q16 - rasuccess

[ArchivalUser]

A 4-year-old boy is seen by his pediatrician for epistaxis. The patient has a
history of multiple bacterial and viral respiratory tract infections and
eczema. An uncle had similar problems. Physical examination is
remarkable for multiple petechial lesions on the skin and mucous
membranes. Serum IgE is increased, and platelets are decreased. Which of
the following is the most likely diagnosis?
A. Acquired hypogammaglobulinemia
B. Ataxia telangiectasia
C. DiGeorge syndrome
D. Selective IgA deficiency
E. Wiskott-Aldrich syndrome

[ArchivalUser]

E. Wiskott-Aldrich syndrome

[ArchivalUser]

The correct answer is E. Wiskott-Aldrich syndrome is an X-linked
condition characterized by eczema, thrombocytopenia, and repeated
infections. Affected children may present with bleeding and often succumb
to complications of bleeding, infection, or lymphoreticular malignancy. The
platelets are small, have a shortened half-life, and appear to be deficient in
surface sialophorin (CD43). Splenectomy can correct the
thrombocytopenia, but not the immune defect. Serum IgM is usually
decreased, while IgE is frequently increased. Mutations in the Wiskott-
Aldrich serum protein (WASP) gene on the short arm of the X chromosome
are responsible for this disease.
Acquired hypogammaglobulinemia (choice A) is a disease of adults
characterized by normal numbers of B cells but low immunoglobulin
production.
Ataxia telangiectasia (choice B) is an autosomal recessive disease
characterized by progressive cerebellar dysfunction, telangiectasias, and a
variable immunodeficiency.
DiGeorge syndrome (choice C) is a developmental malformation leading
to thymic aplasia and, sometimes, hypoparathyroidism.
Selective IgA deficiency (choice D) is a relatively common condition
characterized by low levels of IgA.