Pituicytoma: Review of commonalities and distinguishing features among TTF-1 positive tumors of the central nervous system

Case report: Concurrent malignant triton tumor and relapsed pituitary adenoma in the sellar region

Malignant triton tumor (MTT) is a rare kind of malignant peripheral nerve sheath tumors, histologically characterized by rhabdomyoblastic differentiation. There are limited reports of MTT occurring in the intracranial area. The treatment modality consisting of total surgical resection plus post-operative radiotherapy is generally accepted. However, even with optimal treatment, most patients will die within a few months. We report a 71-year-old man with a history of pituitary adenoma, who underwent surgical treatment and postoperative gamma knife therapy. Magnetic resonance imaging (MRI) of the brain revealed a mass with two distinctive components in the sellar area. Postoperative pathology found that the lesion consisted of a MTT and a relapsed pituitary adenoma. The present case is the first report of MTT that occurred in the sellar area. It is also the first case of intracranial MTT with other concurrent tumors (relapsed pituitary tumors). Meanwhile, this case has a clear history of radiation therapy, suggesting that the occurrence of MTT may be related to radiation.

Pituicytoma with pleomorphism: A case report with cytological findings

Pituicytoma is a rare neoplasm, arising in the posterior pituitary or in the hypophyseal stalk, and its cytological findings have not yet been well-described. We have experienced a case of pituicytoma, which was difficult to diagnose intraoperatively, because of its cellular pleomorphism. A tumor measuring 18 mm in maximum diameter was found at the sella turcica in a Japanese woman in her forties. Both intraoperative crush cytology and histology of the resected tumor showed pleomorphic spindle or round cells, including multinucleated cells. Tumor cells were positive for TTF-1, S-100 protein, and vimentin, partially positive for glial fibrillary acidic protein and epithelial membrane antigen, and negative for synaptophysin, hormones of the anterior pituitary gland, CD34, Olig2, PAX8, and napsin A. Ki-67 labeling index was 2.0%. Tumors included in the differential diagnosis in general are pituitary adenoma, craniopharyngioma, germinoma, and metastatic tumor on the radiological standpoint, and pilocytic astrocytoma and meningioma on the cytological standpoint. However, our case was difficult to differentiate especially from high-grade glioma only by morphology, and immunohistochemistry including TTF-1 was helpful.

A simplified overview of the World Health Organization classification of central nervous system tumors 2021

Background:

Building on the 2016 updated fourth edition and the work of consortium to inform molecular and practical approach to CNS tumor taxonomy, the major dramatic change occurs in 2021 fifth edition by advancing the role of molecular diagnostics in CNS tumor classification. The present review summarizes the major general changes in the 2021 fifth edition classification and the specific changes in each taxonomic category.

Methods:

The review was designed in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Articles published in PubMed Central, Medline, and Embase databases till now were all searched. Only nonexperimental and nonanimal clinical studies were included in the study. Articles written only in the English language were considered.

Results:

All IDH mutant diffuse astrocytic tumors are considered in a single type “astrocytoma IDH mutant” and then graded as CNS WHO Grades 2–4. Pediatric-type diffuse gliomas are now classified as separate entity. Anatomical site is also taken into consideration to classify ependymoma. The “Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant” and “Atypical neurofibromatous neoplasm of unknown biological potential” are new tumor type added to pineal and neurofibroma group, respectively. Mesenchymal tumor is now termed as only solitary fibrous tumor. Adamantinomatous and papillary subtype of craniopharyngioma are now classified as distinct tumor type. The new term “Pituitary neuroendocrine tumor” has been coined for pituitary adenoma.

Conclusion:

The WHO CNS-5 introduces a new knowledge into the classification with progressive manner by introducing newly recognizing entities, by obsoleting tumor type, and by adjusting the taxonomic structure.

