A 66-year-old man with a 7-year history of untreated paroxysmal nocturnal hemoglobinuria (PNH) reported new onset fever, malaise, joint pains, and skin rash (panel A). Hemoglobin was 7.8 g/dL, reticulocytes were 3.1%, and platelets were 26?000/mm3. No spherocytes or schistocytes were observed in the peripheral smear, and the lactase dehydrogenase (1638 U/L) was consistent with ongoing hemolysis. Urinalysis showed large amount of “blood” by dipstick, but only 6 red blood cells per high-power field, consistent with hemoglobinuria. Ninety-eight percent of granulocytes showed low expression of CD16 and an absence of expression of CD66b; the rest was negative for both markers. Five percent of red cells was negative for CD55 and CD59 (type III). There was no evidence of disseminated intravascular coagulation, lupus anticoagulant, or deficiency of protein C or S. He was treated empirically with antibiotics; however, the skin rash spread rapidly to his entire back, extremities, and buttocks (panel B). Hemolysis, thrombosis, and bone marrow failure are features of PNH. Thromboses can occur in unusual sites, including dermal vessels. This patient’s thromboses were confined to the skin and characterized by central necrotic lesions with surrounding erythema and evolving into bullae (panel C). A heparin drip was started on day 3, and a rapid beneficial response was seen (panel D). Biopsy confirmed dermal vessel thromboses (panel E, arrows). A meningococcal vaccine was administered in preparation for eculizumab. A similar pattern of dermal thrombosis has been reported (Arch Dermatol. 1978;114[4]:560-562; Br J Haematol. 2007;137[4]:271).