139: Systemic Necrotizing Arteritis Flashcards
What is the broad definition of vasculitis?
Vasculitis is defined broadly as inflammation of blood vessels, which can affect a single organ, particularly the skin, and is characterized by inflammation being a major, but not the only, pathologic process.
How are systemic vasculitides classified?
Systemic vasculitides are classified primarily by the size of the predominant vessel involved (small, medium, or large) and then further subdivided or grouped as appropriate.
What are the most widely used criteria for classifying vasculitis?
The most widely used criteria for classifying vasculitis include the classification criteria of the American College of Rheumatology and the disease definitions of the Chapel Hill Consensus Conference.
What is leukocytoclastic vasculitis?
Leukocytoclastic vasculitis does not refer to a specific disease but is a pathologic description that often, but not always, applies to vasculitis in the skin or other organs.
What demographic factors influence the occurrence of different forms of vasculitis?
Different forms of vasculitis show demographic variations, such as Takayasu arteritis being more common in females, Kawasaki disease primarily affecting young children, and Giant cell arteritis being limited to older adults.
What is the significance of demographic differences in vasculitides?
Demographic differences among vasculitides are of scientific interest as they provide clues to etiology and can assist in developing a differential diagnosis.
What role do genetic risk factors play in the epidemiology of vasculitides?
Vasculitides with strong regional variation have genetic risk factors in the HLA region, although these epidemiologic tendencies do not fully exclude the diagnosis of a specific form of vasculitis in any individual.
What is a common manifestation of vasculitis?
Skin disease.
What is the demographic characteristic of idiopathic vasculitis?
Considered rare and classified as ‘orphan’ diseases in the US.
Which demographic group is more affected by Takayasu arteritis?
Females more than males.
What age group is primarily affected by Kawasaki disease?
Young children.
What is a notable characteristic of giant cell arteritis?
It is limited to older adults.
In which regions is Behçet disease more common?
Countries in the Eastern Mediterranean, Japan, and Korea.
What factors influence the appearance of cutaneous vasculitis?
The appearance of cutaneous vasculitis reflects:
- Size and depth of the involved vessels
- Severity of inflammation and red blood cell extravasation
- Density of damaged vessels and resulting tissue destruction
How does vasculitis caused by immune complexes typically present on the skin?
Vasculitis caused by immune complexes in the dermal microvasculature often first appears as a tiny, bright red circle due to red blood cell extravasation. It becomes palpable once it reaches about 2 mm in diameter, and a high density of such lesions may produce areas of confluent purpura and/or central necrosis or ulceration.
What are the common presentations of small-vessel vasculitis in the skin?
Common presentations of small-vessel vasculitis in the skin include:
- Palpable purpura (classic presentation)
- Nonpalpable purpura (round or angular borders)
- Papules
- Urticarial lesions
- Nodules of different sizes and depths
- Bullous lesions
- Ulcers
- Edema in and near visibly affected areas
What symptoms may accompany purpura or livedo in vasculitis?
Purpura or livedo may be asymptomatic or produce pain that is often described as stinging or burning, but sometimes as itching. Nodules and ulcers are usually painful. Severe pain in a region not affected by nodules, ulcers, or confluent purpura should raise suspicion for neuropathy or inflammatory arthritis.
What are the two pathways involved in small-vessel vasculitides?
The two pathways involved in small-vessel vasculitides are:
1. Immune complex deposition: Immune complexes can form in response to microbes, autoantigens, or drugs, leading to activation of neutrophils and necrotizing vasculitis.
2. Non-immune complex mediated pathology: This likely involves ANCA, which activates neutrophils and contributes to necrotizing vasculitis.
What role do T cells play in large-vessel vasculitides?
In large-vessel vasculitides, T cells activate macrophages in the walls of large arteries. In conditions like Giant Cell Arteritis (GCA), IL-17-secreting (Th17) and interferon-γ-secreting (Th1) cells are prominent, and T cells enter the artery wall via the vasa vasorum, keeping the endothelium intact.
What is the significance of genetic factors in vasculitis?
Genetics appear to contribute modestly to ANCA-associated vasculitis, with identified genes associated with the specificity of the antibody to PR3 or MPO. In large-vessel vasculitides like GCA and Takayasu arteritis, genetics also contributes modestly via the HLA locus, indicating a potential genetic predisposition to these diseases.
What initial questions should be addressed when diagnosing vasculitis with skin lesions?
When a patient presents with skin lesions concerning for possible vasculitis, the following questions should be sought quickly:
1. Is the lesion due to vasculitis? This is often determined by skin biopsy, which is indicated in many cases of palpable purpura or other lesions when a diagnosis of vasculitis is not otherwise easily established.
What is the initial appearance of vasculitis caused by immune complexes in the dermal microvasculature?
It often appears as a tiny, bright red circle due to red blood cell extravasation.
What happens to lesions caused by immune complexes as they grow?
They become palpable once they reach about 2 mm in diameter.
What is a classic presentation of small-vessel vasculitis in the skin?
Palpable purpura.