Unusual cutaneous lesions indicating fat embolism syndrome in homozygous sickle cell disease
Authors: Claude Bachmeyer, François Lionnet, Katia Stankovic Stojanovic, Philippe Moguelet, Sélim Aractingi
Journal: American Journal of Hematology (2013)

A 26-year-old Algerian man with homozygous sickle cell disease (SCD) was admitted for acute chest syndrome (ACS). Vital signs were unremarkable and serum lactate dehydrogenase (LDH) level was 346 U/L (normal < 250). Chest X-ray showed a consolidation in the right lower lobe. Usual treatment of ACS resulted in rapid improvement. Six days later, temperature rose to 39°C with chills and exacerbated pain in both legs and lower back, rapidly becoming diffuse and intense. Blood cell count showed a decrease in hemoglobin level of 3 g/dL and a low reticulocyte cell count while leukocyte cell count increased to 45,000/mm3 with leukoerythroblastosis. The LDH level rose to 7,000 IU/L and ferritin level reached 20,247 µg/L (normal < 300). Bone marrow smear disclosed marrow necrosis featured with ghost cells associated with erythrophagocytosis (Image 1A). IgM anti parvovirus B19 antibodies were detected in serum and parvovirus B19 DNA was present in serum and bone marrow. A first partial exchange transfusion with two red cell packs was performed. Three days after, five painful and tender, erythematous plaques 1–3 cm in diameter developed on the legs (Image 1B). Histological examination of one of these lesions disclosed a superficial venous thrombosis in the upper subcutaneous tissue. The occluded vessel contained lipid vacuoles as well as sickle cells and was surrounded by an inflammatory infiltrate (Image 1C,D). Transthoracic ultrasound examination confirmed the absence of patent foramen ovale. Clinical neurological examination and renal function were both normal. A second partial exchange transfusion with two red cell packs was done. The S hemoglobin level decreased afterwards to 39%. Progressive clinical improvement was observed and cutaneous lesions disappeared within 7 days. The patient remained healthy up to date. SCD complications are induced by polymerization of the HbS containing erythrocytes resulting in capillaries obstruction with decrease in blood flow to peripheral organs 1, 2. Fat embolism originating from focal bone marrow necrosis is frequently suspected to participate in ACS pathogenesis 1-3. In contrast, fat embolism syndrome is a rare but life-threatening complication in SCD, possibly responsible for multiorgan failure 1-4. In the case described here, the clinical presentation was surprising, since classical skin lesions associated with fat embolism syndrome were until now described as petechial papules or plaques 4. Of note patients with SCD may develop papules and plaques related to thrombosis due to sickled red blood cells 5. In several cases, bone marrow necrosis has been reported to be associated with parvovirus B19 infection as in our patient 2, 4, 6. Because of poor prognosis of fat embolism syndrome occurring when aplasia and multiorgan failure have developed, early diagnosis and treatment—relying on exchange transfusion—are recommended 2, 4. The diagnosis should be suspected when leukocytosis with leukoerythroblastosis, relative reticulocytopenia, in association with signs of erythrophagocytosis (extremely elevated serum LDH and ferritin levels) are found. Indeed, these hematologic abnormalities are not encountered in other complications in SCD. Hematological signs should evoke bone marrow necrosis in SCD, even when the clinical presentation is unusual, leading to prompt diagnosis and treatment. Furthermore, skin biopsy is another diagnostic tool that should not be neglected.