Leukocytoclastic vasculitis flare; Leukocytoclastic vasculitis flare; This is a literature report entitled Leukocytoclastic vasculitis flare following the COVID-19 vaccine.   The authors reported a case of a patient who suffered from vasculitis after COVID-19 vaccination. A 46-year-old female presented to the Department of Dermatology with a past medical history of psoriasis, psoriatic arthritis, irritable bowel syndrome, and Leukocytoclastic vasculitis. The diagnosis of her vasculitis was biopsy-proven with unremarkable laboratory exams including complete blood count, liver function test, hepatitis B and C serologies, and QuantiFERON-TB Gold. The vasculitis was successfully treated with a prednisone taper. The patient denied any flares for 2 years until she received the BNT162b2 mRNA COVID-19 vaccine. Within 2 days, she noted a mild exacerbation of her palpable purpuric papules on the bilateral lower legs. Clinical differential diagnosis includes small vessel vasculitis such as IgA vasculitis. The vasculitis stabilized, and 2 days after the second dose of the vaccine, it exacerbated again with significant exquisitely tender palpable purpuric papules distributed bilaterally on the lower legs, feet, upper extremities, lower back, and abdomen. No systemic involvement or manifestation was perceived. After discussing risks and benefits, particularly of potential lowered vaccine efficacy, the patient was prescribed topical steroids and a prednisone taper. Vasculitis precipitation or exacerbation has been reported secondary to multiple vaccines such as the influenza virus, hepatitis B virus (HBV), Bacille Calmette-Guerin (BCG), and human papillomavirus (HPV). However, this was rare and the relationship between immunizations and vasculitis has yet to be determined. A possible mechanism for the exacerbation may be similar to the one hypothesized about the influenza vaccine, which can cause vessel damage likely secondary to abnormal immunological activation with vaccine-related antigens promoting antibody development and immune complex deposition. The COVID-19 virus may provoke hyperactivation of the immune system secondary to cross-reactivity and molecular mimicry between the virus and self-antigens, consequently triggering autoimmune disorders such as vasculitis, antiphospholipid syndrome, immune-mediated myositis, and myocarditis. Before the COVID-19 vaccine became available, it was suspected that a similar scenario might happen following its administration. It is notable that despite a diagnosis of psoriasis and psoriatic arthritis, the patient had no exacerbation in these T helper 17 (Th17)-mediated diseases. Our patient was prescribed a prednisone taper. There was concern regarding prescribing such immunomodulatory agents shortly after vaccines. However, it has been reported that systemic steroids cause variable effects on immunity, which was dose dependent. Up to 20 mg/day of prednisone seemed to not have any effect on patient's immune response to vaccines. For the COVID-19 vaccine, it was speculated that regardless of the type of vaccine, systemic corticosteroids have no or minimal risk in patient's immune response. It was important for healthcare providers and patients to be aware that the COVID-19 vaccine can potentially precipitate or exacerbate cutaneous inflammation. When it comes to therapeutic options of such events, it will depend on a case-by-case basis to decide what is in the best interest of the patient.  Histopathologic photomicrographs, H&E stain: Sections show a perivascular mixed inflammatory infiltrate with numerous neutrophils, lymphocytes, and occasional eosinophils. There is leukocytoclasia and erythrocyte extravasation, but fibrinoid necrosis of vessels is not observed. (a) Magnification at x4, (b) magnification at x10, and (c) magnification at x40.  Leukocytoclastic vasculitis after first dose of COVID-19 vaccine. Palpable purpuric papules distributed on bilateral lower legs. Leukocytoclastic vasculitis after second dose of COVID-19 vaccine. Widespread palpable purpuric papules and plaques distributed on bilateral legs and feet. Leukocytoclastic vasculitis after second dose of COVID-19 vaccine. Closer look to widespread palpable purpuric papules and plaques located on the right lateral anterior lower leg.  No follow-up attempts are possible, Information about batch number cannot be obtained. No further information is expected.; Sender's Comments: Based on the information available , a possible contributory role of the suspect BNT162B2 cannot be excluded for the reported events of Leukocytoclastic vasculitis flare up. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate