Vasculitis is an inflammatory disorder which affects the wall of blood vessels in the skin. It may be classified based on the type of vessel involved, as small vessel, medium-vessel and large vessel vasculitis. The inflamed vessel wall undergoes destruction by the inflammatory infiltrate, resulting in any of the following:
- hemorrhage from the disrupted blood vessel
- aneurysm of the weakened wall
- hyperplasia of the intimal and medial layers leading to vessel narrowing
- ischemia or infarction of the skin supplied by it
The skin is often involved in vasculitic syndromes, because it is so large and so richly supplied with blood vessels. Furthermore, it is exposed to low temperatures and is subject to the stagnation of blood by pressure and by gravity-dependent stasis. Thus it is peculiarly susceptible to vasculitis, whether primary or secondary as in hepatitis C and other infections, serum sickness, autoimmune disorders or malignant neoplasms.
Cutaneous vasculitis is either confined to the small vessels of the skin (capillaries, post-capillary venules, and arterioles), or may affect medium-sized or larger vessels.
The symptoms of cutaneous vasculitis range over a wide variety:
- superficial small vessel involvement producing palpable purpura, petechiae, or urticaria
- deeper involvement of dermal or subcutaneous muscular vessels manifesting as nodular red areas, livedo racemosa, hemorrhagic vesicles, ulcerated areas or gangrene of a digit
- both dermal and subcutaneous vessel involvement in connective tissue disorders, Behçet disease, or ANCA-associated vasculitis (among others)
- fever, arthralgia and symptoms of organ involvement in secondary cutaneous vasculitis, such as shortness of breath or cough with pulmonary lesions, hypertension in renal disorders, or blood in stool in the case of intestinal involvement
Cutaneous vasculitis may be primary or secondary. It is a part of many systemic vasculitides, such as:
Diagnosis and treatment
Diagnosis of the cutaneous vasculitis depends on the biopsy taken. An adequate biopsy includes subcutaneous tissue as well as skin, and should be taken from the most painful or newest lesion. Characteristic biopsy findings in acute vasculitic lesions include inflammatory infiltrate in the vessel wall and fibrinoid necrosis, with red cells being seen outside the vessel wall and leukocytoclasis, or nuclear debris from the breakdown of white blood cells. In more chronic lesions, fibrotic scars formed by obliterated arteries are the only sign of destroyed blood vessels.
In addition, direct immunofluorescence helps to distinguish the deposited immunoglobulin as IgA, as in Henoch–Schönlein purpura, or IgG/IgM. It is necessary to rule out syndromes which mimic vasculitis, such as thrombosis due to the anti-phospholipid antibody syndrome. Other tests include cryoglobulins, ANCA, C3/C4 levels, and rheumatoid factor testing, among others.
Cutaneous vasculitis is usually self-limited, being confined to a single episode. Treatment includes:
- avoiding triggering factors, such as prolonged standing posture, some infections and some drugs
- elevation of the affected leg
- rest from the standing position
- loose-fit clothes
- avoiding exposure to cold
- NSAID (non-steroidal anti-inflammatory drug) therapy
Other medications appropriate for treatment of mild cutaneous vasculitis, especially when it recurs or fails to respond to symptomatic measures, include:
For more severe cutaneous disease, treatment includes:
- Systemic corticosteroids
- Immunosuppressive drugs such as the antimetabolites azathioprine and methotrexate
More intractable cutaneous vasculitis may require a combination of these. Newer options include
- Intravenous immunoglobulin
- Biologic modulators such as infliximab (a TNF-α inhibitor) or rituximab (anti-B-cell antibody)