Fat embolism syndrome in 4 patients with non-HB ss sickle cell disease

NMUH Staff Publications

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101

<span style="font-size: 10pt;"><span style="color: #4a4a4a; font-family: Lato, "Helvetica Neue", Helvetica, Arial, sans-serif; text-decoration-color: initial;">Background: Fat embolism secondary to bone marrow necrosis may occur in patients with sickle cell disease giving rise to respiratory, neurological and haematological complications - the so-called fat embolism syndrome (FES). FES is more common in non-SS genotypes. Aims: We present 4 recent cases of suspected or confirmed FES in adult patients with Hb SC seen in our hospitals and review the clinical, radiological and histological findings of this under-recognised and potentially devastating complication of 'milder' forms of sickle cell disease. Methods: Case 1. A 53 year old man with Hb SC was admitted with malaise, fevers and rigors. The following day he dropped his GCS and was transferred to ITU. MRI brain showed widespread small infarcts. He became pancytopenic. Bone marrow examination showed widespread necrosis. Follow-up MRI showed multiple microhaemorrhages. Despite supportive care including top up transfusions he retained a major neurological deficit. Case 2. A 50 year old woman with Hb SC was admitted with abdominal and joint pain. That evening, she deteriorated with hypoxia, pyrexia and tachycardia. CT showed no major PE. She was given antibiotics and transferred to ITU where exchange transfusion was initiated. A drop in the platelet count was noted. She suffered a cardiac arrested and died. At post mortem pulmonary fat embolism was found. Case 3. A 56 year old man with Hb SC was admitted with body pain and breathing difficulties and deteriorated within hours. Chest x-ray showed bilateral haziness. Despite antibiotics he deteriorated further with a fall in GCS and acute kidney injury and was transferred to ITU before being exchange transfused. CT showed cerebral oedema. An MRI performed a few days later showed numerous widespread small haemorrhagic foci. GCS remained low despite removal of sedation. Case 4. A 30 year old man with Hb SC was admitted with leg and arm pain. Over the following days he complained of back pain of an unusual severity. On the third day of admission, he suddenly deteriorated with hypoxia and confusion. He developed acute renal failure, deranged liver function tests and coagulopathy. He had a rapid drop in haemoglobin and platelets. He was admitted to the intensive care where an exchange transfusion was performed. MRI brain showed numerous microhaemorrhages. An MRI of his lumbosacral region showed extensive bone marrow change in keeping with the suspected diagnosis. He had a stormy few days on ITU but slowly improved and was discharged from hospital alive but with subtle cognitive issues. Results: Fat embolism is an under-recognised phenomenon associated with major morbidity and mortality in sickle cell disease. The presentation may mimic a thromboembolic complication but is often characterized by a combination of venous and arterial infarction. It has a characteristic radiological appearance when involving the brain. Pancytopenia with high numbers of nucleated red cells is typical. LDH is often very high. Summary/Conclusions: A high index of suspicion is required to make the diagnosis of fat embolism syndrome ante-mortem. In case reviews, a survival advantage has been reported in patients managed with exchange transfusions although this has not been verified by prospective studies.</span> </span>