Haem/Onc Flashcards
Think generally of differenicals for the presentation of anaemia and pallor
again think generally about a presentation of a child with Anaemia and pallor.
What do you want to cover in:
History
Examination
What investigations do you want to order (and why?)
note: ZN protoporphyrin is high as haem binds to zinc in absence of iron
What is sickle cell disease?
- Autosomal recessive. mutation on chromosome 11 - single amino acid substitution (glutamine for valine).
- causes synthesis of an abnormal B globin chain termed HbS instead of HbA
What is most severe form of sickle cell?
Most severe form homozygous sickle Hb HbSS - sickle cell anaemia
Heterozygotes HbAS have sickle cell trait - protects from falciparum malaria - but can get symptomatic sickling if hypoxic
Some patients inherit one HbS and another abnormal haemoglobin (HbC) resulting in a milder form of sickle cell disease (HbSC)
Note; normal haemolgobin is HbAA
Prevalance of sickle cell disease
Around 10% of UK Afro-Caribbean’s are carriers of HbS (i.e. heterozygous). Such people are only symptomatic if severely hypoxic.
1:700 people of african descent
When do symptoms in (homozyous) sickle cell children start to develop and why?
Symptoms develop until 4-6 months when the abnormal HbSS molecules take over from fetal haemoglobin.
most common time to present in childhood is 3months - 6 years
Pathophysiology of sick cell disease
I.E. what happens to cells when 02 is reduced in the bloodstream
- In the deoxygenated state the HbS molecules polymerise and cause RBCs to sickle
HbAS patients sickle at p02 2.5 - 4 kPa
HbSS patients at p02 5 - 6 kPa - Disease from vaso-occlusive crisis/disease (VOD) and haemolysis. ↑ blood viscosity and low flow in small vessels → block and cause infarction. Premature destruction of RBCs → haemolytic anaemia.
What are risks / complications for children with sickle cell disease
young children
older children
young children
* risk of pneumococcla sepsis greatest <3 years
* Infection from encapsulated organisms (if not vaccinated or no phenoxymethylpenicillin prophylaxis)
* parvovirus - aplastic anaemia
* VOD (vaso-occlusive crises) in long bones,
* sleep related Upper airway obstruction due to adenotonisllar hypertrophy -get hypoxia at night - crisis ask about snoring
* stroke
Older children:
* VOD
* avascular necrosis
* stroke.
Give examples of sickle cell crises and problems
- Vasocclusiove crises- dactylitis (trigger: cold, dehyrdation infection etc)
- acute chest syndrome - chest infection precipitates
- sequestration
- stroke
- infections
- aplastic crises - parvovirus B19
- Priapism
- avascular necrosis - e.g. hip, humerus
- renla impairment
- retinopathyy
- ENT- enlarged adenoids/tonsils obstruction
- leg ulcers
- growth and development delay - final height normal
Why is it important to ensure vaccinations are up to date in a child with sickle cell? what prophylaxis is given?
- patients are functionally hyposplenic by 1year
- high risk of infection from Pneumococcus, Meningococcus, and H. influenzae (HiB).
- Ensure vaccination is up-to-date, and give phenoxymethylpenicillin prophylaxis.
How is Sickle cell disease diagnosed?
Clinical suspicion:
* required in unscreened population.
* Routine screening of Afro-Caribbean children prior to anaesthesia.
Haematology:
* Hb 5–9g/dL, reticulocytes ↑, sickle cells on blood film.
* Hb electrophoresis [high-performance liquid chromatography (HPLC)] is definitive test.
Prenatal:
* on fetal RBCs/fibroblasts or newborn screening (UK).
Investigations in acute crises of sickle cell disease?
Lab:
* FBC - Hb low, reticulocytes raised
* blood culture
* U&E
* creatininie
* CRP - raised in sickling / infection
* Group and save
Imaging:
* CXR (i.e. acute chest syndrom)
Management of acute crises of sickle cell?
- Fluids: aim for 150% normal maintenance (PO or IV).