Skull Base Tumors: Neuropathology and Clinical Implications

Tumors that arise in and around the skull base comprise a wide range of common and rare entities. Recent studies have advanced our understanding of their pathogenesis, which in some cases, have significantly influenced clinical practice. The genotype of meningiomas is strongly associated with their phenotype, including histologic subtype and tumor location, and clinical outcome. A single molecular alteration, NAB2-STAT6 fusion, has redefined the category of solitary fibrous tumors to include the previous entity hemangiopericytomas. Schwannomas, both sporadic and familial, are characterized by near ubiquitous alterations in NF2 , with additional mutations in SMARCB1 or LZTR1 in schwannomatosis. In pituitary adenohypophyseal tumors, cell lineage transcription factors such as SF-1, T-PIT, and PIT-1 are now essential for classification, providing a more rigorous taxonomy for tumors that were previously considered null cell adenomas. The pituicyte lineage transcription factor TTF-1 defines neurohypophyseal tumors, which may represent a single nosological entity with a spectrum of morphologic manifestations (ie, granular cell tumor, pituicytoma, and spindle cell oncocytoma). Likewise, the notochord cell lineage transcription factor brachyury defines chordoma, discriminating them from chondrosarcomas. The identification of nonoverlapping genetic drivers of adamantinomatous craniopharyngiomas and papillary craniopharyngiomas indicates that these are distinct tumor entities and has led to successful targeted treatment of papillary craniopharyngiomas using BRAF and/or mitogen-activated protein kinase inhibitors. Similarly, dramatic therapeutic responses have been achieved in patients with Langerhans cell histiocytosis, both with BRAF -mutant and BRAF -wildtype tumors. Familiarity with the pathology of skull base tumors, their natural history, and molecular features is essential for optimizing patient care.

[The 2021 WHO classification of tumours of the central nervous system]

Rapid technical advances in molecular biology allowed for the identification of key genetic alterations in central nervous system (CNS) tumors. Our ever-expanding knowledge of brain tumor genetics and the development of new technologies, such as DNA-methylation profiling, required an update of the 2016 fourth edition of the WHO classification of CNS tumors. Updates were regularly published by the Consortium to Inform Molecular Practical Approaches to CNS Tumor Taxonomy-Not Official WHO (c-IMPACT-NOW) until the publication of the fifth edition of the WHO classification of CNS tumors in 2021. In that edition, new types and subtypes are introduced and criteria for histo-molecular diagnostic and grading are refined, especially for diffuse gliomas. The definition of a broad category "diffuse glioma, pediatric subtype" (low or high grade) is a major improvement of the classification. Moreover, the nomenclature was simplified and aligned with that of other blue books. The 2021 edition truly advances the role of molecular diagnostics in CNS tumor classification. Methyloma profiling may become a cornerstone of CNS tumor diagnostic. The new WHO classification will lead to better management of brain tumor patients.

Two challenging cases of pituicytoma

INTRODUCTION

Pituicytoma is a rare tumor of the pituitary gland derived from neurohypophyseal pituicytes. CASE 1: A 58-year-old female presented with decreased vision; she was admitted to the neurosurgery department of Ege University after the detection of a pituitary macroadenoma. Magnetic resonance imaging (MRI) showed a 28 * 18 * 17-mm suprasellar mass, and laboratory tests revealed hypopituitarism. Hydrocortisone and L-thyroxine treatment were initiated, and the patient underwent resection through the endoscopic endonasal approach (EEA). The histopathological examination revealed a pituicytoma. The recurrence of tumor was detected during the 1-year follow-up, and the patient is awaiting surgery. CASE 2: A 70-year-old woman presented with visual changes; she had a past medical history of hypophyseal macroadenoma and pituicytoma resected through an EEA in 2012 and 2017, respectively. During follow-up, 2 years after the second surgery, MRI showed progression of the pituicytoma then measuring 38 × 23 × 22 mm; it had invaded the cavernous sinus and was causing hydrocephaly and panhypopituitarism. The patient underwent the third resection through the transcranial approach in order to minimize bleeding. After this surgery, the patient developed diabetes insipidus and underwent treatment with desmopressin. Histopathological examination revealed a pituicytoma. At 6-month follow-up, imaging showed a sellar suprasellar mass 37 × 22 × 24 mm invading the cavernous sinus, indicative of recurrence. In the postoperative period, the patient applied to the department of radiation oncology to have fractionated radiotherapy.

DISCUSSION

Pituicytomas are known to be low-grade tumors; because of their rarity, they are a real challenge. These patients should be followed up closely.

The 2021 WHO Classification of Tumors of the Central Nervous System: a summary

The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, is the sixth version of the international standard for the classification of brain and spinal cord tumors. Building on the 2016 updated fourth edition and the work of the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy, the 2021 fifth edition introduces major changes that advance the role of molecular diagnostics in CNS tumor classification. At the same time, it remains wedded to other established approaches to tumor diagnosis such as histology and immunohistochemistry. In doing so, the fifth edition establishes some different approaches to both CNS tumor nomenclature and grading and it emphasizes the importance of integrated diagnoses and layered reports. New tumor types and subtypes are introduced, some based on novel diagnostic technologies such as DNA methylome profiling. The present review summarizes the major general changes in the 2021 fifth edition classification and the specific changes in each taxonomic category. It is hoped that this summary provides an overview to facilitate more in-depth exploration of the entire fifth edition of the WHO Classification of Tumors of the Central Nervous System.

