Cutaneous small-vessel vasculitis

"Leukocytoclastic" (literally meaning 'leukocyte-destroying') refers to the damage caused by nuclear debris from infiltrating neutrophils in and around the vessels.

[6] Small fluid-filled blisters (or "vesicles"), pus-filled bumps resembling a pimple (or "pustules"), or shallow ulcers may also develop but are less common.

[6][5] The location of skin lesions varies but are most commonly found symmetrically below the waist, primarily on the buttocks and legs.

[5] Cutaneous vasculitis can have various causes including but not limited to medications, bacterial and viral infections or allergens.

[5] In cases where a cause can be determined, medications and infectious pathogens are most common in adults, while IgA vasculitis (Henoch–Schönlein purpura) frequently affects children.

[9] Once activated, neutrophils then release preformed substances, including enzymes causing damage to vessel tissue.

[10] The immune system senses these altered proteins as foreign and produces antibodies in efforts to eliminate them from the body.

[13] In the case that the cause is not obvious, a reasonable initial workup would include a complete blood count, urinalysis, basic metabolic panel, fecal occult blood testing, erythrocyte sedimentation rate (ESR), and C-reactive protein level.

[13] Small vessel cutaneous vasculitis is a diagnosis of exclusion and requires ruling out systemic causes of the skin findings.

[14] Skin biopsy (punch or excisional) is the most definitive diagnostic test and should be performed with 48 hours of appearance of the vasculitis.

Micrograph of cutaneous small-vessel vasculitis. The section shows all features of leucocytoclastic vasculitis. A mixed inflammatory cell population surrounding the postcapillary venules of the superficial dermis. The infiltrate consists of neutrophils with nuclear dust (dashed arrows) and shows high affinity for the vessels. Features of vascular injury are shown including fibrinoid necrosis (asterisks) and erythrocyte extravasation (solid arrows). [ 11 ]