A 39-Year-Old Man Comes to the Office Due to a Skin

question 702

Multiple Choice

A 39-year-old man comes to the office due to a skin rash on his lower extremities.  Two weeks ago, he had a sore throat and was prescribed a 10-day course of amoxicillin, which he completed.  His sore throat resolved, but he developed a nonpruritic rash on his legs 4 days ago.  The patient reports no joint pain, abdominal pain, diarrhea, or urinary symptoms.  Medical history is unremarkable, and he takes no other medications.  He smokes a pack of cigarettes a day, drinks 4-6 beers on weekends, and does not use illicit drugs.  The patient has had several sexual partners in his lifetime and uses condoms inconsistently.
Temperature is 36.7 C (98 F) , blood pressure is 110/80 mm Hg, pulse is 80/min, and respirations are 12/min.  A 0.5-cm mobile and nontender lymph node is palpable in the submandibular area.  There is no pharyngeal erythema.  Skin examination reveals a palpable and nonblanching rash, as shown in the exhibit.
Laboratory results are as follows:
Which of the following is the most likely cause of this patient's skin rash?

• A)Acute HIV infection
• B)Drug-induced vasculitis
• C)Henoch-Schönlein purpura
• D)Infectious mononucleosis
• E)Scarlet fever

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Definitions:

Measure of Central Tendency

A statistical measure that identifies a single value as representative of an entire distribution of data, such as the mean, median, or mode.

Statistic

A numerical value that summarizes or describes an aspect of a sample.

Parameter

A measurable characteristic that describes an aspect of a population in statistical analysis.