[An unusual case of pneumocystis pneumonia--case report and review].

A 63 year old woman seeks medical attention for symptoms of fever, headache and increasing dyspnoea. She has a history of psoriatic-arthritis and uses 10 mg/week of methotrexate as arthritic treatment. There is also a history of severe alcohol abuse. She is in respiratory failure, with basal pulmonary crackles and increased serum inflammatory markers, a normal white-cell count but with a lowered lymphocyte count. A CT-scan reveals ground-glass lung changes. Bronchial biopsy reveals the fungus P. jiroveci which infects immunodeficient hosts. After extensive testing it was concluded that the patient's immunodeficiency was attributed to the combination of methotrexate, ethanol and psoriatic-arthritis. In this article, a case of pneumocystis pneumonia is reviewed as well as the infective mechanism of P. jiroveci and host-defence against the fungus. Additionally, symptoms and signs of the infection, diagnostic approach and treatment are reviewed. Because the combination of methotrexate and ethanol played a significant role in the immunodeficiency of the patient, their effect on the immune system is addressed.