[Absceso cerebral como manifestación inicial de Deficiencia especifica de anticuerpos].

Background: Specific antibody deficiency (SAD) is an inborn error of immunity, in patients older than 2 years, characterized by normal immunoglobulin levels and IgG subclasses, but with recurrent infections and decreased antibody responses to polysaccharide antigens.

Case report: A 10-year-old female, previously healthy, with no significant family history. She is known in this institution for symptoms of headache, vomiting and paresis. A CT scan of the skull was performed, where 4 brain abscesses, edema and displacement of the midline were observed, a right frontal trephine was performed and abscess drainage, antimicrobial management for infectology, blood cultures, Gram staining and cultures of negative drainage material. Assessed for allergy and immunology, for abscesses in deep focus, an approach was performed to rule out inborn error of immunity, immunoglobulins, isohemagglutinins, flow cytometry and response to normal protein antigens. Antibodies against post-vaccination polysaccharide antigens are requested, where a response to only 2 serotypes (18.1% response) is observed, with normal IgG subclasses, a diagnosis of specific antibody deficiency is integrated and management with immuno- globulin at replacement doses is started, as well as annual vaccination with 13 valent.

Conclusion: SAD has been considered a problem that can be resolved over time, especially in children, but in others it can evolve into more severe forms of humoral immunodeficiency. Decisions to treat with prophylactic antibiotics and/or gamma globulin are guided by clinical judgment, small studies, and recent consensus documents, which may evolve over time.