[Primary immunodeficiencies in seriously ill children: Report of 3 clinical cases].

Unlabelled: Primary immunodeficiency diseases (PID) are congenital disorders secondary to an impaired immune response. Infections, autoimmune disorders, atopy, and lymphoproliferative syndromes are commonly associated with this disorder.

Objective: To present and discuss 3 infants diagnosed with PID.

Clinical Cases: The cases are presented of three patients with PID diagnosed during their first admission to a Paediatric Intensive Critical Care Unit. The first patient, a 4-month-old infant affected by a severe pneumonia, and was diagnosed as a Severe Combined Immunodeficiency Disease. The second patient was an 8-month-old infant with Candida lusitaniae mesenteric adenitis, and diagnosed with a Chronic Granulomatous Disease. The last patient, a 6-month-old infant presented with ecthyma gangrenosum and X-linked agammaglobulinaemia.

Conclusion: PID should be suspected when an infectious disease does not responde to the appropriate therapy within the expected period. An update of each disease is presented.