A 9-month-old male initially presented with persistent left submandibular abscess, resistant to multiple courses of antibiotics, and required complete excision of affected tissue. No organisms were identified. At 10 months of age, the patient presented to their local emergency department and was admitted into the hospital with persistent high fevers of unknown etiology and concerns for antibiotic associated diarrhea. Shortly after admission, patient was transferred to the pediatric intensive care unit (PICU) for concerns of an acute abdomen with septic shock, in the setting of infectious colitis versus gastroenteritis. Gastrointestinal workup included an esophagogastroduodenoscopy/colonoscopy, which revealed a grossly abnormal colon in addition to small-bowel disease concerning for chronic granulomatous disease (CGD). Initial dihydrorhodamine (DHR) test demonstrated absent neutrophil oxidative bursts, suggestive for X-linked complete CGD. Genetic testing confirmed CYBB sequencing abnormalities with a mutation at c.389G.C(p.Arg130Pro). With persistent fevers, he developed a hyperinflammatory state consistent with CGD-related hemophagocytic lymphohistiocytosis (HLH) and he was treated with high-dose intravenous immunoglobulin (IVIg) and steroids. McLeod phenotype was sent and negative. The patient proceeded with a mismatched unrelated (DRB1) bone marrow transplant (BMT) after reduced-intensity conditioning. Although Day +30 chimerisms were 1.5% donor T cell and 93% donor CD33, by Day +60, he developed secondary graft failure with autologous immune reconstitution and had 0% donor chimerisms across all cell lines. A decision was made to plan for a second transplant, approximately one year after his first transplant. In preparation for a repeat BMT, DHR was sent demonstrating 30% function. Further confirmation testing was sent through the National Institutes of Health (NIH), which confirmed true neutrophil oxidative burst, and a second transplant was not needed as he developed no infectious or immune complications related to his graft-versus-host disease (GvHD). This case illustrates that in periods of neutrophil exhaustion, there may be additional loss of neutrophil function in patients with incomplete X-linked CGD. As a result, routine screening for incomplete X-linked CGD should be considered in all patients with X-linked CGD.
