Bone marrow necrosis and fat embolism syndrome in sickle cell disease: increased susceptibility of patients with non-SS genotypes and a possible association with human parvovirus B19 infection.

Fat embolism syndrome (FES) due to extensive bone marrow necrosis (BMN) in sickle cell disease (SCD) is a potentially under-diagnosed complication associated with severe morbidity and mortality. We identified 58 cases reported in the world literature to date. Typically, patients presented with a seemingly uncomplicated vaso-occlusive crisis (VOC) and subsequently deteriorated rapidly with a drop in their haemoglobin and platelets, development of respiratory failure, encephalopathy and varying degrees of involvement of other systems. Overall mortality in the reported cases was 64% but differed according to the use of transfusion and was 29%, 61% and 91% for patients receiving exchange, top-up or no transfusion respectively. Patients most at risk appear to be those with a "milder" form of SCD as 81% of patients had a genotype other than HbSS and the majority had no history of significant sickle-related complications. Human parvovirus B19 (HPV B19) infection was documented in 24% of cases.