OLIG2 and primary central nervous system lymphoma: Pathological findings revealed DLBCL (PT-11 and PT-19) with CD20, Bcl-6 and MUM1 positivity; germinoma (PT-31) with PLAP and c-kit positivity; glioblastoma (PT-21) with morphological changes and Olig2 positivity; B-cell lymphoma (PT-28) with PAX5 positivity; leukaemia (PT-29) with blastoid cells positive for myeloperoxidase; primary CNS lymphoma (PT-20) without malignancy but positive for CD20 and CD5 and cerebral amyloid angiopathy (PT-33) confirmed by scarlet and Congo red staining.