The malignant lymphomas seen in patients who are receiving immunosuppressant therapy after an organ transplant are in many ways similar to those seen in AIDS patients. They are usually large cell or small non-cleaved cell lymphomas but polymorphous B-cell hyperplasias and plasma cell dyscrasias also occur. These lymphomas occur with greater than expected frequency in the CNS. Transplant patients receiving immunosuppressant medications tolerate chemotherapy poorly often developing profound and prolonged pancytopenia. Their lymphoma should be treated in a stepwise fashion. 

1. The immunosuppression should be reduced to the absolute minimum possible. Some lymphomas will spontaneously regress if the immunosuppression can be sufficiently reduced.        
2. If reduction of immunosuppression fails to control the lymphoma, the chair of the Lymphoma Tumour Group should be consulted to determine if novel experimental treatment would be of use. Rituximab is effective for such patients and may be recommended (Cook, Lancet, 1998; 354:1698).