Post-transplantation lymphoproliferative disease (PTLD) is a complication of solid organ transplantation that is typically of B-cell origin and associated with Epstein-Barr virus (EBV). In patients receiving orthotopic liver transplantation (OLT) and treated with cyclosporin A. PTLD typically presents between 6 and 17 months post-transplantation as a systemic illness with involvement of the hepatic graft in a minority of cases. A small number of cases of biopsy-proven PTLD arising in the hepatic graft and limited to the liver and periportal structures have been previously reported. This report describes three additional cases of liver-localized PTLD and reviews similar cases in the literature. The donor/host origin of PTLD may have prognostic significance because the two cases in this report that are of donor origin had different clinical and pathologic features compared with the case of host origin. A rapid PCR-based technique for determining the origin of PTLD is described.

Differentiation between mycosis fungoides (MF) and cutaneous inflammatory processes can usually be made on clinical and histologic grounds. In difficult cases, immunohistochemical studies can be helpful since MF infiltrates usually contain a predominance of CD4+ lymphocytes, while most inflammatory lesions usually have a mixture of CD4+ and CD8+ lymphocytes. However, this determination has traditionally required the use of frozen tissue, thus severely limiting its usefulness. Recently, antibodies that differentially label CD4+ and CD8+ lymphocytes in formalin-fixed, paraffin-embedded tissue have become available (OPD4 and C8/144B respectively, DAKO (Carpinteria, CA, USA). This study tests the utility of these antibodies in the pathologic diagnosis of MF and inflammatory lesions with significant exocytosis. In 9 cases of MF for which both frozen and fixed tissues were available for comparison, the OPD4+ cell count in fixed tissue was significantly lower than the Leu-3a+ cell count in frozen tissue. Also, the C8/144B+ cell count in fixed tissue was higher than the Leu-2a+ cell count in frozen tissue, although this difference was not significant statistically. In a larger series for which only fixed tissue was available, epidermal CD4:CD8 ratios were significantly greater in 23 MF cases (mean 4.0+/-4.76) than in 35 inflammatory cases (mean 0.6+/-0.42; p = 0.001). Thus, although the studied antibodies appear to detect different epitopes in frozen versus paraffin-embedded tissue, demonstration of an elevated CD4:CD8 ratio in fixed tissue supports the diagnosis of MF, and is a helpful adjunct to routine histopathology.

Several methods have been used to evaluate engraftment after allogeneic bone marrow transplantation (BMT). We assessed the usefulness of a multiple short tandem repeat (STR) amplification kit combined with a capillary electrophoresis unit for DNA identity analysis in the evaluation of engraftment after BMT. For 17 of 18 patients, at least 1 locus showed unique alleles for the donor and the recipient. In all cases, at least 1 locus was informative for the presence of small amounts of recipient DNA. The results from STR analysis were the same as Southern blot analysis in 14 of 17 cases. Differences included mixed chimerism detected only with STR analysis, informative loci present only with STR analysis, and informative loci present only with Southern blot analysis (1 case each). By using mock mixed chimeras, minor populations of 5% were detected routinely in all loci using the kit manufacturer's default protocol. By increasing the amount of amplified DNA, minor populations of 1% were detected in all cases but not in all loci. This single reaction technique provides for faster results, reduced workforce needs, and greater sensitivity than traditional Southern blot.