RESUMO
A clinicopathological study of nine patients who developed systemic lymphadenopathy following renal transplantation and immunosuppressive therapy (OKT3 and anti-thymocyte globulin) showed a rapidity of onset and disappearance of lymphadenopathy (nine of nine cases), a frequent association of systemic signs (nine of nine cases), and a heterogeneity of histological patterns ranging from diffuse lymphoid hyperplasia to one incorrectly considered to be immunoblastic lymphoma. The coexpression of both light chains was useful in the exclusion of the diagnosis of B lymphoma. These posttransplant lymphoproliferative syndromes seem to represent an allergic reaction to the introduction of foreign protein resembling serum sickness rather than a viral infection favored by immunosuppression, although in one case (with pseudolymphomatous features) a virus was the likely mechanism.