B-cell posttransplant lymphoproliferative disorder isolated to the central nervous system is Epstein-Barr virus positive and lacksp53 and Myc expression by immunohistochemistry.
Among the cases with non-Hodgkin's lymphoma (NHL), the largest category of RA-LPD, the frequency of p53 mutations in the non-MTX-NHL (47.6%) was significantly higher than that in the MTX-NHL (14.8%) (P < 0.05).
To study the molecular changes underscoring the RA-LPD, mutations of p53 and Bak gene were analyzed in RA-LPD with (MTX-LPD) or without methotrexate treatment for RA (non-MTX-LPD).
Alterations to the wild-type p53 mRNA sequence were found in nine of the 130 patients with low grade lymphoproliferative disorders screened, and this was confirmed by DNA sequencing in eight of eight samples.
From these findings and from data available in the literature the conclusion can be drawn that p53 gene mutations at codons 158 and 167 may be associated with lymphoproliferative disorders and that low- or intermediate-grade NHL, including leukemic mantle cell lymphoma, may frequently carry this genetic change.
Twenty-four separate PT-LPD lesions from the colon and mesentery of a 15-year-old male, developing 4 months after cardiac transplantation, were studied for clonality based on immunoglobulin heavy chain (IgH) gene rearrangements for the presence, clonality, and type of EBV infection and for the presence of c-myc, ras, and p53 gene alterations.
Recent data indicate that mutations and deletions of putative tumor suppressor genes, including the P53 and retinoblastoma genes, are also involved in the progression of lymphoproliferative disorders.