What Is Leukocytoclastic Vasculitis?
Leukocytoclastic vasculitis (LAV) is a rare but potentially life threatening disease caused by the clumping together of white blood cells. White blood cells are part of your body’s defense system against infection and other diseases. They help fight infections, kill invading viruses and bacteria, and protect you from other harmful substances such as toxins or radiation.
White Blood Cells are called leukocytes because they look like little white blood cells. There are two types of leukocytes: B lymphocytes and T lymphocytes.
These are the only two types of white blood cells that can cause disease; however, there may be others that have not been identified yet. Most people do not get sick from these other types of white blood cells. However, some people develop certain illnesses when exposed to them, such as pneumonia or meningitis.
The most common type of white blood cell is the B lymphocyte. Other types include the T lymphocyte, natural killer cells, granulocytes, dendritic cells, monocytes and eosinophils.
Some of these cells produce chemicals that attack bacteria and viruses. Others help clean up damaged tissue after an injury or surgery. Still others destroy foreign bodies such as cancerous tumors or infected wounds.
LAV is an uncommon disease that affects small blood vessels. Leukocytes become attached to the inside of the blood vessel and then release enzymes that destroy the innermost layer of the vessel wall, which is called the endothelium.
This causes the formation of an inflammatory mass (called a granuloma) around the leukocyte.
The white blood cell then dies and leaks its cellular contents into the vessel wall. The contents of the dead cell attract other white blood cells (mostly monocytes and neutrophils) to the endothelial site.
The increased number of white blood cells accounts for the intense inflammation seen in the affected blood vessel.
The leaking of cell contents is particularly damaging because it contains enzymes that can digest not only the endothelium lining of the blood vessel, but also nearby collagen and elastic fibers. This causes a loss of structural integrity in the blood vessel wall.
The long-term result is multiple tiny areas of damage that diminish blood vessel strength. These tiny areas of damage can eventually coalesce into a larger occlusive vascular disease process.
The causes of leukocyte attachment and activation in the blood vessel wall are not completely understood, but there are many theories:
The cause for the activation of the white blood cells in the first place seems to be a dysregulated inflammatory process. The immune system is supposed to be activated when there is an infection or other foreign substance.
However, in this case some external stimulus (virus, bacteria, etc.) has caused the white blood cells to activate for no reason.
There are probably genetic and environmental factors involved with this process; however, the exact causes are currently unknown. Some cases of LAV may be congenital (inherited).
Once activated, they begin secreting chemicals that damage the small blood vessels in the skin and elsewhere. They form a granuloma and die, leaking their cellular contents into the surrounding tissue.
Most people with leukocyte activation have no symptoms. The most common symptom is a small red bump on the skin which may itch or be painful.
It is usually only one bump and it can occur anywhere on the body, but most often occurs on the legs.
Less common symptoms are joint pain (often severe) and the development of ulcers on the legs. Many patients with leukocyte activation have minor complaints that come and go, such as headaches, low grade fevers, night sweats or undiagnosed skin rashes.
There is no real test for leukocyte activation; the diagnosis is made by exclusion when all other causes of a patient’s symptoms have been ruled out. Because the symptoms mimic many other diseases, such as other skin conditions, it is important to consult a medical specialist.
Although there is no cure for leukocyte activation, most patients respond well to treatment with non-steroidal anti-inflammatory drugs (NSAIDs), colchicine or steroids. There is ongoing research into better treatments.
Sources & references used in this article:
Cutaneous leukocytoclastic vasculitis associated with letrozole by A Digklia, E Tzika… – Journal of Oncology …, 2014 – journals.sagepub.com
Leukocytoclastic vasculitis (hypersensitivity vasculitis) by D Baigrie, JS Crane – 2019 – europepmc.org
Leukocytoclastic vasculitis associated with nontyphoidal Salmonella in a patient infected with human immunodeficiency virus by G Cornejo-Venegas… – … journal of STD & …, 2020 – journals.sagepub.com
Clinical approach to cutaneous vasculitis by MA Gonzalez-Gay, C Garcia-Porrua… – Current opinion in …, 2005 – journals.lww.com
Vasculitis—what do we have to know? A review of literature by E Shavit, A Alavi, RG Sibbald – The international journal of …, 2018 – journals.sagepub.com
Ritodrine-induced leukocytoclastic vasculitis in pregnancy by JC Cobeta-García, P García-Enguita… – Annals of …, 2004 – journals.sagepub.com
Leukocytoclastic vasculitis after high-dose methotrexate by M Navarro, R Pedragosa, A Lafuerza… – Annals of internal …, 1986 – acpjournals.org
Koebner phenomenon in leukocytoclastic vasculitis: A case report and an updated review of the literature by F Kassam, S Nurmohamed… – SAGE Open Medical …, 2019 – journals.sagepub.com