- Analgesia: titrate to severity often opiates if required.
- Antibiotics: broad-spectrum cephalosporin, after blood culture if fever >38°C. Add a macrolide if atypical pneumonia.
- O 2 :to maintain SpO2 >95%. Keep warm.
- Blood transfusion: for aplastic crisis, sequestration, or anaemia;
- Exchange Transfusion: for sequestration, chest syndrome, or stroke.
Maintenacne / Long term management for sickle cell ?
- Avoid precipitators: hypoxia (air travel), cold, dehydration.
- Vaccinations
- Lifetime PO phenoxymethylpenicillin prophylaxis and daily PO folic acid.
- hydroxyurea: may reduce crises and need for blood.
NOTE : Bone Marrow Transplant: if successful, is curative
A blood film is shown to you with leucoystosis, what is a cause of this?
Leukaemia: e.g. Acute lymphoblastic leukaemia
This is the commonest malignancy in childhood.
What is leukaemia?
Leukaemia is a cancer of immature white blood cells and is the most common type of cancer in children
Leukaemia involves abnormal proliferation and differentiation of leucocytes or their precursor cells.
Most cases of leukaemia are caused by de novo mutations (new mutations which are not inherited). However, there are also genetic syndromes which predispose children to leukaemia.1
Haematopoiesis and development of Leukaemia
explain categories of :
1. acute and chronic leukaemia
2. lymphoid and myeloid leukaemia
Based on where cells originate from and how differenicated the cells are.
Acute: failure of lymphoid or myeloid progenitor cells to differentiate ( lots of very immature cells blast cells)
Chronic: proliferation of cells at a later stage of proliferation
Lymphoid: originated from lymphoid precursors (right side)
Myeloid: myeloid originated from myeloid progenitor
What are the different types of leukaemia?
The types of leukaemia that affect children from most to least common are:
- Acute lymphoblastic leukaemia (ALL) is the most common in children (80%)
- Acute myeloid leukaemia (AML) is the next most common
- Chronic myeloid leukaemia (CML) is rare
Not incl: chronic lymphocytic leukaemia (CLL) v.v.v rare in children.
Explain pathophysiology of leukaemia
Leukaemia is a form of cancer of the cells in the bone marrow. A genetic mutation in one of the precursor cells in the bone marrow leads to excessive production of a single type of abnormal white blood cell.
How does Leukaemia lead to pancytopenia?
The excessive production of a single type of cell can lead to suppression of the other cell lines, causing underproduction of other cell types.
pancytopenia= combination of low:
- Red blood cells (anaemia),
- White blood cells (leukopenia)
- Platelets (thrombocytopenia)
What is the specific problem / fault in Acute lymphoblastic leukaemia (ALL)?
ALL develops as a result of abnormal proliferation and failed differentiation of B or T lymphoid progenitor cells.
Uncontrolled proliferation of these immature lymphocytes (lymphoblasts) within bone marrow prevents normal haematopoiesis, and the abnormal blasts can spread to infiltrate other organs.
What are some RF for Leukaemia?
Genetic syndromes:
- Down’s syndrome: patients are 30 times more likely to develop ALL, and 150 times more likely to develop AML. The characteristic leukaemia seen in Down’s syndrome is M7 acute megakaryoblastic AML.
- Fanconi anaemia
- Li Fraumeni syndrome
- Ataxia telangiectasia
- Nijmegen breakage syndrome
Other risk factors include:
- Exposure to ionising radiation
- Pesticides
- Viruses such as Epstein-Barr virus (EBV), human immunodeficiency virus (HIV)
Typical symptoms of leukaemia?
Non specific - days - weeks
Fatigue and malaise
Unexplained fever
Failure to thrive
Weight loss
Night sweats
Bone and joint pain: particularly affecting the legs
Dyspnoea: caused by anaemia, mediastinal mass or infection
Dizziness and palpitations
Recurrent and/or severe infections
Fevers
Thrombocytopenia: bleeding tendency (epistaxis, bleeding gums), easy bruising, rashes
Clinical examination
Clinical signs of Leukaemia?
