Cutaneous vasculitis

[Agnes]

Cutaneous vasculitis refers to vasculitis affecting small- or medium-sized vessels in the skin and subcutaneous tissue but not the internal organs. Cutaneous vasculitis may be limited to the skin, or may be a component of a systemic primary or secondary vasculitic disorder. Purpura, petechiae, or ulcers may develop. Diagnosis requires biopsy. Treatment depends on etiology and extent of disease.
(See also Overview of Vasculitis.)
Vasculitis can affect the small- or medium-sized vessels of the skin. Vasculitis affecting the small vessels of the skin (eg, arterioles, capillaries, postcapillary venules) tends to cause lesions such as purpura, petechiae, and possibly shallow ulcers. Livedo reticularis, nodules, and deep ulcers are usually caused by vasculitis of deeper, medium or large vessels. Any primary or secondary vasculitis can affect the skin, including that due to serum sickness, infections (eg, hepatitis C), cancers, rheumatologic or other autoimmune disorders, and hypersensitivity to drugs.
Terms used to describe cutaneous vasculitis can overlap and have been used inconsistently in the literature:

Cutaneous vasculitis: This term describes vasculitis that affects the skin but not the internal organs.
Cutaneous small-vessel vasculitis (CSVV): This term describes vasculitis that affects the small vessels of the skin but not the internal organs. CSVV sometimes refers to small-vessel vasculitis of unknown cause (also called idiopathic cutaneous small-vessel vasculitis).
Leukocytoclastic vasculitis: This term describes a common type of CSVV, so-called because inflammation consists initially of neutrophils, which after degranulation result in deposition of nuclear debris (leukocytoclasis) in the vessel wall.
Hypersensitivity vasculitis: This term previously used to mean CSVV but is now usually not used because the cause of CSVV is usually not hypersensitivity. However, hypersensitivity vasculitis is sometimes used to refer to CSVV caused by a known drug or infection.