RESUMO
Pneumocistis carinii is a ubiquitous protozoan present in mammals which frequently causes pulmonary problems in immunodeficient patients, especially those infected with the Human Immunodeficiency Virus. Given its particular affinity with the lung area, it is rarely present in other tissues. It has on occasions been detected in the liver, spleen and lymphatic ganglia, external auditory canal, skin and to a lesser extent, other organs. It is extremely rare that the pathogen in question produces extra-pulmonary clinical conditions. The case presented is that of an ex-intravenous drug user diagnosed as a carrier of the HIV/C-3 virus, who presented indications of meningeal pathology and in whose cephalorachidian fluid samples were detected Pneumocistis carinii cysts.