NEET PG / USMLE – MCQ 54

A 2-week-old female newborn delivered at term is brought to the physician by her mother because of an increasingly severe diaper rash since birth. No congenital anomalies were noted after delivery. Physical examination shows a red and swollen umbilical remnant that has not separated. There are ulcerations of the skin but no purulent exudate in the area of the diaper. A culture of one of the ulcers grows Staphylococcus aureus. Despite antibiotic therapy, 1 month later she develops a perirectal fissure, culture of which grows Escherichia coli but a smear of which shows scarce segmented neutrophils. Laboratory studies now show:

Hemoglobin – 12.7 g/dL
Hematocrit – 38%
Mean corpuscular volume – 98 μm3
Leukocyte count – 89,790/mm3
Segmented neutrophils – 89%
Bands – 6%
Lymphocytes – 3%
Monocytes – 2%
Platelet count – 249,000/mm3

Serum
IgA – 92 mg/dL
IgG – 766 mg/dL
IgM – 101 mg/dL

A peripheral blood smear shows normochromic, normocytic erythrocytes and leukocytes with normal morphology. This patient most likely has which of the following conditions?
A. Acute myelogenous leukemia
B. AIDS
C. Chédiak-Higashi syndrome
D. Common variable immunodeficiency
E. Leukocyte adhesion deficiency

Correct answer : E. Leukocyte adhesion deficiency

Leukocyte adhesion deficiency (LAD), is a rare autosomal recessive disorder characterized by immunodeficiency resulting in recurrent infections. The classic description of LAD includes recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. Individuals with LAD suffer from bacterial infections beginning in the neonatal period. A WBC differential will reveal extremely elevated levels of neutrophils (on the order of 6-10x normal) because they are unable to leave the blood vessels. Bone marrow transplantation is the current standard of care.