An 18-year-old woman presented with a 4-week history of a solitary painful bullous skin lesion over the lower right anterior tibia accompanied by generalized myalgia, polyarthalgia, joint stiffness, paraesthesia, and episodic ankle swelling. The lesion first appeared as a skin-coloredpapule and,within aweek, developedanerythematoushalo.Hermedical history includes asthma and acne. To our knowledge, there is no family history of this condition. Her medications included minocycline hydrochloride (for 25 months for acne), ranitidine hydrochloride, contraceptive pills, and iron supplements. An initial physical examination revealed mild synovitis in both ankles and an erythematous, raised papule overlying the distal aspect of the right anterior tibia. Treatment with prednisone acetate (10 mg daily) was initiated. Seven weeks later, the original skin lesion evolved into an ulcer with erythematous, raised borders (Figure 1). The case patient had new eruptions of nonindurated, violaceous, nontender, reticulated patches overlying the skin on the bilateral anterior tibias, consistent with livedo reticularis. She denies any previous episodes, and the results of a review of mitigating factors were negative. A laboratoryworkup revealed apositive antinuclear antibody 1:640nucleolar pattern, anelevatederythrocyte sedimentation rate, andelevatedC-reactiveprotein andserum IgG levels. The results of the following laboratory studies were negative or normal: complete blood cell count, urinalysis, liver profile, Lymedisease, parvovirus B19,Monospot test, uric acid, rheumatoid factor, antistrepolysin antibody, anti-Scl70, antihepatitis C virus, hepatitis B surface antigen, hepatitis B core antibody, cytomegalovirus antibody, and human T-lymphotropic viruses 1 and 2 antibody. Culture results of the skin lesion were negative. The results from chest radiography were normal. Figure 1.Ulcer with raised border and erythematous halo in distal right shin.