A 2-month-old African American boy is brought to the emergency department due to persistent crying. Last evening, the infant began crying after his mother lifted his legs to change his diaper. Overnight, the patient was intermittently fussy and refused to breastfeed, and he has been difficult to console this morning. He was born at term via cesarean delivery due to breech presentation and was discharged on day of life 2. Temperature is 38.5 C (101.3 F). Cardiopulmonary examination is normal. The liver edge is 1.5 cm below the costal margin. Bilateral testicles are present and nontender. The right hip is held flexed, abducted, and externally rotated. The patient cries with palpation of the upper right thigh and resists movement along that hip. The left hip has full range of motion. Laboratory results are as follows: Which of the following is the most likely diagnosis in this patient?

Question

A 2-month-old African American boy is brought to the emergency department due to persistent crying.  Last evening, the infant began crying after his mother lifted his legs to change his diaper.  Overnight, the patient was intermittently fussy and refused to breastfeed, and he has been difficult to console this morning.  He was born at term via cesarean delivery due to breech presentation and was discharged on day of life 2.  Temperature is 38.5 C (101.3 F).  Cardiopulmonary examination is normal.  The liver edge is 1.5 cm below the costal margin.  Bilateral testicles are present and nontender.  The right hip is held flexed, abducted, and externally rotated.  The patient cries with palpation of the upper right thigh and resists movement along that hip.  The left hip has full range of motion.  Laboratory results are as follows:  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d743_6e1c_bc81_1708f605883b_MD0003_00 This infant with fever, pain with hip movement, and leukocytosis likely has septic arthritis. This joint infection most commonly occurs in healthy children age <4 via hematogenous spread of bacteria. Staphylococcus aureus is the most common pathogen, but group B Streptococcus and gram-negative bacilli (eg, Klebsiella pneumoniae, Escherichia coli) also occur frequently in children age <3 months. Presentation classically includes acute onset of fever, monoarticular joint pain, and inability to bear weight. In infants, symptoms may be nonspecific, including fever, inconsolability, and poor feeding, as in this case. Subtle signs of joint involvement (most commonly knee and hip) in infants include lack of movement of the affected side ("pseudoparalysis") and excessive fussiness during diaper changes or repositioning (as seen here). Infants often lie with the affected hip flexed, abducted, and externally rotated to maximize joint space and comfort. Physical examination may reveal pain with active or passive motion as well as asymmetric swelling. flexed, abducted, and externally rotated Supportive findings include leukocytosis with neutrophilic predominance and elevated inflammatory markers (eg, C-reactive protein, erythrocyte sedimentation rate). Management includes joint aspiration and prompt initiation of antibiotics. (Choice A) Leukemia can present with bone pain, fever, and leukocytosis. However, thrombocytopenia and/or anemia would be expected. This patient's hemoglobin is normal for age (ie, physiologic nadir), and the platelet count is normal. (Choice B) In young infants, developmental dysplasia of the hip presents with hip instability (eg, abnormal Ortolani and Barlow tests) and asymmetric thigh creases. Irritability, fever, and leukocytosis are not seen. hip instability asymmetric thigh creases (Choice D) Sickle cell pain crises can present with severe bone pain due to vasoocclusion by sickled red blood cells. These episodes typically begin as early as age 6 months when the production of defective hemoglobin A increases. A 2-month-old's hemoglobin is primarily fetal hemoglobin, making a pain crisis unlikely. (Choice E) Transient synovitis typically presents in well-appearing children with hip pain after a recent viral illness. Patients are usually school-aged (not infants), and leukocytosis is not seen. Educational objective: The presentation of septic arthritis in infants can be subtle and may include fever, lack of movement of the involved joint, excessive fussiness (eg, during diaper changes), or asymmetric swelling. References: Bone and joint infections in children: septic arthritis. (http://www.ncbi.nlm.nih.gov/pubmed/26189923)

A 2-Month-Old African American Boy Is Brought to the Emergency