Abstract: Objective: To discuss the clinical characteristicsof the Pneumocystis jirovecii pneumonia (PCP) in the non-HIV-infected blood disease patients,and to analyze its risk factors, treatment methods, prognosis and prevention measures.Methods: A female patient aged 18 years old was confirmed as acute myeloid leukemia (AML),and experienced dyspnea, chest congestion and hypoxaemia during the recovery period of hemogram after chemotherapy. The chest CT showed the bilateral lung diffuse ground glass density images. The patient had a dry cough and the oxygen saturation was gradually decreased to 75% 5 d after antibacteriological treatment. A repeat chest CT showed enlarged diffuse ground glass density images on both lungs. Considering about the possibility of PCP,the patient received oral trimethoprim/sulfamethoxazole(TMP/SMX) 1 g, once every 6 h, in combination with caspofungin.Results: Two days later,the symptoms of the patients were not improved. The patient was transferred to ICU and was diagnosed PCP by bronchoalveolar lavage. The patient was switched to oral TMP/SMX 2g, once every 8 h, in combination with caspofungin. Meanwhile,the patient received bi-level positive airway pressure ventilation (Bipap) for the increased work of breathing. Five days later,the symptoms of the patients were improved and the Bipap was stopped. The patient got better and discharged 5 d later. The patient continuely received oral TMP/SMX 2 g, once every 8 h for 36 d.Conclusion: Prevention of PCP should be focused, in the non-HIV-infected blood disease patients receiving chemotherapy. Diagnosis of PCP should be considered in these patients without prevention who once have suspected clinical manifestation of PCP in non-granulocytic phase. Early empirical treatment of PCP and ICU management in the non-HIV-infected blood disease patients with acute respiratory failure are the keys to reduce death and improve the prognosis of PCP.

Key words: acute leukemia, human immunodefieiency virus, haematology, Pneumocystis jirovecii pneumonia, chemotherapy