Leucocytoclastic vasculitis can be due to flu vaccine. This is the most common form of vasculitis that exclusively affects capillaries and venules, almost invariably involves the skin. It is frequently associated with immune complex deposition (with underlying infections, drugs, malignancy, collagen vascular disorders, etc). This form of vasculitis has also been termed as hypersensitivity vasculitis. This small vessel vasculitis may be limited to the skin or may be associated with visceral involvement including pulmonary hemorrhage, intestinal ischemia or hemorrhage, and glomerulonephritis. Visceral involvement may or may not be part of the syndrome of Henoch-Schonlein purpura (HSP), which occurs in adults as well as children and is usually associated with vascular and renal deposition of IgA-containing immune complexes.
Common manifestations include purpura and/or urticaria, abdominal pain, gastrointestinal bleeding or intussusception, arthralgias, arthritis or periarthritis, and glomerulonephritis. Visceral symptoms may precede the skin lesions, leading to diagnostic confusion. Purpura tends to occur in crops of lesions of similar age. Palpable purpuric lesions are generally more pronounced in gravity-dependent areas like legs. Papules, urticaria/angioedema, pustules, vesicles, ulcers, necrosis, and livedo reticularis may be seen.
The collagen vascular disorders and various other causes need to be ruled out by investigations. Consult a Medicine specialist and dermatologist.