Spindle cell oncocytoma of adenohypophysis: Review of literature and report of another recurrent case

Benign and Malignant Tumors of the Pituitary Gland

Pituitary gland tumors represent approximately 10-15% of all brain tumors and the most common neoplasms of the sellar region. Among them, pituitary adenomas are the widespread accounting for more than 80%. Recently, the fourth edition of the World Health Organization (WHO) 2017 classified pituitary tumors focusing on histopathologic and molecular genetics features and introduced new entities like pituitary blastoma. Most of pituitary gland neoplasms occur sporadically, whereas 5% are related to familial syndromes. They present with several clinical manifestations including signs and symptoms related to excessive hormone secretion by the tumor, signs of hormone deficits by the normal pituitary gland and others commonly secondary to mass effects, and compression of nearby structures such as the optic chiasm; headache and visual disturbance are the most frequent mass effect symptoms. Some tumors, however, are detected as an incidental finding on magnetic resonance imaging (MRI) or computed tomography (CT) scans performed for some other reasons. A correct evaluation involves the assessment of hypothalamic-pituitary hormonal function and an ophthalmological examination once a pituitary lesion is encountered. Surgery, more specifically transsphenoidal approach, represents the primary treatment chosen for the majority of pituitary tumors (except for prolactinomas where medical treatment is indicated) allowing for pathologic analysis and complete or partial tumor removal. On the contrary, to date, craniotomy is rarely performed. Sometimes, due to the proximity of critical structures and to tumor's location and characteristics, a successful surgical procedure may often not be achievable due to the high risks related to the procedure itself. Therefore, the treatment of pituitary tumors commonly requires a multimodal approach, including surgery, radiosurgery, radiation therapy, and medical therapy. Aggressive pituitary tumors or carcinomas are associated with poor prognosis due to limited therapeutic options. Furthermore, they tend to recur quickly after initial surgical treatment or present metastasis, may be unresponsive to therapy, and are difficult to manage. In this chapter, we provide an overview of the most common pituitary gland tumors focusing on epidemiology, new pathological features, diagnosis, available treatment, and prognosis.

Pituitary spindle cell oncocytoma: illustrative case

BACKGROUND

Spindle cell oncocytoma (SCO) of the pituitary gland is an extremely rare nonfunctional World Health Organization grade I tumor. SCOs are often misdiagnosed as nonfunctional pituitary adenomas on the basis of preoperative imaging. They are often hypervascular and locally adherent, which increases hemorrhage risk and limits resection, leading to increased risk of recurrence. The authors report a case of SCO treated at their institution and provide a review of the current literature.

OBSERVATIONS

SCO of the pituitary gland can be a rare cause of progressively growing pituitary tumors that presents similarly to nonfunctional pituitary adenoma. Endoscopic transsphenoidal resection of the tumor by a multidisciplinary team allowed total resection despite local adherence of the tumor. Postoperatively, the patient’s visual symptoms improved with persistence of secondary adrenal insufficiency and secondary hypothyroidism.

LESSONS

Careful resection is needed due to SCO’s characteristic hypervascularity and strong adherence to minimize local structure damage. Long-term follow-up is recommended due to the tendency for recurrence.

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.

Risk factors for tumor recurrence and progression of spindle cell oncocytoma of the pituitary gland: a systematic review and pooled analysis

INTRODUCTION

Spindle cell oncocytoma (SCO) is an extremely rare sellar neoplasm. No observational studies have been reported so far to investigate the prognostic factors of this tumor entity. This systematic review aimed to elucidate the risk factors for tumor recurrence/progression of SCO.

METHODS

We searched for relevant articles in PubMed and Web of Science. Studies providing individual patient data with follow-up information of SCO cases were included. Pearson's Chi square and Fisher's exact test were used for categorical variables while t test or Mann-Whitney tests were applied for continuous variables, if applicable. We used the Cox regression model to assess the effects of suspected variables on progression-free survival (PFS).

RESULTS

A total of 38 case reports and case series comprising of 67 SCOs were included for final analyses. Recurrent/progressive tumors were noted in 38.8% of cases. Among the clinicopathological factors, only the extent of surgery was a significant risk factor for tumor recurrence/progression. SCO patients with a subtotal resection had a significantly higher risk for tumor relapse in comparison with complete removal (HR 7.51; 95% CI 1.75-32.31; p = 0.007).

CONCLUSION

Our study demonstrated the characteristic clinicopathological features of SCOs with a high recurrence/progression rate and outlined the predictor for tumor relapse. Failure to achieve gross total resection is the only risk factor for tumor recurrence/progression.

