A 30-year-old man presents to the clinic with a history of recurrent bacterial infections, including multiple episodes of pneumonia and skin abscesses, over the past 5 years. He denies any history of fungal or viral infections. Vital signs are within normal limits. Physical examination reveals healed scars from prior abscesses but no evidence of active infection. Laboratory evaluation shows normal complete blood count and normal immunoglobulin G, immunoglobulin A, and immunoglobulin M levels. A nitroblue tetrazolium test is abnormal.
A) Chronic granulomatous disease
Chronic granulomatous disease (CGD) is caused by defects in the neutrophil oxidative burst, leading to impaired killing of catalase-positive bacteria and recurrent bacterial infections and abscesses. The abnormal nitroblue tetrazolium test confirms defective neutrophil function, and normal immunoglobulin levels rule out humoral immunodeficiencies. Most individuals with CGD begin experiencing symptoms by age 2-5 years, with recurrent bacterial or fungal infections being the hallmark. These infections often affect the lungs, skin, lymph nodes, or liver, including abscesses, pneumonia, or osteomyelitis. In some cases, symptoms may not appear until later childhood, adolescence, or even adulthood, particularly in those with milder or X-linked forms of the disease.
Answer choice B: Common variable immunodeficiency, is incorrect. Common variable immunodeficiency involves low immunoglobulin levels and recurrent sinopulmonary infections, with normal neutrophil function.
Answer choice C: Leukocyte adhesion deficiency, is incorrect.Leukocyte adhesion deficiency causes recurrent infections with poor wound healing and delayed umbilical cord separation due to defective neutrophil migration, with normal oxidative burst.
Answer choice D: Severe combined immunodeficiency, is incorrect. Severe combined immunodeficiency presents with severe bacterial, viral, and fungal infections due to combined B- and T-cell defects, with low lymphocyte counts and immunoglobulins, which are not seen in this patient.
Answer choice E: X-linked agammaglobulinemia, is incorrect.X-linked agammaglobulinemia involves absent B cells and low immunoglobulins, leading to recurrent bacterial infections, but neutrophil function is normal, so the nitroblue tetrazolium test would not be abnormal.
Key Learning Point
Chronic granulomatous disease results from defective neutrophil oxidative burst, leading to recurrent infections with catalase-positive bacteria and abnormal nitroblue tetrazolium test results.
