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

Treatment modalities and outcomes of granular cell tumors and spindle cell oncocytomas of the pituitary gland: an analysis of two national cancer databases

BACKGROUND

Spindle cell oncocytomas (SCO) and granular cell tumors (GCT) are rare primary pituitary neoplasms; the optimal treatment paradigms for these lesions are unknown and largely unexplored. Thus, using national registries, we analyze the epidemiology, management patterns, and surgical outcomes of SCOs and GCTs.

METHODS

The National Cancer Database (NCDB; years 2003-2017) and the Surveillance, Epidemiology, and End Results Program (SEER; years 2004-2018) were queried for patients with pituitary SCOs or GCTs. Incidence, extent of surgical resection, and rate of postoperative radiation use for subtotally resected lesions comprised the primary outcomes of interest. All-cause mortality was also analyzed via time-to-event Kaplan-Meier curves.

RESULTS

SCOs and GCTs have an annual incidence of 0.017 and 0.023 per 1,000,000, respectively. They comprise 0.1% of the benign pituitary tumors registered in NCDB. A total of 112,241 benign pituitary tumors were identified in NCDB during the study period, of which 83 (0.07%) were SCOs and 59 (0.05%) were GCTs. Median age at diagnosis was 55 years, 44% were females, and median maximal tumor diameter at presentation was 2.1 cm. Gross total resection was achieved in 54% patients. Ten patients (7%) had postoperative radiation. Comparing patients with GCTs versus SCOs, the former were more likely to be younger at diagnosis (48.0 vs. 59.0, respectively; p < 0.01) and female (59% vs. 34%, p = 0.01). GCTs and SCOs did not differ in terms of size at diagnoses (median maximal diameter: 1.9 cm vs. 2.2 cm, respectively; p = 0.59) or gross total resection rates (62% vs. 49%, p = 0.32). After matching SCOs and GCTs with pituitary adenomas on age, sex, and tumor size, the former were less likely to undergo gross total resection (53% vs. 72%; p = 0.03). Patients with SCOs and GCTs had a shorter overall survival when compared to patients with pituitary adenomas (p < 0.01) and a higher rate of thirty-day mortality (3.1% vs 0.0%; p = 0.013).

CONCLUSION

SCOs and GCTs are rare pituitary tumors, and their management entails particular challenges. Gross total resection is often not possible, and adjuvant radiation might be employed following subtotal resection.

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

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

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.

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.

[The 2017 WHO classification of pituitary tumors]

The 2017 WHO classification of pituitary tumors is still based on structural analyses and expression of various pituitary hormones. Three innovations have to be considered: (1) The expression of pituitary transcription factors Pit‑1, T‑Pit and SF‑1. (2) The term "atypical adenoma" was replaced by "aggressive adenoma". (3) The three tumor types of the neurohypophysis (pituicytoma, spindle cell oncocytoma, granular cell tumor) are defined by their common expression of TTF‑1. Craniophyryngiomas are identified as adamantinomatous type by focal nuclear expression of β‑catenin or as papillary type by demonstration of BRAF V600E mutation. Further primary tumors of the pituitary are extremely rare. These and also the other tumors of the sellar region can be structurally very similar to pituitary adenomas but can be-nearly without exception-differentiated by immunocytochemistry.

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.

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.