Type 2 Leprosy Reaction Mimicking Leukocytoclastic Vasculitis in a Postpartum Patient

Leprosy is a disease caused by Mycobacterium leprae that, depending on a patient's baseline susceptibility and immune system function, can present in a wide variety of ways. The host's immune system response to the infection can be cell-mediated or humoral and can be further altered by changes in immune function or treatment. Depending on the time at which a skin biopsy is taken from affected areas, different inflammatory cell types are present, and the histopathology can mimic that of other infectious, autoimmune, or malignant entities, especially when the clinical information provided is vague. We present a case of a 24-year-old Micronesian woman who initially presented immediately postpartum with clinical and histopathological findings suggestive of urticarial vasculitis, but a subsequent biopsy resulted in a diagnosis of erythema nodosum leprosum reaction and borderline multibacillary leprosy. This case illustrates an unusual clinical and histological presentation of M. leprae and highlights the importance of clinical history.