KBTBD4 and pineocytoma: In summary, genetic and epigenetic profiling identifies two broader subgroups of PPTIDs with distinct histological features and clinical course: (1) the PPTIDs with KBTBD4 insertions which have the methylation profile subtypes PPTID-A or PPTID-B and frequently have a small-cell morphology and an unfavourable clinical course and (2) the PPTIDs without KBTBD4 insertions, herein suggested to be called PPTID-C, which have a methylation profile most similar to pineocytoma and frequently show a large-cell morphology, loss of chromosome 13q, and a favourable clinical course.