Ecthyma gangrenosum due to Pseudomonas aeruginosa sepsis as initial manifestation of X-linked agammaglobulinemia: a case report

BACKGROUND: X-linked agammaglobulinemia (XLA, OMIM#300,300), caused by mutations in the Bruton tyrosine kinase (BTK) gene, is a rare monogenic inheritable immunodeficiency disorder. Ecthyma gangrenosum is a cutaneous lesion caused by Pseudomonas aeruginosa that typically occurs in patients with XLA and other immunodeficiencies. CASE PRESENTATION: We report the case of a 20-month-old boy who presented with fever, vomiting, diarrhea, and ecthyma gangrenosum. Blood, stool, and skin lesion culture samples were positive for P. aeruginosa. A diagnosis of XLA was established, and the c.262G > T mutation in exon 4 of BTK was identified with Sanger sequencing. Symptoms improved following treatment with antibiotics and immunoglobulin infusion. CONCLUSIONS: Primary immunodeficiency (i.e., XLA) should be suspected in male infants with P. aeruginosa sepsis, highlighting the importance of genetic and immune testing in these patients.