Clinical Features of Pineal Parenchymal Tumors of Intermediate Differentiation (PPTID): A Single-Institution Series

Understanding and Managing Pineal Parenchymal Tumors of Intermediate Differentiation: An In-Depth Exploration from Pathology to Adjuvant Therapies

BACKGROUND

Pineal parenchymal cell tumors constitute a rare group of primary central nervous system neoplasms (less than 1%). Their classification, especially the intermediate subtype (PPTIDs), remains challenging.

METHODS

A literature review was conducted, navigating through anatomo-pathological, radiotherapy, and neurosurgical dimensions, aiming for a holistic understanding of these tumors.

RESULTS

PPTIDs, occupying an intermediate spectrum of malignancy, reveal diverse histological patterns, mitotic activity, and distinct methylation profiles. Surgical treatment is the gold standard, but when limited to partial removal, radiotherapy becomes crucial. While surgical approaches are standardized, due to the low prevalence of the pathology and absence of randomized prospective studies, there are no shared guidelines about radiation treatment modalities.

CONCLUSION

Surgical removal remains pivotal, demanding a personalized approach based on the tumor extension. This review underscores the considerable variability in treatment approaches and reported survival rates within the existing literature, emphasizing the need for ongoing research to better define optimal therapeutic strategies and prognostic factors for PPTIDs, aiming for further and more detailed stratification among them.

Pineal/germ cell tumors and pineal parenchymal tumors

INTRODUCTION

Pineal region tumors (PRTs) are tumors arising from the pineal gland and the paraspinal structures. These tumors are rare and heterogeneous that account for 2.8-10.1% and 0.6-3.2% of tumors in children and in all ages, respectively. Almost all types and subtypes of CNS tumors may be diagnosed in this region. These tumors come from cells of the pineal gland (pinealocytes and neuroglial cells), ectopic primordial germ cells (PGC), and cells from adjacent structures. Hence, PRTs are consisted of pineal parenchyma tumors (PPTs), germ cell tumors (GCTs), neuroepithelial tumors (NETs), other miscellaneous types of tumors, cystic tumors (epidermoid, dermoid), and pineal cyst in addition. The symptoms of PRTs correlate to the increased intracranial cranial pressure due to obstructive hydrocephalus and dorsal midbrain compression. The diagnostic imaging studies are mainly MRI of brain (with and without gadolinium) along with a sagittal view of whole spine. Serum and/or CSF AFP/β-HCG helps to identify GCTs. The treatment of PRTs is consisted of the selection of surgical biopsy/resection, handling of hydrocephalus, neoadjuvant and/or adjuvant therapy according to age, tumor location, histopathological/molecular classification, grading of tumors, staging, and threshold value of markers (for GCTs) in addition.

METHODS

In this article, we review the following focus points: 1. Background of pineal region tumors. 2. Pineal GCTs and evolution of management. 3. Molecular study for GCTs and pineal parenchymal tumors. 4. Review of surgical approaches to the pineal region. 5. Contribution of endoscopy. 6. Adjuvant therapy (chemotherapy, radiotherapy, and combination). 7.

FUTURE DIRECTION

RESULTS

In all ages, the leading three types of PRTs in western countries were PPTs (22.7-34.8%), GCTs (27.3-34.4%), and NETs (17.2-28%). In children and young adults, the leading PRTs were invariably in the order of GCTs (40-80.5%), PPTs (7.6-21.6%), NETs (2.4-37.5%). Surgical biopsy/resection of PRTs is important for precision diagnosis and therapy. Safe resection with acceptable low mortality and morbidity was achieved after 1970s because of the advancement of surgical approaches, CSF shunt and valve system, microscopic and endoscopic surgery. Following histopathological diagnosis and classification of types and subtypes of PRTs, in PPTs, through molecular profiling, four molecular groups of pineoblastoma (PB) and their oncogenic driver were identified. Hence, molecular stratified precision therapy can be achieved.

CONCLUSION

Modern endoscopic and microsurgical approaches help to achieve precise histopathological diagnosis and molecular classification of different types and subtypes of pineal region tumors for risk-stratified optimal, effective, and protective therapy. In the future, molecular analysis of biospecimen (CSF and blood) along with AI radiomics on tumor imaging integrating clinical and bioinformation may help for personalized and risk-stratified management of patients with pineal region tumors.

The Prognosis of Pineal Parenchymal Tumors: Development and Validation of a Nomogram Based on Surveillance, Epidemiology and End Results

BACKGROUND

Pineal parenchymal tumors are exceedingly rare, and optimal disease management has yet to be defined. In this study, we aimed to identify prognostic factors and establish a predictive model for the prognosis of patients with pineal parenchymal tumors.

METHODS

All patients with pineal parenchymal tumors in the Surveillance, Epidemiology and End Results database between 1975 and 2019 were reviewed. Data were summarized, and survival was modeled with Cox regression analyses. In addition, a nomogram predicting 5- and 10-year survival probability for pineal parenchymal tumors was developed and validated.

RESULTS

We found 691 pineal parenchymal and 1961 pineal region neoplasms during 1975 and 2019 resulting in an incidence of 35%. In total, 441 patients were excluded due to incomplete data. The final cohort was subdivided into groups based on tumor histology: pineocytomas, pineoblastomas, and pineal parenchymal tumors of intermediate differentiation. Multivariate Cox analysis identified age and beam radiation as prognostic factors in pineoblastomas. Age, histology, tumor size, extent of resection, radiation, and chemotherapy were selected to build a clinical nomogram. The C-index for the nomogram was 0.795 (95% confidence interval 0.738-0.852). The calibration curves of the 5- and 10-year survival rates showed good agreement between the nomogram predictions and actual observations.

CONCLUSIONS

This nomogram is a convenient and precise tool for clinicians to evaluate prognosis of pineal parenchymal tumors.

Radiation therapy for pineal parenchymal tumor of intermediate differentiation: A case series and literature review

Pineal parenchymal tumor of intermediate differentiation (PPTID) is a rare, primary tumor of the pineal gland. Due to its rarity, there is no consensus on optimal therapeutic strategies or standard characterization of the tumor's behavior. Here, we report 2 new cases of PPTID and an extensive review of the literature involving the use and extent of radiation therapy. Patient 1 is a 54-year-old male who presented with PPTID and drop metastases in the spinal cord, received cranial spinal irradiation (CSI), and experienced recurrence 3.5 years after treatment. Stereotactic body radiation therapy (SBRT) helped the patient into remission for 9 months. Patient 2 is a 32-year-old male with a local PPTID at presentation who went on to receive surgical resection followed by focused adjuvant radiation therapy to the pineal tumor bed. He then presented 6 years after treatment with extensive disseminated recurrence and died due to leptomeningeal disease (LMD) about 4 years after recurrence. The available literature on PPTID is limited and reported cases of LMD with ongoing follow-up in PPTID are scarce. Our report adds to the current known PPTID cases, contributing to the information available regarding prognosis and treatment response. Although an optimal therapeutic strategy for PPTID still cannot be determined, data from the literature suggest that utilizing radiation therapy in patients with low-risk disease and gross total resections as well as the use of upfront CSI have the potential to improve patient progression and survival outcomes.