Page 21 - Delaware Medical Journal - May 2017
P. 21
CASE REPORT
results were consistent with brain death. Gift of Life was contacted for organ donation and after process completed, autopsy conducted at request of patient’s family. Sections of the patient’s lung showed multiple areas of fat emboli of the small vessels. Immunohistochemical staining revealed fat cells within the vessels. These of bony infarction and multiple fat emboli. Neuropathology examination revealed severe diffuse acute neuronal necrosis consistent with severe anoxia and clinical brain death.
DISCUSSION
Fat Emboli Syndrome (FES) is due to the release of fat globules into the venous circulation. It can affect the respiratory, neurological, cutaneous, and hematological systems. Most commonly, FES is seen
in the setting of long bone fractures
and patients who have had orthopedic surgeries. Cases of non-traumatic FES are much rarer and are generally attributed to bone marrow necrosis.
necrosis of myeloid tissue and medullary stroma in areas of the haemopoietic bone marrow. When bone marrow necrosis
is extensive, it results in pancytopenia. Nucleated red blood cells are noted on the peripheral blood smear. There is disruption of the normal architecture of the bone marrow. Most cases of bone marrow necrosis are in the setting of malignancy. Other rarer causes of bone marrow necrosis include autoimmune and infectious causes as well as sickle cell disease.1
marrow necrosis was described in 1941 in a patient who presented with pain and rapidly deteriorated. At the time of her
Fat Emboli Syndrome
is a rare complication
in patients with hemoglobinopathies, more commonly in those with milder forms, such as hemoglobin SC.
presentation, the patient was diagnosed
with sickle cell disease.2 Since then, other cases in patients with sickle cell disease have been noted, with a literature review from 2005 identifying 24 cases.3 A more recent literature review from 2014 provided an overview of 110 cases. In several cases, at time of autopsy. Patients often presented with pain and fevers and then rapidly deteriorated with change in mental status, drop in cell counts, and involvement of other organ systems, most commonly the lungs followed by the kidneys. Patients
with hemoglobin SC disease appear to be at higher risk, possibly due to the higher blood viscosity as compared to patients with sickle cell disease. The milder the disease, the higher the risk of FES.1
The diagnosis of Fat Emboli Syndrome
is often missed or only diagnosed post- mortem. In their literature review, Tsitsikas et al noted that more than 50% of cases
are diagnosed at autopsy.1 percentage of sickle cell patients (40.4%, Manci et al4) present with a pain crisis and die suddenly. A study by Graham et al in 2007 noted the presence of fat emboli in the lungs in 1/3 of these sudden deaths.5 There is also evidence of a link between parvovirus B19 and BMN/FES. Tsitsikas et al noted that 24% of the patients with diagnosed BMN/FES had evidence of infection with B19. Other potential triggers
prostaglandin infusion for the purpose of terminating a pregnancy and administration of oxytocin at the time of labor.1
Currently, there are two sets of criteria used to diagnose FES — Gurd’s and Schonfeld’s criteria. With regards to Gurd’s criteria: 1 major and 4 minor criteria are required to make the diagnosis. Major criteria include axillary or subconjunctival petechiae, hypoxemia, CNS depression,
or the presence of pulmonary edema. Minor criteria include heart rate >120, hyperthermia, the presence of fat globules in urine or sputum, thrombocytopenia, decreased hematocrit, or an increased erythrocyte sedimentation rate.6 For Schonfeld’s criteria, a score of 5 or higher is needed to make a diagnosis of FES. Five points are given for the presence of petechiae, four for CXR changes, three for hypoxemia, and one for each of the following: temperature>38 degrees C, heart rate>120, respiratory rate>30, or the presence of altered mental status.7
The pathogenesis of FES is not clear
and more than one mechanism may be responsible. Tsitsikas et al suggest an underlying immunological reaction, in and dysfunction. Another proposed
theory involves mechanical obstruction
by fat emboli causing vaso-occlusion in
the lungs and the formation of cardiac or pulmonary right to left shunts resulting
in occlusion of other vessels such as intracranial vessels. When fat emboli occlude pulmonary vessels, lipase and subsequently free fatty acids are released, leads to direct endothelial damage and respiratory distress. There is also activation of the complement system and thrombi
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