what are the complications of HSP??

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Henoch-Schonlein purpura, also known as anaphylactoid purpura, is a disease characterized by an inflammation of the body's smallest blood vessels throughout the body. While the cause is unknown, it seems to be triggered by a recent respiratory infection, either viral or streptococcal. Children ages two to ten (particularly boys) are most commonly affected, although the condition can develop in adults as well. The older the child (or adult), the more likely the disease is to be serious.
The disease may begin suddenly, with rash, abdominal pain, and other signs, or it may develop more slowly over a period of weeks. Henoch-Schonlein purpura is characterized by:
·A rash, which is always present, begins with small hives, or red patches, which appear anywhere on the body, but especially on the legs and buttocks. This rash represents swollen blood vessels, and the spots blanch with pressure, since pressure moves the blood along the vessel. The allergic nature of the rash often makes it itch. As time passes, blood leaks from the swollen vessels, the rash changes from red to a bruised, purple color (hence the name purpura), and the rash no longer blanches when pressed. As the tiny bruises heal they turn to a rust color, and then fade. Each spot lasts for about five days. Often the rash comes in several crops, and a single child may have a rash of a variety of different colors. The skin rash is the most obvious, and most common, finding in Henoch-Schonlein purpura - but by no means the most serious. Blood vessels in other parts of the body can also be involved --most frequently in the joints, the intestines, and the kidneys.
 ·Joint symptoms (arthritis) occur in two thirds of the children. The knees and ankles, particularly, often become swollen, tender, and painful with movement. This arthritis can be quite debilitating, but usually resolves in just a few days. No permanent deformity results, even with the most severe arthritis.

key points: Henoch-Schonlein purpura is a short term inflammation of certain blood vessels thought to be triggered by a malfunction of the immune system. Symptoms include a purple spotted skin rash, abdominal pain swollen painful joints, and gastrointestinal upsets such as diarrhea. Children (particularly boys) are most commonly affected, although the condition can develop in adults too. In most cases, the symptoms disappear by themselves within one to four weeks.

• ·Gastrointestinal symptoms occur because of inflammation of the blood vessels of the GI tract. Most of these children experience abdominal pain, often quite severe. They will often vomit -- sometimes vomiting blood. More than half of the children with Henoch-Scholein  will have bloody stools. Serious short-term complications most often come from the GI involvement. of pain and gastrointestinal bleeding, with possible complications of bowel rupture or intussusception
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• ·Kidney disease occurs in up to half of affected children, usually manifest by blood and protein in the urine. While more severe kidney involvement can occur and may even become more or less permanent, most children with kidney involvement recover fully. A very few do not clear up fully and may go on later to develop more serious chronic kidney disease.

·Angioedema - massive transient swelling of the scalp, eyelids, lips, ears, backs of the hands and feet, back, scrotum, and perineum is common and may be striking, especially in young childrenMost children recover fully. The disease may be quite mild and last only 2 or 3 days. For those with moderate to severe symptoms, though, the disease lasts an average of 4 to 6 weeks, with relapses occurring up to a year later (particularly after the child gets another cold or is re-exposed to the offending agent).
Rarely, children die from complications experienced near the time of diagnosis (bowel perforation, hemorrhage, seizure, stroke, etc.). Having made it through the acute crisis, the long-term outcome depends on the extent of kidney involvement. With no kidney involvement, full recovery is the rule. One-fourth of the children with kidney problems will still have detectable problems years later. 
There is no specific treatment for HSP. If the initiating trigger is identified, everything possible should be done to remove it. If the cause is thought to be a bacterial infection, such as Strep throat, prophylactic antibiotics are often given once the infection is eliminated, to prevent recurrence. Anti-inflammatory drugs, and sometimes immunosuppresive drugs, are used to provide much-needed symptomatic relief. Steroids may cause dramatic reversal of GI or brain involvement, but have not been shown to be very effective for the kidneys.

HSP is a very serious disease. Thankfully, it is also very uncommon.