 women; mean age (±SD): 45 ± 17 years) with nonadenomatous lesions were divided into four major aetiological groups: cystic lesions (CYS) (53%); benign neoplasms (BEN) (22%); malignancies (MAL) (16%) and inflammatory lesions (INF) (9%). Rathke's cysts, the most common lesions, represented 42% of all cases. Twenty-five per cent of malignant lesions were metastases, and some of the MAL (e.g., fibrosarcoma, lung metastasis) had a radiographical appearance suggestive of a pituitary adenoma. The most common presenting symptoms were visual field impairment (51%) and headache (34%). Pre-operative pituitary dysfunction was present in 58% of cases, with hyperprolactinaemia (35%), hypogonadism (23%) and hypocortisolism (23%) found most frequently. Postoperative resolution of headache and visual symptoms occurred in 63% and 65% of patients, respectively. Hyperprolactinaemia resolved in 77% of cases.

CONCLUSIONS

A substantial minority of sellar masses are not pituitary adenomas. While they frequently present with the symptoms, hormone abnormalities and radiographical appearance typical of pituitary tumours, the possibility of a nonadenomatous lesion needs to be considered in the differential diagnosis.

Thyroid transcription factor 1 expression in sellar tumors: a histogenetic marker?

Pituicytomas are rare low-grade gliomas of the neurohypophysis. Their morphology and variable immunophenotype have led to speculation that they arise from pituicytes. Given the role of thyroid transcription factor 1 (TTF-1) in the developing rodent infundibulum and its expression in the adult rat neurohypophysis, we speculated that TTF-1 would be a marker of human pituicytes. Using immunohistochemistry, we found that TTF-1 is strongly expressed in fetal and adult human pituicytes. A survey of sellar masses demonstrated specific TTF-1 expression in pituicytomas (n = 3), atypical pituicytomas (n = 2), and granular cell tumors (n = 4), indicating a common pituicyte lineage. TTF-1 expression in spindle cell oncocytomas (n = 8) is less easily explained but invites speculation. Our observations may have implications for the classification of these rare sellar neoplasms, all the while acknowledging the morphological diversity of pituicyte-related neoplasms.