Adult case of chronic granulomatous disease mimicking granulomatosis with polyangiitis

This article presents a patient who was initially diagnosed as having granulomatosis with polyangiitis (GPA), and was later diagnosed as having chronic granulomatous disease (CGD) in adulthood. We aimed to raise awareness of CGD, which can be confused with rheumatic diseases.We present a 33-year-old male patient with CGD with recurrent opportunistic bacterial and fungal infections who was diagnosed as having GPA, and had a history of recurrent lung infections and brain abscesses since childhood. The patient, who had cavitary lesions in the lung and mucosal lesions in the nose, was diagnosed as having GPA based on antineutrophil cytoplasmic antibody positivity. CGD was suspected in his last hospitalization after the patient underwent a nitro blue tetrazolium test. Accordingly, neutrophil oxidative function was tested using a dihydrorhodamine assay, which confirmed CGD. Molecular analysis of the patient revealed that the NCF1 gene had a GT deletion at the beginning of exon 2. Our patient was diagnosed as having late-onset CGD; he is currently well and taking antibiotic prophylaxis.As a result of the altered humoral immune response in CGD, there is unregulated inflammation and sustained antigen stimulation. This excessive inflammatory response can be confused with autoimmune diseases and cause delays in diagnosis. This case is important in the differential diagnosis of CGD in adult patients with recurrent opportunistic infections.