A 10-year-old male with a past medical history of attention deficit hyperactivity disorder presented with a 1-day history of acute left calf pain. Four weeks prior to admission, evanescent nonpruritic, nonerythematous nickelsize lower extremity nodules were noted following a transient nonspecific viral illness. Five days prior to development of calf pain, he was diagnosis with Henoch-Schönlein purpura (HSP) when he developed scattered nonthrombocytopenic lower extremity petechiae and mild abdominal discomfort. No specific therapy was prescribed. On the day of admission, he had been sitting stationary at a sporting event for 3 hours prior to the sudden onset of left calf pain, progressing to limp and swelling. There was no history of trauma. Family history was significant for the patient's mother experiencing 5 first trimester spontaneous abortions. She subsequently received heparin treatment during a future successful pregnancy. Further details of her evaluation were not available, although she recalled being told that she "might have a lupus anticoagulant." On arrival at the emergency department, laboratory studies where performed (Table 1), and lower extremity venous Doppler study demonstrated acute deep vein thrombosis of the left peroneal vein. Enoxaparin sodium therapy was initiated (1 mg/kg q12hr SQ) and he was admitted for further management. Petechial rash and extremity symptoms and signs readily improved over the next several days.An extensive evaluation initiated for hypercoagulability was completed. Studies are listed in Table 2.Genetic studies for factor V Leiden and prothrombin gene mutation were unremarkable; the patient was found to be doubly heterozygous for MTHFR C677T and MTHFR A1298C (with normal homocysteine level).Enoxaparin was discontinued after 3 months when a repeat Doppler study demonstrated complete resolution of thrombosis. At 2-month follow-up, factor VIII remained mildly elevated at 154%; lipoprotein A was elevated at 85.8 mg/dL. At 9-month follow-up, the child remained well.
DiscussionHSP is a well-characterized, multisystem, self-limited small vessel vasculitis mainly affecting children. The