NCOG-34. METASTATIC PAPILLARY TUMOR OF THE PINEAL REGION: ROLE OF STEREOTACTIC IRRADIATION AND ADJUVANT TEMOZOLOMIDE

Abstract

Abstract INTRODUCTION Papillary tumor of the pineal region (PTPR) is a very rare tumor comprising < 1% of all intracranial neoplasms. It was first included as a distinct tumor entity in the 2007 World Health Organization classification. Due to its rarity, only anecdotal data is currently available to guide management. However, with these tumors being recognized more frequently, further molecular observations and therapeutic experiences are necessary. Herein, we report an unusual case of PTPR with a previously treated leptomeningeal metastasis (LM) whom we successfully managed with Gamma Knife Radiosurgery (GKRS) and adjuvant temozolomide at time of distant brain parenchymal tumor progression. CASE REPORT: A 41-year-old man presented with headache and diplopia in 2015, MRI brain revealed a large cystic enhancing lesion in the pineal region protruding into the third ventricle and causing obstructive hydrocephalus. He had a ventriculoperitoneal shunt placed and underwent partial tumor resection. He then transferred care to our institution and a gross total resection was achieved. Pathology confirmed PTPR. A repeat MRI 15 months later showed evidence of radiographic LM in the cerebellum and he underwent craniospinal proton radiation therapy. He remained stable until January 2020 when a new left temporal heterogeneously enhancing multicystic lesion was identified on surveillance MRI. He underwent subtotal resection of this intra-axial lesion. Histological features of the tumor were similar to his initial tumor. Somatic tumor mutation testing using FoundationOne®CDx did not reveal targetable molecular alterations. Following surgery, he received GKRS and six cycles of adjuvant temozolomide. At 21-month follow up, patient continues to do well. CONCLUSION To our knowledge, this is the first case to describe a metastatic brain intraparenchymal PTPR. We also describe a first case of successful therapeutic strategy for a distant recurrence of PTPR.