CASE REPORT Pneumocystis pneumonia revisited: Delayed diagnosis in an HIV infected individual with high blood and low lung CD4 T cell counts Ben Killingley*, Ronan Breen, Marc Lipman, Margaret Johnson The Royal Free Centre for HIV Medicine, Royal Free Hospital, London, United Kingdom Accepted 4 November 2005 Available online 3 January 2006 KEYWORDS Pneumocystis pneumonia; CD4 count; Bronchoalveolar lavage Summary The peripheral blood CD4 count is a useful marker of immunological status in HIV infection. However, it makes up only 1% of total body CD4 cells [Par- slow T. Lymphocytes and lymphoid tissue. In: Stites D, Terr A, Parslow D, editors. Basic and clinical immunology. Appleton and Lange; 1994. p. 22e40.] has a wide intra- and inter-individual variability [Turner BJ, Hecht FM, Ismail RB. CD4þ T- lymphocyte measures in the treatment of individuals infected with human immuno- deficiency virus type 1. A review for clinical practitioners. Arch Intern Med 1994;154:1561e73.] and CD4 cell pathology is just one of the immune defects caused by HIV [Fauci S. Multifactorial nature of human immunodeficiency virus dis- ease. Science 1993;262:1011e8.]. Thus a given value should always be interpreted within a specific clinical context. We describe an individual with Pneumocystis pneumonia (PCP) who was reviewed by HIV medical services several times before the correct diagnosis was made. On each occasion the possibility of PCP was dis- counted as he had a well-preserved blood CD4 count. Subsequent examination of his pulmonary T-lymphocyte subsets revealed marked CD4 lymphopenia. ª 2005 The British Infection Society. Published by Elsevier Ltd. All rights reserved. A 36-year-old asymptomatic Caucasian homo- sexual male was diagnosed with HIV infection in August 2003. In June 2004 he had a CD4 count of 425 cells/ml (18% of total lymphocytes) and was well. He remained treatment na € ıve and attended in January 2005 for routine follow up complaining of a sore throat. Oral thrush and an enlarged cervical lymph node were noted. His blood CD4 count was 360 cells/ml (20%). Amoxycillin and nystatin mouth wash were prescribed. Four weeks later he re-presented complaining of a 4-day history of fever, breathlessness and malaise. On * Corresponding author. c/o Dr Marc Lipman’s secretary, Department of Thoracic Medicine, Royal Free Hospital, Pond Street, Hampstead, London NW3 2QG, United Kingdom. Tel.: þ44 0207 941 1831; fax: þ44 0207 941 1830. E-mail address: bkillingley@hotmail.com (B. Killingley). 0163-4453/$30 ª 2005 The British Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinf.2005.11.004 Journal of Infection (2006) 53, e159ee160 www.elsevierhealth.com/journals/jinf