Posterior pituitary tumours: patient outcomes and determinants of disease recurrence or persistence

OBJECTIVE

Posterior pituitary tumours (PPTs) are rare neoplasms with the four recognised subtypes unified by thyroid transcription factor -1 (TTF-1) expression, according to the 2017 WHO classification. Though traditionally defined as low-grade neoplasms, a substantial proportion of them show recurrence/persistence following surgery.

METHODS

We selected patients with PPTs in our cohort of 1760 patients operated for pituitary tumours over the past 10 years (2010-2019). The clinical, radiological, hormonal, histopathological profiles and long-term outcomes of the three cases identified (two pituicytomas and one spindle cell oncocytoma, SCO) were analysed. Following a literature review, data of all published cases with documented TTF-1 positive pituicytomas and SCOs were analysed to determine the predictors of recurrence/persistence in these tumours.

RESULTS

Patients presented with compressive features or hypogonadism. Two had sellar-suprasellar masses. One had a purely suprasellar mass with a pre-operative radiological suspicion of pituicytoma. Two were operated by transsphenoidal surgery and one transcranially guided by neuronavigation. Histopathology confirmed spindle cells in a storiform arrangement and low Ki67 index. Immunohistochemistry showed positive TTF-1, S-100 expression and variable positivity for EMA, vimentin and GFAP. Re-evaluation showed recurrence/persistence in two patients. A literature review of recurrent/persistent pituicytoma (n = 17) and SCO (n = 9) cases revealed clinical clues (headache for pituicytomas, male gender for SCO), baseline tumour size (≥20.5 mm with sensitivity exceeding 80%) and longer follow-up duration as determinants of recurrence/persistence.

CONCLUSION

PPTs are rare sellar masses with quintessential TTF-1 positivity. Recurrent/persistent disease following surgery is determined by greater tumour size at baseline and duration of follow-up. This warrants intensive and long-term surveillance in these patients.

Spindle cell oncocytoma of the sella turcica with anaplastic features and rapid progression in short-term follow-up: a case report with proposal of distinctive radiologic features

We present a rare case of spindle cell oncocytoma (SCO) of the sella turcica with malignant histologic features and rapid progression. A 42-year-old woman experienced bilateral blurred vision and was preoperatively misdiagnosed as having a pituitary macroadenoma on magnetic resonance imaging. After surgery, SCO was diagnosed by the histopathologic features of interlacing fascicles of spindle tumor cells with finely granular, eosinophilic cytoplasm. Focal anaplastic changes and necrosis were present. Immunohistochemically, the tumor cells were positive for vimentin, epithelial membrane antigen, S-100, galectin-3, and thyroid transcription factor 1. Four months later, the tumor had progressed, and second surgery with adjuvant radiotherapy was performed; the patients remains under observation. In this report, we proposed distinctive radiologic features for differential diagnosis between SCO and other pituitary tumors.

A Comprehensive Study of Spindle Cell Oncocytoma of the Pituitary Gland: Series of 6 Cases and Meta-Analysis of 85 Cases

OBJECTIVE

To discuss optimal treatment strategy for spindle cell oncocytoma (SCO) of the pituitary gland.

METHODS

Institutional cases were retrospectively reviewed. A systematic literature search and subsequent quantitative synthesis were performed for further analysis. The detailed features were summarized and the tumor control rate (TCR) was calculated.

RESULTS

Eighty-five patients (6 institutional and 79 literature) were included. The annual incidence was approximately 0.01-0.03/100,000. The mean age was 56 years. Vision loss was present in 60%. Seventy-three percent showed hormonal abnormalities. On magnetic resonance imaging, tumor was avidly enhancing, and the normal gland was commonly displaced anterosuperiorly. Evidence of hypervascularity was seen in 77%. Gross total resection (GTR) was achieved in only 24% because of its hypervascular, fibrous, and adhesive nature. The mean postoperative follow-up was 3.3 years for institutional cases and 2.3 years for the integrated cohort. The TCR was significantly better after GTR (5-year TCR, 75%; P = 0.012) and marginally better after non-GTR + upfront radiotherapy (5-year TCR, 76%; P = 0.103) than after non-GTR alone (5-year TCR, 24%). The TCRs for those with low Ki-67 index (≤5%) were marginally better than those with higher Ki-67 index (5-year rate, 57% vs. 23%; P = 0.110).

