A 14-year-old girl is brought to the office due to a rash. Five days ago, the patient became ill with fever, sore throat, and malaise. Ibuprofen helped the fever. However, the sore throat persisted; so her father gave her amoxicillin, which was unused after a previous throat infection. The patient took the first dose of amoxicillin 3 days ago. Today, she noticed a rash over her entire body. She has no cough, abdominal pain, nausea, or vomiting. She has no other medical conditions and has taken amoxicillin previously without reaction. Temperature is 38.3 C (100.9 F), blood pressure is 110/70 mm Hg, pulse is 84/min, and respirations are 12/min. Examination shows enlarged, erythematous tonsils bilaterally with white exudates and diffuse bilateral cervical lymphadenopathy. Auscultation reveals a 1/6 systolic murmur along the left sternal border. The lungs are clear bilaterally. The abdomen is soft and nontender with mild hepatosplenomegaly. An erythematous, polymorphous, maculopapular rash is present over the entire body. Which of the following is the most likely diagnosis in this patient?

Question

A 14-year-old girl is brought to the office due to a rash.  Five days ago, the patient became ill with fever, sore throat, and malaise.  Ibuprofen helped the fever.  However, the sore throat persisted; so her father gave her amoxicillin, which was unused after a previous throat infection.  The patient took the first dose of amoxicillin 3 days ago.  Today, she noticed a rash over her entire body.  She has no cough, abdominal pain, nausea, or vomiting.  She has no other medical conditions and has taken amoxicillin previously without reaction.  Temperature is 38.3 C (100.9 F), blood pressure is 110/70 mm Hg, pulse is 84/min, and respirations are 12/min.  Examination shows enlarged, erythematous tonsils bilaterally with white exudates and diffuse bilateral cervical lymphadenopathy.  Auscultation reveals a 1/6 systolic murmur along the left sternal border.  The lungs are clear bilaterally.  The abdomen is soft and nontender with mild hepatosplenomegaly.  An erythematous, polymorphous, maculopapular rash is present over the entire body.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d6bb_eeb2_bc81_2b8d139053d6_MD0003_00 This patient with fever, malaise, exudative pharyngitis, cervical lymphadenopathy, and hepatosplenomegaly developed a polymorphous rash after taking amoxicillin. This presentation is most consistent with infectious mononucleosis, which is commonly caused by Epstein-Barr virus. The postantibiotic rash seen after administration of ampicillin or amoxicillin in patients with infectious mononucleosis typically occurs 2-10 days after antibiotic exposure and resolves within days of drug discontinuation. The mechanism for the rash is not completely understood but is believed to be a delayed-type hypersensitivity reaction due to virus-induced immune modification. It is not considered a true drug allergy, and most patients can subsequently receive the same antibiotic without reaction. postantibiotic rash (Choice A) Acute rheumatic fever is a poststreptococcal syndrome characterized by arthritis, carditis, subcutaneous nodules, erythema marginatum, and Sydenham chorea. This patient's maculopapular rash is not typical of acute rheumatic fever, and the 1/6 murmur is likely a benign flow murmur caused by fever rather than carditis. erythema marginatum (Choice B) Erythema infectiosum can present with a facial rash (ie, slapped-cheek appearance) and a reticular rash on the entire body. Exudative pharyngitis and hepatosplenomegaly are not common. reticular rash (Choice C) A true drug allergy (ie, IgE-mediated, type I hypersensitivity reaction) typically presents with urticaria, angioedema, wheezing, vomiting, and/or hypotension. Symptoms typically develop within minutes to hours of allergen exposure. This patient developed rash days into her antibiotic course; the postantibiotic rash seen in infectious mononucleosis does not represent a true allergy. (Choice E) Kawasaki disease presents with fever, rash, cervical lymphadenopathy, mucous membrane changes, extremity edema, and conjunctivitis. Patients are generally age <6. Exudative pharyngitis and splenomegaly are atypical, and antibiotic administration is not associated with rash. Kawasaki disease (Choice F) Stevens-Johnson syndrome (SJS) presents as a generalized rash typically triggered by certain medications (eg, sulfonamides, lamotrigine). Unlike this patient's maculopapular rash, the rash associated with SJS appears as red-purple macules and bullae, usually involves the mucous membranes, and is often accompanied by a positive Nikolsky sign (skin sloughing with gentle pressure). red-purple macules and bullae (Choice G) Streptococcal scarlet fever presents with fever, pharyngitis, and a sandpaper rash. However, the rash occurs in the first 1 or 2 days of infection and improves with amoxicillin; hepatosplenomegaly is uncommon. sandpaper rash Educational objective: Infectious mononucleosis is most commonly caused by the Epstein-Barr virus and presents with fever, malaise, exudative pharyngitis, cervical lymphadenopathy, and hepatosplenomegaly. A polymorphous, maculopapular rash frequently develops after administration of amoxicillin but does not represent a true drug allergy. References: Epstein-Barr virus and skin manifestations in childhood. (http://www.ncbi.nlm.nih.gov/pubmed/24073903) Incidence of rash after amoxicillin treatment in children with infectious mononucleosis. (http://www.ncbi.nlm.nih.gov/pubmed/23589810) Antibiotic-induced rash in patients with infectious mononucleosis. (http://www.ncbi.nlm.nih.gov/pubmed/27620494)

A 14-Year-Old Girl Is Brought to the Office Due to a Rash