What is responsible for the asymptomatic eruption on her legs?

A 54-year-old female presents with an asymptomatic eruption on her legs. She is otherwise healthy with no new medications or exposure history. She denies fever, cough, joint or muscle pain, headaches, or visual changes. 

What is responsible for the asymptomatic eruption on her legs?

A. Cutaneous lupus erythematosus
B. Atopic dermatitis
C. Psoriasis
D. Leukocytoclastic vasculitis
E. Polymorphous light eruption

(Answer and discussion on next page)

Answer: Leukocytoclastic vasculitis 

This patient had confirmed leukocytoclastic vasculitis by skin biopsy. Subsequent evaluation and workup did not reveal any cause for her vasculitis. She was given a short 9-day prednisone taper with complete resolution. All lab work came back normal. She still has not relapsed. She was suspected to have leukocytoclastic vasculitis rather than the other potential diagnoses because of the presence of purpuric lesions.