By Gary M. White, MD
Small vessel vasculitis (SVV) is an inflammation of small vessels that often leads to the clinical appearance of palpable purpura and the histologic appearance of leukocytoclastic vasculitis (LCV). It has a myriad of causes although many cases are idiopathic. Cutaneous SVV is a term used to describe SVV without signs of systemic vasculitis. See also vasculitis.
A shower of purpuric lesions, both palpable and non-palpable, concentrated on the legs, occurs in the classic presentation of SVV. The patient often feels well, but fever, malaise, nausea, and arthralgias may be associated. Although larger lesions may occur including purpuric nodules, necrosis, ulceration, hemorrhage, bulla, EM-like lesions, these would suggest a larger vessel vasculitis. Acute, subacute, and chronic forms occur. Erythema elevatum diutinum, Henoch-Schonlein purpura, and urticarial vasculitis show LCV on biopsy. Systemic involvement should be considered including renal, GI, lung, and CNS. Erythema multiforme or septicemia with cutaneous lesions may be part of the differential diagnosis.
Often, the classic eruption of SVV comes and goes before a workup can be completed.
Many causes have been associated with this hypersensitivity vasculitis including inflammatory bowel disease, larger vessel vasculitis (e.g., PAN, Granulomatosis with polyangiitis), malignancy (e.g., lymphoma, myeloma, leukemia, solid tumors [e.g., ovarian JAAD 1999;40;287]), drugs (e.g., levamisole associated with cocaine use, Propylthiouracil can induce ANCA-associated microscopic polyangiitis or lupus-like disease, the nicotine patch [BJD 1996;134;361]), infection (e.g., urinary tract infection, Parvovirus B19, streptococcus, hepatitis B/C, mycobacterium leprae, Brucellosis), cryoglobulins, macroglobulinemia, collagen vascular disease (e.g., SLE, Sjögren's syndrome), rheumatoid vasculitis, chronic active hepatitis, and the food additive sodium benzoate [AD 1999;135;726].
A study of long distance walking [BJD 1996;134;91] found purpuric lesions may develop in athletes after prolonged exercise. Erythema, purpura, and urticaria of the lower legs was seen. LCV was found on biopsy of the purpura. Such changes were much more common in those with signs of chronic venous insufficiency. See exercise-induced purpura.
For the patient who presents with classic palpable purpura without obvious signs of systemic disease or cutaneous necrosis, the initial workup may be as minimal as a good HP, with emphasis on any new drugs, signs of infection (e.g., sore throat, fever, sinusitis, dental symptoms), OTC medications, lymph node exam, CBC, urine analysis, and stool for occult blood. However, if the disease becomes chronic, the patient is systemically ill, or the skin involvement is severe, workup may also include a skin biopsy (the best lesion to biopsy is a well-formed papule about 24 hours old) and the following laboratory data.
CBC, stool guaiac, creatinine, LFT's, urine analysis, RF, ASO, ANA, ANCA, SPEP, Hepatitis B and C, ELISA for parvovirus B19, complement levels, cryoglobulins, anti C1Q antibody and IgA-fibronectin aggregates (if available), and CXR. For the acutely ill patient, the most important entities to exclude are septic emboli as a cause (e.g., Neisseria, Staphylococcus, RMSF, Streptococcus, Pseudomonas, Candida). One may aspirate tissue fluid from an early lesion for gram stain and culture.
Of course, any primary disease, infection, etc., should be addressed and eliminated if possible. If a cause is identified and eliminated (e.g., drug, infection), milder cases may be observed expectantly. Prednisone is highly effective but has significant side effects. Other steroid-sparing agents may be used. Minocycline 100 BID was very helpful combined with low-dose prednisone in a patient with rheumatoid arthritis and LCV [AD 1997;133;15].
Colchicine has been recommended for patients with chronic, idiopathic LCV [AD 1998;134;355]. Dapsone may also be tried. Other options are every other day low-dose prednisone, weekly, low-dose methotrexate, mycophenolate mofetil, azathioprine (e.g., 2 mg/kg/day) and leflunomide [JAMADerm 2017;153;940].
In one study of LCV in children [JEADV 2017;31;544], 48% of cases were IgA vasculitis (Henoch-Schonlein purpura), 34% small-vessel vasculitis, 9% urticarial vasculitis, 7% ANCA-associated vasculitis and 2% acute hemorrhagic edema of infancy. IgA vasculitis was associated with abdominal pain, whereas non-IgA vasculitis was associated with headache.
Macular, purpuric almost targeted lesions.
Annular Leukocytoclastic Vasculitis
Vasculitis of the ankle (leukocytoclastic vasculitis on biopsy) in a patient whose SLE was flaring. Exam showed necrotic, vesicular lesions.
Leukocytoclastic vasculitis sparing a tattoo JAAD Case Reports September 2015 Volume 1, Issue 5, Pages 269–271
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