A 7-year-old girl is brought to the emergency department by her father due to right hip pain. The patient first developed the pain yesterday after playing in the backyard. Her father placed ice on her hip, which initially helped, but after waking this morning, she refused to walk and now has pain in the left hip and left lower abdomen. The patient has no chronic medical conditions and takes no medications. Immunizations are up to date, and weight is at the 60th percentile. Temperature is 37.3 C (99.1 F), blood pressure is 94/66 mm Hg, pulse is 90/min, and respirations are 20/min. The patient is awake and alert. The oropharynx is clear. Cardiopulmonary examination is unremarkable. There is pain during passive range of motion of the right and left hips but no focal tenderness to palpation. Mild abdominal tenderness is present at the left lower quadrant. Several palpable petechiae are noted over the lower extremities. Complete blood count, coagulation studies, erythrocyte sedimentation rate, and urinalysis are normal. Which of the following is the best next diagnostic step in management of this patient?

Question

A 7-year-old girl is brought to the emergency department by her father due to right hip pain.  The patient first developed the pain yesterday after playing in the backyard.  Her father placed ice on her hip, which initially helped, but after waking this morning, she refused to walk and now has pain in the left hip and left lower abdomen.  The patient has no chronic medical conditions and takes no medications.  Immunizations are up to date, and weight is at the 60th percentile.  Temperature is 37.3 C (99.1 F), blood pressure is 94/66 mm Hg, pulse is 90/min, and respirations are 20/min.  The patient is awake and alert.  The oropharynx is clear.  Cardiopulmonary examination is unremarkable.  There is pain during passive range of motion of the right and left hips but no focal tenderness to palpation.  Mild abdominal tenderness is present at the left lower quadrant.  Several palpable petechiae are noted over the lower extremities.  Complete blood count, coagulation studies, erythrocyte sedimentation rate, and urinalysis are normal.  Which of the following is the best next diagnostic step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d73b_f3fc_bc81_e163eeb8d3db_MD0003_00 This patient's hip arthralgia, abdominal pain, and lower-extremity petechial rash are consistent with Henoch-Schönlein purpura (HSP), or IgA vasculitis, the most common vasculitis in children. Diagnosis of HSP is clinical. Palpable petechiae/purpura without thrombocytopenia or coagulopathy, as seen in this patient, is required for diagnosis plus ≥2 of the following: Diagnosis of HSP Arthritis/arthralgia, which most commonly affects the lower extremities and may cause refusal to walk in young children Colicky abdominal pain due to intestinal edema, which can also lead to nausea, vomiting, gastrointestinal bleeding, and intussusception Renal disease (hematuria ± proteinuria) In pediatric patients with classic findings, as seen in this girl, no additional diagnostic testing is required. In adults (in whom IgA vasculitis is rare) and in children with an atypical or incomplete presentation, skin biopsy is the next diagnostic step, revealing neutrophilic infiltration with IgA, C3, and fibrin deposition within postcapillary venules. Elevated serum IgA and low C3 may be seen in some patients, but these tests are nonspecific and of little diagnostic use. (Choice A) Anti-DNA antibodies are specific for systemic lupus erythematosus, which can cause arthralgias and petechiae. However, laboratory evaluation typically shows elevated erythrocyte sedimentation rate and complete blood count abnormalities (eg, anemia, leukopenia, thrombocytopenia), neither of which is seen in this patient. (Choice B) Echocardiography is part of the evaluation for acute rheumatic fever, a complication of group A Streptococcus pharyngitis characterized by migratory arthritis, carditis, erythema marginatum (annular, pink rash), subcutaneous nodules, and Sydenham chorea. This patient's rash is not consistent with rheumatic fever. (Choice D) Pelvic radiography is used to assess for hip pain caused by slipped capital femoral epiphysis, which typically presents in overweight adolescents, or Legg-Calvé-Perthes disease (idiopathic avascular necrosis of the femoral head). With both conditions, symptoms (eg, hip pain, limp) are typically chronic and not associated with abdominal pain or petechiae. (Choice E) Renal disease in HSP may not be initially evident, as in this patient with a normal urinalysis, but it can develop months after symptom onset. Serial screening urinalyses should be performed, but renal ultrasonography is not typically indicated in HSP management. Educational objective: Henoch-Schönlein purpura is an IgA-mediated vasculitis most commonly seen in children. Diagnosis is clinical, and no further testing is required in patients with palpable petechiae/purpura plus ≥2 of the following: arthralgia, abdominal pain, and renal disease. Skin biopsy is performed for atypical or incomplete presentations. References: Henoch-Schönlein purpura: a literature review. (http://www.ncbi.nlm.nih.gov/pubmed/28654132)

A 7-Year-Old Girl Is Brought to the Emergency Department by Her