Primary tumors of the Posterior Pituitary gland: A systematic review of the literature in light of the new 2017 WHO classification of pituitary tumors.

Abstract Objective CThe rare clinical entity of primary posterior pituitary tumors (PPTs) includes pituicytomas, granular cell tumors, spine cell oncocytomas, and sellar ependymomas. The recent WHO 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 above characteristics of primary PPTs. Methods Our summary involved an in-depth review of the current literature published on PPTs. Our systematic review was carried out using PubMed database and PRISMA guidelines. Results Initial search identified 282 publications. After strict application of the inclusion criteria, we found 16 articles for ‘case series of primary PPT patients (N > 5)’ and 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, radiological, histopathological profile of primary PPTs and their treatment outcome. Conclusions Primary PPTs are a rare group of pituicyte-derived low-grade non-neuroendocrine neoplasms that arise from the sellar region. The nondescript radiographic findings and subtle endocrine abnormalities also veil their accurate diagnostic prediction. As demonstrated 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 endocrinological knowledge base.