Pineocytoma and pineal parenchymal tumour of intermediate differentiation

The WHO classification of central nervous system tumours grades the pineal parenchymal tumours from pineocytoma (grade 1) through pineal parenchymal tumour of intermediate differentiation (grade 2 or 3) to pineoblastoma (grade 4); the intermediate tumour is defined molecularly by recurrent small in-frame insertions in KBTBD4 and the absence of the DROSHA deletions or DICER1 mutations of pineoblastoma (Acta Neuropathologica 2019). In the pooled analysis of 127 patients with the intermediate tumour, median age was 33 (range 4.5 to 75), the MIB-1 labelling index a median of 7 percent (range 1 to 30), and adjuvant radiotherapy was widely used with surgery (Radiotherapy and Oncology 2016).

How it differs from its parent: the brain tumours page groups all central nervous system tumours; these are adult tumours of one small midline gland, presenting with hydrocephalus and eye movement disorders, staged with spinal imaging and cerebrospinal fluid because of the risk of seeding, and diagnosed now by methylation profiling and KBTBD4 testing.

How common: under 1 percent of central nervous system tumours (Radiotherapy and Oncology 2016).

Treatment: pineocytoma by complete resection alone; the intermediate tumour by resection followed by radiotherapy, focal for grade 2 and craniospinal where the grade or spinal fluid findings warrant, with chemotherapy reserved for recurrence; the papillary tumour of the pineal region and pineoblastoma have their own pages.