ABSTRACT
Introduction : The skin may be involved in inborn errors of immunity (IEI) and serve as important clues for diagnosis. We report a boy presented with subcutaneous abscesses caused by Pseudomonas aeruginosa and diagnosed as X-linked agammaglobulinemia (XLA). Case Report : A 13-months-old boy patient was referred to our immunology clinic with a history of recurrent fever and skin lesions resistant to conventional therapies on his limbs and cyclic neutropenia. He was the first child of consanguineous parents. His past medical history revealed that he had been suffering from recurrent otitis media, sinopulmonary infections, and conjunctivitis since the age of four months. He was hospitalized with a diagnosis of otitis media, and his fever persisted despite the given antibiotic treatment. Skin abscesses on his extremities occurred and were drained. On physical examination, there were a total of 16 erythematous, hemorrhagic subcutaneous nodules with central black eschar. His tonsils were rudimentary. Peripheral blood sampling showed a white blood cell count 41.3 × 109 /L with 52.3 × 109 /L neutrophils, 33.1 × 109 /L lymphocytes, %2.6 × 109 /L eosinophils, hemoglobin 9.9 g/L, and a platelet count of 397 × 109 /L. Sedimentation 18 mm/h. COVID-19 real-time PCR was negative. His immunological screening revealed that agammaglobulinemia and absence of B cells, consistent with X-linked agammaglobulinemia (Table 1). BTK gene sequence analysis showed the presence of a BTK:c.404-406delACA and BTK:c.407-408insCTTTA hemizygous mutations. To our knowledge, it has never been described before that the compound heterozygosity of these mutations causes X-linked agammaglobulinemia. These variants were classified as likely pathogenic according to the ACMG guidelines and confirmed as XLA. His mother is the carrier. Pseudomonas aeruginosa was isolated in his abscess cultures. Abscess lesions on the right and left leg were drained again, but they repeated. Hereby, the abscess lesions and subcutaneous nodules were evacuated by plastic surgery, and the daily dressing was done with silver material. In the follow-up, the skin lesions improved gradually. The patient was discharged with immunoglobulin replacement therapy and prophylactic antibiotic. Conclusion : Pseudomonas skin infection is common among IEIs, especially patients with neutropenia. XLA should be kept in mind in the evaluation of unexplained cyclic neutropenia and skin abscess resistance to therapy. (Table Presented).