DISEASE CHARACTERISTICS: Histologically proven lymphoproliferation following organ (kidney, liver, or heart) allograft Bidimensionally measurable disease If all disease removed at biopsy, eligible only if recurrence is bidimensionally measurable Group 1 (clinically urgent disease): Histologically proven involvement of the allograft OR Histologically proven bone marrow involvement OR Liver involvement with hepatic insufficiency Bilirubin greater than upper limit of normal (ULN) OR SGOT or SGPT at least 2 times ULN OR Clinical hepatic encephalopathy OR LDH at least 3 times ULN OR Systemic sepsis OR Locally urgent lesions Tonsillar enlargement that threatens airway Superior vena cava syndrome Bilateral hydronephrosis Postobstructive pneumonia OR Small noncleaved lymphocytic lymphoma (i.e., adult Burkitt's lymphoma) Group 2: All other patients No CNS disease only