Clinical features, radiological profiles, pathological features and surgical outcomes of pituicytomas: a report of 11 cases and a pooled analysis of individual patient data

BACKGROUND

Pituicytoma is an extremely rare low-grade glial tumor that is closely related to the neurohypophysis axis. Most studies of pituicytomas include only several cases. To better understand this disease, we reviewed a series of cases of pituicytomas. The diagnosis and treatment of pituicytoma must be further elucidated.

METHODS

Eleven patients with pituicytoma admitted to Beijing Tiantan Hospital from 2012 to 2019 were selected. The clinical features, including radiological and histological examination, surgical records and prognosis were reviewed. Sixty-eight other previously published cases of pituicytoma also were used to analyze the predictive factors for the results. The Cox regression model was used for univariate and multivariate analyses.

RESULTS

Our patients included 5 males (45.5%) and 6 females (54.5%), with a mean age of 49.3 years. The tumor was located in the suprasellar region in 5 patients (45.5%), intrasellar region in 4 patients (36.4%), and intrasellar-suprasellar region in 2 patients (18.2%). All patients were misdiagnosed with other common tumors in the sellar region before the operation. During the operation, gross total resection (GTR) of the tumor was achieved in 6 patients (54.5%), and subtotal resection (STR) was achieved in 5 patients (45.5%). The mean progression-free survival (PFS) time was 29.82 months. Tumor progression after surgical resection occurred in 4 patients (36.4%). Among them, 60.0% of the patients (cases 4, 5, 7) with STR experienced progression, while 16.7% of the patients (case 2) with GTR experienced progression. Combined with the 68 cases in the literature, GTR was an independent risk factor for PFS time (P < 0.05).

CONCLUSIONS

Pituicytomas are more common in middle-aged people and the sellar region. The clinical manifestations of pituicytomas are different, but no diagnostic clinical features have been identified other than an abnormally abundant blood supply. Currently, GTR is the best approach for the treatment of pituicytomas. More patients and longer follow-up periods were needed to further elucidate the biological features of pituicytomas.

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.

Intraoperative cytology of pituicytomas

BACKGROUND

Pituicytoma is a rare tumor of the sella and suprasellar region. It is common for these tumors to be misdiagnosed radiographically as pituitary adenomas, meningiomas, and craniopharyngiomas. Histologically, pituicytomas are also known to show variable morphology. These factors often complicate intraoperative consultation, especially when tissue is limited.

METHODS

A database search (January 1990-June 2019) identified 13 surgically resected pituicytomas that were sent for intraoperative consultation. The intraoperative cytology was reviewed by two pathologists, and both squash preparations/smears and touch preparations were included.

RESULTS

The cytological features of pituicytomas were variable. The cytoplasm ranged from fibrillary to fine and wispy. The nuclei were round to ovoid with occasional tumors showing spindled morphology. Small nucleoli were seen in all tumors, and chromatin was fine to vesicular. While squash preparations were cellular and revealed cohesive groups of tumor cells, touch preparations were often paucicellular with the exception of one tumor. The cytological features of pituicytomas are compared to those of other tumors with similar radiographic appearances.

CONCLUSIONS

Our findings illustrate the range of cytological features of these rare tumors and highlight the difficulty in making a definitive intraoperative diagnosis. Pituicytomas should be considered in the differential of a sellar/suprasellar lesion with glial and meningioma-like cytological features.

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.

Surgical resection of granular cell tumor of the sellar region: three indications

PURPOSE

This case series evaluates the surgical management of granular cell tumor (GCT) of the sellar region. This rare entity presents a unique diagnostic and surgical challenge.

METHODS

Institutional neuropathology databases at Brigham and Women's Hospital and Massachusetts General Hospital were searched for cases with a tissue diagnosis of GCT, and with a location in the sellar region. Patient, treatment, tumor, and follow-up data were extracted.

RESULTS

Three patients had a diagnosis of GCT of the sellar region occurring over an 18-year period. All three patients were followed postoperatively at our multidisciplinary pituitary center (median follow-up = 30 months; range 12-30 months). Hormonal disturbances, an incidental lesion requiring diagnosis, and neurological symptoms were indications for surgery in these patients. Two patients underwent a craniotomy and one underwent endoscopic transsphenoidal surgery. All three patients were free of tumor recurrence at last follow-up. In one case tested, positive thyroid transcription factor-1 (TTF-1) immunohistochemistry was observed.

