Thank you to those of you who joined in with this case; we hope it was a useful and enjoyable way to learn. We covered a few important topics during the case:
- the differential for a macrocytic anaemia
- Investigating macrocytosis
- Blood film appearances of MDS and AML
- Myelodysplasia, including prognostication
- Presentation of Acute Myeloid Leukaemia
- Neutropenic Sepsis
For exam purposes the differential diagnosis and investigation of anaemia are important. For real life purposes understanding neutropenic sepsis management is crucial so we’ll discuss it a little further.
Neutropenia is defined in different ways, but as a rule of thumb the risk of sepsis rises once the absolute neutrophil count is less than 1. Once the neutrophil count is less than 0.5 the risk of overwhelming sepsis is much more significant.
Neutropenia is most commonly caused by chemotherapy and as such can often be predicted. Chemotherapy patients should always be advised on the symptoms of sepsis and be given emergency contact information in order to allow prompt treatment to be started.
Other causes of neutropenia include:
- Drug induced cytopenias, caused by drugs such as anticonvulsants, some anti-psychotics, anti-inflammatories (DMARDs) and some antibiotics. This may be dose related (such as with methotrexate) or idiosyncratic.
- Myelodysplasia (see previous post)
- Acute Myeloid or Lymphoblastic Leukaemia
- Auto-immune neutropenia
- Cyclical neutropenia
- Felty’s syndrome (neutropenia, splenomegaly and rheumatoid arthritis).
It is worth mentioning that the neutrophil count in patients with Myelodysplasia and leukaemia might be normal, but the function of those neutrophils is not normal and these patients are still at high risk of sepsis.
Management of neutropenic sepsis is straight forward on paper – recognise that the patient is in an ‘at risk’ category, administer broad spectrum antibiotics rapidly (the national target is one hour ‘door to needle’) and assess for sepsis. The key is to understand how rapidly these patients can deteriorate. It is not unusual for chemotherapy patients to deteriorate to the point of requiring ITU admission within a couple of hours of developing a fever. For this reason it is important to take every temperature in these patients seriously.
The other important feature to note is that whilst bacterial sepsis is the most common type of infection experienced by neutropenic patients, fungal infections are an important differential. The longer the duration of neutropenia the more likely fungal infections are to develop and thus are seen in patients requiring prolonged intensive chemotherapy, such as bone marrow transplant patients.
Fungal infections most commonly affect the lungs and can be detected by high resolution CT of the chest. We will generally scan high risk patients if they have had a fever for more than 48-72 hours despite broad spectrum antibiotics, as well as starting anti-fungal therapy. Fungal infections are frequently fatal in patients with prolonged neutropenia, such as those with untreatable leukaemia and myelodysplasia.
- Macrocytic anaemia has many causes and B12/folate deficiency is the most important differential.
- Myelodysplasia is one cause of macrocytic anaemia which should be considered, particularly in older patients, and can often be identified as likely by examination of the blood film.
- Myelodysplasia can be classified using prognostic scores (such as the IPSS and IPSS-R) which helps to counsel the patients. The prognosis for patients with MDS varies from a few months to several years and the scoring system helps to place patients on this spectrum.
- The natural history of MDS is to evolve into Acute Myeloid Leukaemia. The management of AML depends on many features of the patient, including:
- patient age
- patient comorbidities
- cytogenetic results.
- In elderly patients the management of AML is supportive, as the toxicity of chemotherapy would be too great. This must clearly be decided on a case-by-case basis.
Please get in touch with us if you want more information or have any questions. Please continue to follow the #unofficialCSIM2 hashtag and best of luck with your studies.
Guidance on neutropenic sepsis: https://www.nice.org.uk/Guidance/CG151
Student BMJ article on neutropenic sepsis: http://student.bmj.com/student/view-article.html?id=sbmj.d785