Unsuspected Pneumocystis carinii pneumonia at presentation of severe primary immunodeficiency.

BACKGROUND: Pneumocystis carinii is an important pathogen in immunodeficiency but may be an unrecognised cause of respiratory compromise.
OBJECTIVES: To ascertain the incidence of P carinii pneumonia (PCP) at presentation of severe combined immunodeficiency (SCID), whether it had been diagnosed, and the effect of treatment on outcome.
SETTING: The supraregional paediatric bone marrow transplant unit for primary 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 before transfer. Eight were diagnosed by bronchoalveolar lavage and two by lung biopsy. In only one was P carinii identified in nasopharyngeal secretions. Five required ventilation for respiratory failure but all were successfully treated with co-trimoxazole and methylprednisolone with or without nebulised budesonide. Nine survived to bone marrow transplantation and four are long term survivors after bone marrow transplantation; no deaths were related to PCP.
CONCLUSIONS: PCP is a common presenting feature of SCID but is rarely recognised. Bronchoalveolar lavage or lung biopsy are needed for diagnosis. Treatment with co-trimoxazole is highly successful.