- Weight loss
- Skin: pallor, petechial rash, bruising
- Cardiovascular: tachycardia, flow murmur
- Abdomen: distension, hepatomegaly and/or splenomegaly
- Lymphadenopathy
- testicular swelling
NICE:
red flag clinical SIGNS suggestive of haematological malignancy in children.
An urgent specialist assessment is required if any of the following red flag features are present:
- Unexplained petechiae
- Unexplained hepatosplenomegaly
NICE:
red flag clinical features suggestive of haematological malignancy in children.
An urgent full blood count is required if any of the following red flag features are present:
- Pallor
- Persistent fatigue
- Unexplained fever
- Unexplained persistent infection
- Generalised lymphadenopathy
- Unexplained bruising or bleeding
- Persistent/unexplained bone pain
How does Acute lymphoblastic leukaemia (ALL) tend to present (PASSMED)
Features - those predictable by bone marrow failure:
Features may be divided into those predictable by bone marrow failure:
* anaemia: lethargy and pallor
* neutropaenia: frequent or severe infections
* thrombocytopenia: easy bruising, petechiae
And other features:
* bone pain (secondary to bone marrow infiltration)
* splenomegaly
* hepatomegaly
* fever is present in up to 50% of new cases (representing infection or constitutional symptom)
* testicular swelling
What are differencial diagnoses for leukaemia?
Infective, malignant, autoimmune. haematological
Bedside investigations for leukamia?
- Observations: fever can indicate malignancy or infection, and tachycardia can occur in infection or anaemia.
- Urine dip: infection is an important differential diagnosis.
- ECG: may show tachycardia, and a baseline is useful before cardiotoxic chemotherapy.
Tests for Leukaemia?
all: bloods, marrow, CSF, cytogenic anyalysis, imaging
Bloods:
* WCC (up but can be normal)
* Normochromic normocytic anaemia + LOW Platelets
* high urate
* high LDH
Marrow:
* 50-98% nucleated cells will be blasts
CSF
* Pleocytosis with blast forms
* protein high
* glucose low
Cytogenic:
* 80% have genetic abndormalities
Imagine:
* CXR - may be mediastinal lymphadenopathy
Ox handbook specialities p 242
Leukaemia lab investigations :
What looking for in FBC?
- Blast cell proliferation causes raised white blood cell count
- pancytopenia will occur with bone marrow suppression (anaemia and thrombocytopenia are common, while white blood cell count may be variable).
Leukaemia lab investigations :
What looking for on Blood film?
Blood film:
- shows the presence of blast cells (there may be a false negative if blasts are confined to bone marrow).
- Blast cells should normally not be seen in peripheral blood- HIGHLY suspicious for leukaemia if seen on microscopy.
Leukaemia lab investigations :
What looking for on coag profile?
- may be deranged
- may show disseminated intravascular coagulation
Leukaemia lab investigations :
What looking for on kidney and liver function?
- baseline prior to starting chemotherapy.
- Liver tests - may indicate liver infiltration
- Electrolytes can show complications of very high cell turnover such as tumour lysis syndrome (although this is usually seen post-chemotherapy).
Leukaemia lab investigations :
What looking for with lactate dehyrogenase and uric acid?
- Raised lactate dehydrogenase and uric acid: occur with increased cell turnover.
Leukaemia lab investigations :
What looking for with blood cultures?
if presenting with fever/signs of infection
Leukaemia imaging investigations : what and why?
Chest X-ray:
* identify early if a mediastinal mass is present before the child receives any anaesthetic.
* mediastinal mass may be present in T-cell lymphoblastic lymphoma, which overlaps with T-cell ALL, and can cause airway compromise, cardiovascular collapse, and death.
* An X-ray may also show infection, enlarged nodes, and lytic bone lesions.
Echocardiogram:
* prior to starting cardiotoxic chemotherapies.
What are bone marrow aspirations used for in leukaemia care?