CONCLUSION

GCT is generally a benign tumor of the sellar region. Surgical resection is the standard treatment, more recently with transsphenoidal surgery when indicated. Surgical resection results in optimal outcome for patients.

Infectious Complications of Expanded Endoscopic Transsphenoidal Surgery: A Retrospective Cohort Analysis of 100 Cases

Objective  To identify perioperative factors that may predict postoperative cerebrospinal fluid (CSF) leak and meningitis following expanded endoscopic transsphenoidal surgery (EETS). Study Design  This is a retrospective study. This study was set at the Cedars-Sinai Medical Center, Los Angeles. A total of 78 patients who underwent EETS between January 2007 and November 2018 were participated. The main outcome measures were CSF leak and meningitis. Results  A total of 78 patients underwent a total of 100 EETS procedures; 17.9 and 10.3% of patients developed postoperative CSF leaks and meningitis, respectively. Out of eight, three patients with meningitis did not develop an observable CSF leak. The risk of developing meningitis in patients with a CSF leak was significantly higher than those without a leak, with an odds ratio (OR) of 11.48 (95% confidence interval, 2.33-56.47; p  = 0.004). Pituicytomas were significantly associated with meningitis compared with other pathologies. No other patient-specific factors were identified as risks for leak or meningitis, including method of skull base repair, sex, tumor volume, or body mass index, although there was a strong trend toward reduced CSF leak rates in patient with nasoseptal flaps used for skull base repair, compared with those without (9.5 vs. 25%). CSF protein was consistently elevated on the first CSF values obtained when meningitis was suspected. Conclusion  CSF leak and meningitis are common complications of expanded endonasal surgery No statistically significant risk factors for developing a postoperative leak other than the pathology of pituicytoma were identified, including method of skull base repair, although the use of a vascularized nasoseptal flap did trend toward a reduced CSF leak rate. CSF protein is the most sensitive marker for the presumptive diagnosis and timely treatment of meningitis.

Histologic, immunohistochemical, and molecular features of pituicytomas and atypical pituicytomas

Pituicytoma is a rare, poorly characterized tumor of the sellar region that is thought to be derived from neurohypophyseal pituicytes. Resection of pituicytomas is often associated with significant morbidity including diabetes insipidus and panhypopituitarism. Most of the literature on this tumor exists as small case series or case reports. Here we describe a cohort of fourteen pituicytoma resections from eleven patients. The average follow-up on these cases is 3.7 years with some patients having over 10 years of follow-up data available in the electronic medical record. Pituicytomas were frequently misdiagnosed on pre-operative imaging, and surgical resection was associated with persistent endocrine abnormalities. Histologically, the tumors showed a range of morphologies from epithelioid to spindled. All tumors were positive for TTF-1 with variable immunostaining for other markers including GFAP, EMA, S100, SSTR2A, and synaptophysin. Within this cohort are two patients with atypical pituicytomas which showed increased cellularity, pleomorphism, mitoses and elevated Ki-67 proliferation indexes when compared to non-atypical pituicytomas. Next generation sequencing performed on three tumors revealed alterations in genes involved in the MAPK pathway. Additionally, immunohistochemical staining for phosphorylated-ERK was positive in the majority of tumors. Increased awareness of the neoplastic entity and identification of targetable mutations have the potential to decrease the morbidity associated with resection of pituicytomas.

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.

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.

Sellar and suprasellar granular cell tumor of the neurohypophysis: A rare case report and review of the literature

Granular cell tumors of the neurohypophysis are rare tumors with a WHO grade of I. Symptomatic tumors are even more rare. In this case, we present a 50-year-old patient with a sellar and suprasellar granular cell tumor of the neurohypophysis, who reported headaches, blurred vision and unsteady gait. CT imaging showed a sellar and suprasellar mass approximately 2.9 cm in diameter with clear boundaries. Histologically, the tumor lacked any obvious atypia and contained densely arranged polygonal tumor cells with abundant granular eosinophilic cytoplasm. Staining for Alpha-1 AntiChymotrypsin (AACT), TTF-1 and PAS was diffusely positive, and S-100 staining was focally positive in the tumor cells. CD34, CK, EMA, GFAP and HMB45 staining were negative. The Ki-67 index was < 1%. According to these findings, the tumor was diagnosed as a symptomatic granular cell tumor of the neurohypophysis. We suggest that identifying the location of the tumor with imaging is helpful for understanding the granular cell tumor of the neurohypophysis. Prompt diagnosis and treatment are critical for patients.