Vasculitis allergica, also known as Schoenlein-Henoch purpura, is an inflammation of small and medium-sized vessels in various organ systems caused by an immune reaction. Preferably occurring during the cold season, the disease usually begins one to three weeks after a previous upper respiratory tract infection and primarily affects preschool and school-aged children or adolescents. The disease is also occasionally observed after medication, occurring slightly more often in boys than in girls.
Allergic overreaction of the immune system as a cause
Vasculitis allergica is thought to be caused by an allergic overreaction of the immune system, which may be caused by various foreign proteins (antigens). Most often, these antigens enter the body as components of pathogens, but contact is also possible as part of medications or insect venoms.
The immune system reacts with the formation of IgA antibodies, which agglomerate with the antigens to form immune complexes. Their deposition in vessel walls triggers the aforementioned inflammatory reaction, which results in increased permeability of the vessels in various organs. The event becomes visible in dot- to coin-sized skin hemorrhages.
Symptoms in various organs
The disease process in the vessels can cause symptoms in several organ systems in vasculitis allergica:
- Skin: conspicuous reddish-brown palpable skin hemorrhages (purpura) are regularly found, usually symmetrically arranged, especially on the extensor sides of the legs and buttocks. The itchy spots and papules often flow into each other and can range from pinhead to coin size.
- Joints: many children suffer temporarily from painful swelling of the ankle and knee joints and suddenly do not want to walk.
- Intestine: Due to inflamed vessels of the small intestine, more than half of the children complain of colicky abdominal pain, accompanied by nausea and vomiting. These complaints are often accompanied by bloody-mucous stools.
- Kidneys: In about 30 percent of sufferers, the kidney vessels are also affected, which is often only noticeable after two to three weeks by detection of blood and protein in the urine (so-called Schoenlein-Henoch nephritis).
The symptoms of vasculitis allergica are usually preceded by a general feeling of illness and mild fever.
Clinical picture leads to the diagnosis
There is no specific laboratory test as evidence of vasculitis allergica. However, the physician can usually make the diagnosis based on the characteristic skin symptoms in conjunction with previous infection or medication. Sometimes detection of immune complexes circulating in the blood is successful.
It is not uncommon for symptoms of the intestinal tract to precede skin symptoms, making diagnosis more difficult. Further guidance may be provided by ultrasonography of the abdomen and examination of the stool to detect blood. Repeated urine tests are also needed to detect kidney involvement.
Therapy of vasculitis allergica
In the acute phase of the disease, bed rest is prescribed. In a large proportion of sufferers, the symptoms improve without further treatment. If joint symptoms are severe, nonsteroidal anti-inflammatory drugs are administered for relief, and in the case of intestinal involvement, cortisone preparations are used for treatment.
If kidney involvement has been present for a long time, a tissue sample can provide information about the extent of the damage. Therapy with drugs to suppress the immune system (immunosuppressants) and cortisone may then be indicated.
Relapsing course is characteristic
The relapsing course with recurrent abdominal pain and skin bleeding is typical of Schoenlein-Henoch purpura. In most cases, the disease is benign and healed after a few days, but at the latest after four to six weeks. Occasionally, however, the symptoms may recur for months or years.
In rare cases of intestinal involvement, a section of the intestine may be invaginated. The development of chronic kidney inflammation with deterioration of kidney function is particularly feared.
