Unsuspected Pneumocystis carinii pneumonia at presentation of severe primary immunodeficiency

Background-Pneumocystis carinii is an important pathogen in immunodeficienc y but may be an unrecognised cause of respiratory compromise. Objectives-To ascertain the incidence of P carinii pneumonia (PCP) at prese ntation of severe combined deficiency (SCID), whether it had been diagnosed , and the effect of treatment on outcome. Setting-The supraregional paediatric bone marrow transplant unit for primar y immunodeficiencies at Newcastle General Hospital. Methods-Retrospective case note review of infants referred with a diagnosis of SCID from 1992 to 1998. Results-Ten of 50 infants had PCP at presentation; only one was diagnosed b efore transfer. Eight were diagnosed by bronchoalveolar lavage and two by l ung biopsy. In only one was P carinii identified in nasophapyngeal secretio ns. Five required ventilation for respiratory failure but all were successf ul treated with co-trimoxazole and methylprednisolone with or without nebul ised budesonide. Nine survived to bone narrow transplantation and four are long term survivors after bone marrow transplantation; no deaths were relat ed to PCP. Conclusions-PCP is a common presenting feature of SCID but is rarely recogn ised. Bronchoalveolar lavage or lung biopsy are needled for diagnosis. Trea tment with co-trimoxazole is highly successful.