- Diagnosis (presence of ≥20% blasts)
- Minimal residual disease analysis after treatment
- Cytogenetics: detects chromosomal aberrations
- Immunophenotyping: uses flow cytometry analysis to characterise the leukaemia blasts
- cytogenetics / immunophenotyping- for disease classification and risk stratification to guide treatment.
Note:
* A trephine biopsy also sometimes done with a second needle, removes a small piece of bone with the marrow inside - looked at under microscope
* LP sometimes done looking for the presence of leukaemic cells in cerebrospinal fluid.
What is minimal residual disease?
At the end of induction chemotherapy, the blast cell count should be ≤5% for patients to be classed as being in remission.
Presence of residual disease (i.e. persistent leukaemic cells) indicates the need for more intensive chemotherapy.
What are the 2 most widely known classifcation systems for leukaemia?
- French-American-British (FAB) classification is based on morphology (the appearance of cells under a microscope) and cytochemical staining of leukaemic cells.
- World Health Organisation (WHO) classification system uses cytogenetics (chromosomal analysis) and immunophenotyping (use of antibodies to detect white blood cell antigens).
how is leukaemia managed?
Chemotherapy is the mainstay of treatment in leukaemia.
Acute lymphocytic leukaemia
stages of chemo
- Induction: intensive 4-6 weeks aims to destroy all leukaemic blast cells. To reduce the risk of tumour lysis syndrome, pre-phase treatment with hydration and allopurinol/rasburicase is given prior to chemotherapy.
- Consolidation and CNS treatment: aim to maintain remission. LP with intrathecal methotrexate aims to prevent spread to the CNS.
- Delayed intensification: aim to remove as many remaining blasts as possible prior to the maintenance phase.
- Maintenance: treatment continues for 2 years in girls, and 3 years in boys. This can involve oral or intravenous chemotherapy, steroids, and intrathecal treatments
What chemo agents used in treating acute lymphocytic leukaemia?
Chemotherapy agents commonly used include:
corticosteroids, vincristine, anthracyclines, asparaginase, cyclophosphamide and cytarabine.
What are the stage of treatment for acute myeloid leukaemia?
- Induction: intensive phase which aims to destroy all leukaemic cells.
- Post-remission treatment: usually involves two further courses of chemotherapy, aiming to destroy residual cells and prevent a recurrence.
Bone marrow tests are repeated following induction, to assess whether remission has been achieved.
What are some other treatements for leukaemia?
- Bone marrow transplant: this is only used in patients with a high risk of disease recurrence, or with recurrence following standard chemotherapy.
- Testicular radiotherapy: used for patients with testicular infiltration.
- CNS treatments: chemotherapy drugs may be injected intrathecally (via lumbar puncture), and occasionally radiotherapy is used for infiltration following relapse.
Supportive measures for leukaemia treatment?
- Education for families
- Broad-spectrum antibiotics urgently for children (suspect neutropenic sepsis).
- Prophylactic antimicrobials: particularly co-trimoxazole (to prevent pneumocystis jirovecii) in ALL, and antifungals in AML.
- Blood transfusions.
- Allopurinol (prevention of tumour lysis syndrome).
- Insertion of a central venous catheter for chemotherapy and blood sampling.
- Granulocyte-colony stimulating factor (G-CSF): to support cell counts (e.g. prolonged neutropenia).
- Psychosocial support, educational support, advice about financial support for families
What are some early complications of leukaemia?
- Neutropenic sepsis
- Thrombocytopenia: bleeding, stroke, haemorrhage (lung or gastrointestinal)
- Blast cell lysis
- Leucostasis: stroke, pulmonary oedema, heart failure
- CNS infiltration: seizures, stroke
What are some therapy - related complications of leukaemia?
- Corticosteroid side effects: behavioural issues, weight gain
- Neutropenic sepsis
- Tumour lysis syndrome
- Mucositis, gastrointestinal inflammation
- Renal and hepatic toxicity
- Neurotoxicity
- Venous thromboembolism
- Alopecia