A 24-year-old white woman presented to the emergency department with a 3-day eruption on her lower extremities. Her medical history was remarkable for paroxysmal nocturnal hemoglobinuria that had been diagnosed 10 years earlier; frequent transfusions have been required for this condition, with the last one being administered 10 days before presentation. She frequently developed hives after transfusion and thought that the present eruption was a variant of her usual hives. Petechiae initially developed on her right ankle, followed by scattered purpuric patches on her left ankle and shin.
Berlin JM, Queen JR. Lower Extremity Purpura. Arch Dermatol. 2002;138(6):831-836. doi:10.1001/archderm.138.6.831