B. Acute lymphoblastic leukaemia – Explanation
Acute lymphoblastic leukaemia (ALL)
Aetiology
Most cases of acute leukaemia arise with no apparent cause. There areseveral well
known associations with the development of acute leukaemiathat are sometimes
present. These include radiation exposure,chemotherapeutic agents, as well as some
retroviruses.
Clinical Presentation
The most common presentation results from the effects of the leukaemicblast cells
crowding out the normal marrow cells, resulting in symptoms ofpancytopenia even if the
total white blood cell count is normal.
• Fatigue from anaemia is the most common presenting complaint.
• Bleeding, petechiae, purpura or ecchymoses (due tothrombocytopenia)
•Recurrent and severe infections (oral, throat, skin, perianalinfections commonly). This
is because of the underproduction orabnormal function of white blood cells.
• Left upper quadrant fullness and early satiety due to splenomegaly(10-20%)
Acute lymphocytic leukaemia (ALL) is more common in children, and
acutemyelogenous leukaemia (AML) is more common in adults, but they
areindistinguishable clinically. This means you cannot determine the diagnosisonly from
the clinical presentation.
ALL is more often associated with infiltration of other organs, but AML cando it as well.
Enlargement of the liver, spleen, and lymph nodes and bonepain are common at
presentation.
Diagnosis
The FBC is the first clue to the diagnosis. Depression of all three cell lines is
common at presentation.
FBC
• Anaemia is usual and Hb may be below 5 g/L
• The white cell count can be low, normal, or elevated
• Thrombocytopenia
Many other disorders can present as pancytopenia similar to leukaemiasuch as aplastic
anaemia, infections involving the marrow, metastaticcancer involving the marrow,
vitamin B12 deficiency, SLE, hypersplenism,and myelofibrosis. However, none of these
will have leukaemic blastscirculating in the peripheral blood.Although pancytopenia can
cause all ofthe above, in PLAB, when pancytopenia is in the options, it is
usuallyleukaemia, or aplastic anaemia.
A bone marrow biopsy showing numerous blasts confirms the diagnosis ofacute
leukaemia.
It is very unlikely that the PLAB questions would ask you to differentiate theAML from
ALL using specific test. However, if a child (young age) is givenwith signs and
symptoms of pancytopenia, ALL would be the most likely asit is the commonest
childhood leukaemia.
Note:
• ALL is the commonest childhood leukaemia. Peak age is 2–4 yearsold.
•The Philadelphia chromosome occurs in 15–30% (mostly adults) andis associated
with a poor prognosis.
LEUKAEMIA COMPARISONS
ACUTE LEUKEMIAS
| Acute Lymphoblastic Leukaemia (ALL) | Acute Myeloid Leukaemia (AML) |
|---|---|
Acute lymphocytic leukaemia (ALL) is In the exam, when pancytopenia is in the |
FBC: Auer rods |
CHRONIC LEUKAEMIAS
| Chronic Lymphocytic Leukaemia (CLL)1 | Chronic Myeloid Leukaemia (CML) |
|---|---|
| CLL can often present as an asymptomatic elevation of white cells found on routine evaluation of patients during investigations for other health problems. These patients are exclusively older (majority over 50 years old)When patients do have signs and symptoms they are usually non-specific When should you suspect CLL? When an older patient has marked elevation in white cell count with marked lymphocytic predominance. |
Mnemonic: CML – Crazy Massive Large Spleen
Usually presents at age 40 to 50 years old
The characteristic feature in CML is the |
