Case history

An eight year old girl was admitted with a three day history of painful swollen joints. In particular, her ankles were swollen and her elbows were tender. That morning she had developed a purpuric rash over her lower limbs. She was afebrile. There was no previous history of a sore throat.

Questions

1. What is the diagnosis?
2. What is the differential diagnosis?
3. What are the other clinical features of this condition?

Answers

1. Henoch-Schönlein purpura.
2. Purpura are small circumscribed lesions caused by bleeding into the skin. Causes may be divided into thrombocytopenia, vascular defects, coagulation abnormalities, and drugs. Low levels of platelets (thrombocytopenia) may be caused by idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), or marrow disease such as leukaemia. Abnormalities of vessels include Henoch-Schönlein purpura, senile purpura, scurvy, uraemia, and gonococcal arthritis. Coagulation defects may be inherited or be due to disseminated intravascular coagulation (DIC). Iatrogenic causes include anticoagulation or steroids therapy.
3. Gastrointestinal pain and bleeding (85% have symptoms, 5% have major bleeds or intussusception), fever (75%), arthralgia (75% of children, especially involving the knees and ankles), glomerulonephritis (40%), and rarely stroke, testicular haemorrhage, and testicular torsion.

Discussion

Henoch-Schönlein purpura is a condition of unknown aetiology although it has been postulated that it may be a post-streptococcal phenomenon, and a history of an upper respiratory tract infection is found in two thirds of patients. Men are more commonly affected than women. The condition was first described in 1808 by Willan, but it was Eduard Heinrich Henoch, studying under Johannes Lucas Schönlein, Professor of Medicine, in Berlin, who reported the link between gastrointestinal symptoms and a purpuric rash in 1874. The majority of cases (75%) of the syndrome occur in children aged less than 10 years. The condition is a small vessel vasculitis characterised by a non-thrombocytopenic purpuric rash, occurring particularly over the buttocks and lower limbs.

Urine should be tested regularly for haematuria and proteinuria. Blood pressure, urea, and creatinine should also be mea- sured as markers of renal involvement. The full blood count should demonstrate a normal platelet count, and clotting studies should be normal. A blood film should help to exclude other important conditions such as leukaemia or TTP. IgA levels will often be raised and antistreptolysin titres (ASOT) may be suggestive of recent streptococcal infection. Treatment involves analgesia and steroid therapy if there is bowel involvement. Steroids are not used for renal involvement, and treatment for acute renal failure may be required. The prognosis of Henoch-Schönlein purpura is good, with less than 15% of those who had initial renal involvement going on to have further renal complications.