Snapshot A 56-year-old woman presents to her dermatologist’s office for a rash on both of her shins. She reports that this rash started a day ago and that her legs ache also. She has had low-grade fevers and some recent weight loss. Her past medical history includes diabetes, hypertension, and systemic lupus erythematosus, which was diagnosed a year ago but has not had a flare in over 6 months. On physical exam, she has bilateral symmetric non-blanching palpable purpura. Several lesions on her right shin have coalesced into violaceous plaques. She is started on steroids. Introduction Clinical definition leukocytoclastic vasculitis (LCV) an inflammatory small vessel vasculitis that affects the skin (cutaneous) and/or other organs (systemic) Epidemiology Incidence cutaneous LCV > systemic LCV Demographics female > male Location skin Etiology Idiopathic (50% of cases) Autoimmune disease (15-20% of cases) Drugs (i.e., levamisole-tainted cocaine) Infections (i.e., group A streptococcus, hepatitis B, or hepatitis C) Malignancy Pathogenesis immune complex deposition in small vessels causes complement activation this releases neutrophils and vasoactive amines, causing inflammation, vessel destruction, and extravasation of red blood cells the “violaceous” purpura is caused by this extravasation of red blood cells Associated conditions Henoch-Schönlein purpura occurs in children Presentation Symptoms rash occurs 7-10 days after infection, exposure to a medication, or 6+ months after onset of autoimmune disease occurs on dependent areas of the body, such as lower extremities maybe burning, painful, or pruritic systemic symptoms fever weight loss fatigue myalgias abdominal pain Physical exam symmetric, non-blanching, violaceous palpable purpura 1-3 mm in size lesions may coalesce and lead to plaques, nodules, and necrosis occurs on lower extremities and areas of pressure/trauma (i.e., sock lines and under compression devices) Studies Labs in cases in which the cause is unknown, patients often undergo autoimmune workup, including antinuclear antibody (ANA), rheumatoid factor (RF), antineutrophil cytoplasmic antibodies (ANCA), cryoglobulins, complement levels, and hepatitis serologies Skin biopsy of fresh lesions (24-48 hours old) histology “leukocytoclasis” describes neutrophilic infiltrate, along with granulocytic debris, fibrinoid necrosis of vessel walls, endothelial swelling, and extravasation of red blood cells direct immunofluorescence helps narrow down the differential diagnosis immune complex deposition in small vessel walls immunoglobulin (Ig) A suggests Henoch-Schonlein purpura IgM may suggest cryoglobulinemia C3 or IgG suggests systemic lupus erythematosus negative results may suggest pauci-immune vasculitides such as ANCA-vasculitis Differential Polyarteritis nodosa distinguishing factor a medium vessel vasculitis like polyarteritis nodosa presents with more subcutaneous nodules, livedo reticularis, retiform purpura, and significant ulcers DIAGNOSIS Making the diagnosis based on clinical presentation and laboratory studies Treatment Medical topical corticosteroids indication mild disease or single episode systemic corticosteroids indication severe or recurrent disease colchicine or dapsone indication patients who cannot receive corticosteroids, or if the disease recurs after steroid taper Complications Involvement of internal organs Prognosis Recurrence occurs in up to 10% of patients