CONCLUSIONS

Frequent endocrine-related symptoms, hypervascular signs, and anterosuperior displacement of the gland support preoperative diagnosis of SCO. GTR seems to have better long-term tumor control, whereas the fibrous, hypervascular, and adhesive nature of SCO makes it difficult to achieve GTR. In patients with non-GTR, radiotherapy may help decrease tumor progression.

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.

Spindle cell oncocytoma of the pituitary gland

OBJECTIVE

The authors report the diagnosis, management, and outcomes of 6 cases of spindle cell oncocytoma (SCO) in an effort to guide clinical diagnosis and management of these uncommon lesions.

METHODS

This study is a retrospective review of cases involving adult patients who underwent resection of pituitary lesions at the authors' institutions between January 2000 and October 2017. The authors identified patients with histopathological confirmation of SCO and collected clinical data, including preoperative, perioperative, and postoperative management, complications, and outcomes.

RESULTS

Six patients with SCO were identified. Clinical findings at initial presentation included visual disturbances, dizziness, and headache. All patients underwent resection. Four resections were initially performed by the transsphenoidal approach, and 2 resections were performed by craniotomy at an outside institution with subsequent transsphenoidal reoperations. Neither necrosis nor increased mitotic activity was seen in the tumor samples. All samples stained positive for S100 protein and thyroid transcription factor 1 and negative for glial fibrillary acidic protein and pituitary hormones. Five of the samples stained positive for epithelial membrane antigen. The average MIB-1 index was 8.3% (range 2-17). Postoperatively, 3 of the 6 patients received further treatment for progression of residual tumor or for recurrence, 2 have stable residual tumor, and 1 has had no recurrence after gross-total resection. Two patients developed postoperative complications of transient sixth cranial nerve palsy and diplopia. There were no other complications.

CONCLUSIONS

SCO poses both a diagnostic and therapeutic challenge. These tumors are often initially misdiagnosed as nonfunctional pituitary adenomas because of their sellar location and nonspecific symptomatology. Postoperatively, SCO must also be distinguished from other neoplasms of the posterior pituitary gland through histopathological examination. Resection of SCO can be challenging, given its highly vascular and adherent nature. Long-term follow-up is critical, as the tumor is associated with higher recurrence and progression rates compared to other benign neoplasms of the sella.

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.

Evaluation of expression of somatostatin receptor 1, 2, 3, 5 and dopamine D2 receptor in spindle cell oncocytomas of posterior pituitary

PURPOSE

Spindle cell oncocytomas (SCOs) are very rare tumors of the posterior pituitary with potential for locally aggressive behaviour. Their treatment includes surgery and possibly radiotherapy, however other options are lacking. Somatostatin receptors (SSTs) are a possible therapeutic target for somatostatin analogues and their expression has been demonstrated recently in closely related pituicytomas, but there are no data about their presence in SCOs.

METHODS

We collected five cases of SCO from four patients including one recurrent case. Immunohistochemical detection of TTF1, GFAP, CD68, SST₁, SST₂, SST₃, SST₅ and D2 dopamine receptor (D2DR) was performed. Intensity, percentage of positive cells and pattern of expression was evaluated in semiquantitative fashion. Protein expression of SST_1-5 and D2DR was further evaluated by western blot.

RESULTS

Mean patient age was 61.8 years (range 47-71 years) with male to female ratio 1:1. In one patient, samples from the original tumor and its recurrence 16 years later were assessed. TTF1 was positive in all five cases, no expression of GFAP and CD68 was seen. Immunohistochemical expression of SST₁ was noted in 1/5 cases, SST₂ in 2/5 cases, including recurrent case but not the original case. SST₃ was expressed in 3/5 tumors and D2 dopamine receptor in 4/5 cases. Western blot was successfully performed in four samples. SST₂, SST₃ and D2DR expression was identified in all the samples, including two cases originally negative for SST₂ and one case negative for SST₃ by immunohistochemistry. The number of positive cells and level of expression varied among different areas of the same tumors. No expression of SST₅ was observed. In the patient with the recurrent tumor, intensity of SST₂, SST₃ and D2DR expression varied between original tumor and its recurrence.

CONCLUSIONS

We demonstrated presence of different SST subtypes and D2DR in spindle cell oncocytomas. The most commonly expressed subtype was SST₂ and SST₃, while no expression of SST₅ was observed. Expression showed spatial heterogeneity and temporal changes as seen in the recurrent case. The biological meaning of SSTs expression in SCOs is unclear as well as whether it may be exploited in treatment of selected cases.