Pyoderma Gangrenosum in a Patient with X-Linked Agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disorder caused by germline mutations of B-cell tyrosine kinase (BTK) gene. It is characterized by decreased serum immunoglobulins levels and circulating mature B cells. This defect in humoral immunity leads to increased susceptibility to infection. Pyoderma gangrenosum (PG) is an uncommon, ulcerating, neutrophilic dermatosis. Here we report PG in an 8-year-old patient with XLA. The patient received intravenous immunoglobulin treatment in conjunction with prednisone and topical application of 0.03% tacrolimus ointment and the ulcer was almost completely healed in the 2 weeks of follow-up. The coexistence has been rarely reported. XLA may be a possible cofactor in the pathogenesis of PG.