X-linked chronic granulomatous disease (CGD) caused by an intra-exonic splice mutation (CYBB exon 3, c.262G->A) is mimicking juvenile sarcoidosis.

BACKGROUND Chronic granulomatous disease (CGD) is caused by mutations in genes encoding nicotinamide dinucleotide phosphate (NADPH) oxidase subunits. CASE REPORT A boy was diagnosed as having juvenile sarcoidosis because he presented with cervical and pulmonary lymphadenopathy with epitheloid cells and granuloma formation and high angiotensin converting enzyme. Later, a liver abscess was diagnosed. CGD was established by a dihydrorhodamine 123 (DHR) assay and genetic analysis revealed an unusual intra-exonic splice mutation in the CYBB gene encoding gp91-phox. It did not change the amino acid sequence and allowed for residual NADPH oxidase activity explaining the late onset of the disease. CONCLUSION CGD is an important differential diagnosis of juvenile sarcoidosis.