Pineal Parenchymal Tumors With Intermediate Differentiation to Pineoblastoma: A Transitional Neuroectodermal Tumor of the Pineal Gland

Pineal tumors are quite rare and are fairly aggressive tumors seen in young adults and children. These tumors arise from the pineal region or recess from various types of cells in the gland and structures located in close propinquity to the gland. Pineal gland tumors have a heterogeneous spectrum that includes pineal parenchymal tumors (PPTs) and papillary tumors of the pineal region (PTPR). The PPTs are further subclassified into pineocytomas (Grade 1), PPTs of intermediate differentiation (grade 2 or 3), and pineoblastomas (grade 4) based on the World Health Organization (WHO) grades and histopathological features. We discuss the case of an 11-year-old male child who presented with complaints of headache for 15 days, vomiting for seven days, and diplopia for four days. On magnetic resonance imaging (MRI), a soft tissue density lesion was noticed in the posterior third ventricle region. Based on the location and the MRI findings, the differential diagnosis considered were a pineal lesion, a choroid plexus papilloma, or a meningioma. He underwent a right occipital ventriculoperitoneal shunt followed by total excision of the tumor, and the resected specimen was sent for histopathological examination. After pathologic examination, the diagnosis of pineoblastoma (grade 4) with features of a PPT of intermediate differentiation (grades 2-3) was revealed, and the same was confirmed on immunohistochemistry.