We describe a case of idiopathic CD4+ T-lymphocytopenia (ICL) in a 59-year-old patient who presented with various opportunistic infections. The patient was diagnosed with disseminated Mycobacterium avium infection, cytomegalovirus colitis and retinitis, and esophageal candidiasis. He was successfully treated with anti-mycobacterial drugs, ganciclovir, and fluconazole, respectively. However, the patient was diagnosed with primary central nervous system lymphoma, and then died of a Trichosporon beigelii sepsis during the 2nd cycle of systemic chemotherapy.