OTHR-15. Papillary tumor of the pineal region: case series of this rare pediatric entity

BACKGROUND: The optimal management of pediatric papillary tumors of the pineal region (PTPR) is not yet established. We report three cases, as an addition to the existing literature. PATIENT 1: A 22-month-old female presented with progressive ataxia and incoordination, found to have an enhancing solid and cystic mass centered within the pineal region, with associated obstructive hydrocephalus. Tumor biopsy revealed PTPR, prompting a subsequent subtotal resection. No adjuvant therapy was recommended. Patient has remained without evidence of disease progression for 92 months, since resection. PATIENT 2: An 8-year-old female presented with progressive headaches and new-onset generalized seizures, found to have a heterogeneously enhancing pineal lesion, with associated obstructive hydrocephalus. Following a biopsy demonstrating PTPR, patient underwent subtotal resection of the tumor. A second resection was completed 6 months later followed by focal irradiation. Targeted next-generation sequencing (NGS) demonstrated two non-targetable genomic alterations (CREBBP and MLL2). The patient remains without tumor recurrence, now 37 months, since irradiation. PATIENT 3: A 7-year-old male with Autism spectrum disorder presented with new-onset focal complex seizures. A brain MRI showed a heterogeneously enhancing lesion in the region of the pineal gland, with associated obstructive hydrocephalus. A tumor biopsy revealed PTPR, prompting a subsequent gross total resection (GTR). NGS demonstrated no reportable genomic alterations. Methylome profiling classified the tumor as PTPR, group B. Post-operative imaging with no residual tumor and he has remained without tumor progression, now eight months, since resection. CONCLUSION: PTPR are extremely rare in the pediatric setting, and were initially introduced in the WHO 2007 classification as grade II-III pineal gland tumors with distinct morphologic and immunohistochemical features. GTR is the mainstay of treatment but post-surgical management remains controversial. The clinical course is characterized by frequent local recurrence, hence, adjuvant chemotherapy and/or irradiation may be necessary upon disease progression.