CD8A and mature T-cell and NK-cell non-Hodgkin lymphoma: Accordingly, the only case of iT-LPD-GI in the workshop that showed weak staining for PD1 (LYWS-24; 1/7 cases), was a case double CD4/CD8-negative and carried a FAT1 variant, a gene alteration that has been identified in PTCL and linked with worse prognosis [66].