Idiopathic CD4+ T lymphocytopenia disclosed by the onset of empyema thoracis

A 56-year-old man was admitted to our hospital in December 1996 due to empy ema thoracis. A laboratory examination revealed lymphocytopenia and CD4+ T lymphocytopenia (<300 cells/mu l). No evidence for a human immunodeficiency virus (HIV) infection was found. No malignant, hematological or autoimmune disease was detected. We thus diagnosed this case as being idiopathic CD4 T lymphocytopenia (ICL). During his hospital treatment, he was affected wi th cytomegaloviral retinitis and cured by therapy. His subsequent treatment went well without a recurrence of severe infection although a low CD4+ T l ymphocyte count continued after the recovery from empyema thoracis.