For these reasons, a needle biopsy of the T7 vertebral body under CT guidance was performed for a definitive diagnosis. The biopsy revealed the proliferation of medium-sized lymphoid cells infiltrating the bone marrow. Immunostaining was negative for CD3 and CD5 but positive for CD20 and Ki67. EBV-encoded RNA was negative on in situ hybridisation. Considering both the pathological findings and the MTX treatment history, the pathologist indicated the possibility of diffuse large B-cell lymphoma (DLBCL) or MTX-LPD, and no evidence of cancer metastasis was found (Figure 2). Here, MKI67 is linked to diffuse large B-cell lymphoma.