[Progressive multifocal leukoencephalopathy after renal transplantation. Report of two cases].

Progressive multifocal leukoencephalopathy (PML) occurred in two patients after kidney transplantation. Two years after such a transplantation associated with immunosuppressive chemotherapy, a 54-year-old male developed polyneuropathy, diffuse alterations of the central nervous system and he died with the suspicion of hypertensive encephalopathy due to progressive renal failure. A 45-year-old female had kidney transplantation first complicated by Listeria monocytogenes meningoencephalitis. She was cured from this disease and had a satisfactory social rehabilitation for two years. Afterwards, she suffered from various neurological ailments, including epilepsy, that were attributed to combined renal failure and developing hydrocephalus. One year after the onset of these neurological symptoms, the grafted kidney was removed and chemotherapy was discontinued but she died a few weeks later. Both patients had typical PML. By electron microscopy, performed on formalin fixed brain tissue, intranuclear round particles (40-50 nm) could be recognized in the first case only. These two cases are confronted with the six published observations of PML following organ transplantation. The frequency of PML has been estimated at 1 for 5000 kidney transplantation, 1 for 2000 chronic lymphoid leukemia and 1 for 10,000 Hodgkin's disease.