HSP stands for Henoch Sconlein Purpura, which was the subject of a previous Ask the Doctor question. You can access that previous question and answer at http://www.irishhealth.com/askdoc03.html?f_qid=906. The cause of HSP is unknown but it usually occurs after a sore throat or other form of respiratory infection. In the majority of cases the condition fully resolves within a few weeks. However, recurrences are common and approximately 50% of people with HSP have one or more episodes of the condition. Most of these recurrences occur within a year of the first episode and they tend to be less severe than the initial event. There is no specific treatment for the condition and medical management is based on relieving any symptoms that may arise.