L:\usmle review 7 - Sinoe medical homepage.

there is circumoral pallor, and an erythematous rash with areas of desquamation is noted. The
myocardial damage that can follow this infection is produced in a manner similar to the damage
associated with which of the following disorders
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
(I)
Atopic allergy
Contact dermatitis
Graft-vs-host disease
Graves disease
Idiopathic thrombocytopenic purpura
Myasthenia gravis
Rheumatoid arthritis
Serum sickness
Systemic lupus erythematosus
59. The correct answer is E. This is a case of rheumatic fever, which is an immunologically
mediated sequela to Streptococcus pyogenes pharyngitis. It is a type II cytotoxic hypersensitivity,
involving antibodies that bind to cardiac tissue, activate complement, and thereby cause cell
destruction. It is therefore most similar to idiopathic thrombocytopenic purpura, which is also a
form of type II cytotoxic hypersensitivity, in this case mediated by antibodies against platelets
producing complement fixation and causing the clotting dyscrasia.
Atopic allergy (choice A) is a form of type I hypersensitivity, mediated by IgE antibodies and
basophils and mast cells.
Contact dermatitis (choice B) is a form of type IV hypersensitivity mediated by T cells and
macrophages.
Graft-vs-host disease (choice C) is a form of type IV hypersensitivity mediated by T cells and
macrophages.