A 4-year-old boy is brought to the emergency department for evaluation of persistent fevers. About 6 weeks ago, the patient developed rhinorrhea, cough, and body aches after returning from a family trip to Costa Rica. Although the other symptoms resolved, he still has intermittent fevers and aches. The fevers tend to spike in the evenings and are accompanied by a pink, nonpruritic rash. Both features completely resolve by morning. The patient has continued to attend preschool because he feels well during the day. However, he has had a fever and rash every evening for the last 5 days. The patient takes no medications. Temperature is 39.1 C (102.4 F). He appears tired. The oropharynx and bilateral tympanic membranes are normal. Cardiac examination shows tachycardia without murmurs. There are several pink macules at the waist and bilateral axillae. The spleen is palpable 3 cm below the costal margin. There is swelling of both knees and tenderness with deep palpation. Laboratory results are as follows: Which of the following is the most likely diagnosis in this patient?

Question

A 4-year-old boy is brought to the emergency department for evaluation of persistent fevers.  About 6 weeks ago, the patient developed rhinorrhea, cough, and body aches after returning from a family trip to Costa Rica.  Although the other symptoms resolved, he still has intermittent fevers and aches.  The fevers tend to spike in the evenings and are accompanied by a pink, nonpruritic rash.  Both features completely resolve by morning.  The patient has continued to attend preschool because he feels well during the day.  However, he has had a fever and rash every evening for the last 5 days.  The patient takes no medications.  Temperature is 39.1 C (102.4 F).  He appears tired.  The oropharynx and bilateral tympanic membranes are normal.  Cardiac examination shows tachycardia without murmurs.  There are several pink macules at the waist and bilateral axillae.  The spleen is palpable 3 cm below the costal margin.  There is swelling of both knees and tenderness with deep palpation.  Laboratory results are as follows:  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d73c_b74e_bc81_59dd673a8c90_MD0003_00 Juvenile idiopathic arthritis (JIA) is a chronic autoinflammatory disorder of childhood subdivided into systemic, polyarticular, and oligoarticular JIA. This patient most likely has systemic JIA, the least common subtype with a varying number of affected joints. Systemic JIA can present any time during childhood and is characterized by: Arthritis in ≥1 joint for ≥6 weeks: Commonly affected joints include the hips, knees, and hands. Patients may have arthralgias (as in this patient) prior to the onset of arthritis. Fever for ≥2 weeks: Fever occurs in a quotidian pattern in which high temperatures spike once daily (often in the evening) followed by spontaneous return to normothermia. An evanescent pink rash often accompanies the fever, as seen in this patient. Hepatosplenomegaly and lymphadenopathy are also common. Supportive laboratory findings reflect inflammation, including leukocytosis, elevated inflammatory markers, thrombocytosis, and hyperferritinemia. Anemia due to chronic inflammation and iron deficiency is also seen. Rheumatoid factor and antinuclear antibodies are typically negative in systemic JIA. In the setting of classic symptoms (quotidian fever, evanescent rash, arthritis) of <6 weeks duration, a tentative diagnosis of probable systemic JIA may be made. (Choice A) Acute rheumatic fever can present with fever, rash, and migratory arthritis after untreated group A streptococcal pharyngitis. However, fever is typically persistent rather than quotidian. In addition, the classic rash has an expanding, well-demarcated margin with a diffuse inner edge (erythema marginatum) unlike this patient's distinct macules. erythema marginatum (Choice B) Dengue virus is present in Costa Rica and can cause acute fever, rash, and joint pain. Leukopenia is typical, and bruising or bleeding often occurs due to thrombocytopenia. In addition, this child's prolonged symptoms make dengue virus unlikely. (Choice C) Malaria presents with intermittent fever, fatigue, joint pain, hepatosplenomegaly, and anemia. However, fevers are not associated with rash, and risk of malaria is very low in Costa Rica. (Choice D) Parvovirus B19 infection is an acute illness that presents with fever and rash (eg, "slapped cheeks," lacy truncal rash). Joint involvement can occur but is more common in adult women and resolves within 3 weeks. (Choice F) Systemic lupus erythematosus (SLE) can cause chronic fever, rash, joint swelling, lymphadenopathy, and hepatosplenomegaly. However, malar rash is typical, and SLE is unusual in children age <5. Educational objective: Systemic juvenile idiopathic arthritis is an autoinflammatory disorder of childhood characterized by arthritis for ≥6 weeks and fever for ≥2 weeks. Hepatosplenomegaly and lymphadenopathy are common, and quotidian fevers (spiking once daily) are often accompanied by an evanescent pink rash. References: Juvenile idiopathic arthritis. (http://www.ncbi.nlm.nih.gov/pubmed/22753788) Features distinguishing juvenile idiopathic arthritis among children with musculoskeletal complaints. (http://www.ncbi.nlm.nih.gov/pubmed/30498888)

A 4-Year-Old Boy Is Brought to the Emergency Department for Evaluation