4. Case scenario
Yassin is a 9-year-old male child, who has been recently
abroad in a trip with his parents and a newborn sister.
After they are home, the parents expressed
constitutional and respiratory symptoms. Taking in
consideration the pandemic circumstances, they were
suspicious for COVID-19 infection. They seeked
medical advice and tested positive for the virus.
Fortunately, Yassin and his sis had no symptoms so they
were kept away from the parents for 14 days.
Two weeks after the family reunion, Yassin expressed
easily fatigability, palpitations and fainted once. The
mother noticed rash on his chest and red swelling of his
legs.
They visited the pediatrician, on examination he
detected cervical lymphadenopathy.
Considering the pandemic background, he requested a
COVID-19 swap for Yassin that came out positive.
5. Vasculitis
• Def: general term for vessel wall inflammation
• clinical features : depend on the vascular bed
affected (e.g., central nervous system vs. small
bowel).
• signs and symptoms :
➢Generally: include fever, myalgias, arthralgias, and
malaise.
➢Specifically: any organ can be affected; most
vasculitides involve small vessels, from arterioles
to capillaries to venules.
6.
7. etiology
The two most common pathogenic
mechanisms of vasculitis are :
• immune-mediated inflammation
• Infectious
infections can:
➢Directly by invading the vessel wall by
infectious pathogen
➢ Indirectly induce a noninfectious
vasculitis by generating immune
complexes or triggering cross-reactivity.
***In it is critical to distinguish between
infectious and immunological mechanisms,
because immunosuppressive therapy is
appropriate for immunemediated vasculitis
but could very well worsen infectious
vasculitis.
8. NONINFECTIOUS VASCULITIS
The main immunological mechanisms that
initiate noninfectious vasculitis are
(1) immune complex deposition,(eg SLE)
(2) antineutrophil cytoplasmic antibodies
(ANCA) e.g small vessle vasculitis,
(3) anti–endothelial cell antibodies (eg
Kawasaki disease).
(4) Autoreactive T cells cause injury to
vuscular endothelium, forming granuloma
e.g giant cell arteritis
9. 1- Immune Complex–Associated
Vasculitis.
• Many systemic immunological diseases, e.g:(SLE) and
polyarteritis nodosa, manifest as immune complex-
mediated vasculitis.
➢Circulating antigen-antibody complexes may also be
seen (e.g., DNA–anti-DNA complexes in SLE–
associated vasculitis
➢drug hypersensitivity. In some cases (e.g., penicillin)
➢vasculitis secondary to viral infections eg, polyarteritis
nodosa have an underlying hepatitis B infection.
10. 2- Antineutrophil Cytoplasmic
Antibodies.
• ANCAs are a heterogeneous group of
autoantibodies directed against constituents of
neutrophils
• previously classified according to their
intracellular distribution: cytoplasmic (c-ANCA) or
perinuclear (p-ANCA).
• now, they are discriminated based on their target
antigens: (Anti-myeloperoxidase, Anti-proteinase-
3)
11. ANCAs serve as useful diagnostic markers for the ANCA-
associated vasculitides
ANCA titers rise with recurrent disease and are
therefore useful in clinical management.
Although the precise mechanisms are unknown, ANCA
can directly activate neutrophils ------->stimulate
neutrophils to release reactive oxygen species and
proteolytic enzymes -----------> endothelial cell damage.
12. 3- Anti-Endothelial Cell Antibodies.
• Antibodies to endothelial cells may predispose to
vasculitides, e.g: Kawasaki disease, Henoch
schonlein purpura.
4-Autoreactive T cells cause injury to
vascular endothelium, forming granuloma
e.g: Giant cell arteritis
13. Diagrammatic representation of the typical vascular sites involved with the more common
forms of vasculitis, as well as the presumptive etiologies. Note that there is a substantial
overlap in distributions.
ANCA, antineutrophil cytoplasmic antibody; SLE, systemic lupus erythematosus.
