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

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.

Spindle cell oncocytoma of the pituitary tumor: A rare case report and literature reviews

Introduction

Spindle cell oncocytoma (SCO) of the pituitary gland is increasingly established with improvements in histological and immunohistochemical examination. However, the diagnosis was often mistaken based on imaging studies and nonspecific clinical manifestations.

Purpose

This case is presented to provide an overview of the characteristics of the rare tumor as well as to demonstrate the difficulties in diagnosis and current treatments.

Clinical discussion

The pathogenesis of SCO remains unclear, and a possible origin was described. Further research is needed to optimize pre-operative diagnosis and surgical strategy.

Conclusion

SCO should be considered when images indicate some features. Gross total resection (GTR) after surgery seems to have better long-term tumor control, and radiotherapy may help decrease tumor progression in patients with non-GTR. Regular follow-up is advised because of the higher recurrence rate.

Approach to a case with an unusual cause of hypopituitarism

Hypopituitarism refers to insufficiency of one or more hormones of the pituitary and can be due to myriad causes. The clinical and radiological spectrum of the condition is heterogeneous, based on the age, gender, clinical setting and/or other past medical history. Hypopituitarism includes central hypocortisolism, hypothyroidism, hypogonadism and growth hormone deficiency. Both hypo- and hyperprolactinemia can be associated with hypopituitarism, with low prolactin signifying more extensive pituitary damage. Posterior pituitary insufficiency (arginine vasopressin deficiency), occurs either in isolation or with anterior pituitary hormone deficiency. Clinical symptomatology of hypopituitarism is usually non-specific and insidious in onset and progression. Overall, the most common cause of hypopituitarism is a pituitary adenoma and/or its management (surgery, radiotherapy, pharmacotherapy or a combination of these). However, it is this subset of patients which is more likely to be identified and managed timely, possibly alleviating the premature mortality associated with hypopituitarism. What is more challenging is the recognition of hypopituitarism in less common settings, which may be either due to direct involvement of the pituitary (infection, traumatic brain injury, or infiltrative causes) or indirectly as a consequence of the primary process (thalassemia, vasculotoxic snakebite, subarachnoid hemorrhage). These entities are often under-recognised, and increased awareness can help in greater recognition of the problem burden. Further, pituitary insufficiency in most of these settings is dynamic, which may progress, or rarely, show recovery of function. This renders complexity to the problem, but makes it even more imperative to suspect, screen and appropriately manage patients with less common causes of hypopituitarism.

Dabrafenib monotherapy for a recurrent BRAFV600E-mutated TTF-1-positive posterior pituitary tumor

Posterior pituitary tumors (PPT) expressing thyroid transcription factor-1 (TTF-1) are extremely rare low-grade neoplasms. The recent discovery of BRAF mutations in these tumors offers a potential alternative treatment using targeted therapies. We present the case of a 57-year-old female with recurrent BRAFV600E-mutated TTF-1-positive PPT treated with a BRAF inhibitor monotherapy (dabrafenib) leading to tumor regression. After 18 months of uninterrupted treatment, ongoing radiological tumor regression was observed and the patient remained asymptomatic without any significant adverse event. BRAF inhibitor is potentially a valuable treatment option for recurrent TTF-1-positive PPT with BRAF mutation.