RxPG - Differentiating features of Leukemias (Leukaemias)

I. Acute Leukaemias
-----------------------------------------------------------

A. Lymphoblastic:
---------------------
-Accounts for 20% of all acute leukaemias.
-Accounts for 80% of childhood leukaemia.
-Peak incidence at age 4 years.

Most patients present with an acute illness of several days or less frequently, with tiredness or non-specific aches over several weeks or months.

-Clinical features can be grouped into:

1. Consequences of bone marrow failure - anaemia, bleeding, vulnerability to infection.
2. Consequences of accumulation of leukaemic cells.

Important Points to remember:

-The patient with acute lymphoblastic leukaemia is usually a child, whereas the patient with acute myeloid leukaemia is rarely a child.

-Although the marrow is usually extensively replaced by leukaemic cells, elated symptoms are uncommon. Rarely there may be bone tenderness in childhood ALL.

-A common presentation of childhood ALL is with joint and muscle pain. ALL does not infiltrate extra-medullary tissues - lymph nodes, spleen, liver, meninges - as much as AML.

-T cell ALL may present with superior vena caval obstruction.

B. Myeloid:
---------------------
-Accounts for 80% of acute leukaemias
-Peak incidence between 15 and 39 years

It is important to distinguish between AML and ALL:

-Morphological - Auer rods pathognomic of AML
-Histo-chemical stains for myeloid enzymes such as peroxidase or chloroacetate confirm AML
surface markers characteristic of primitive lymphoid cells identify ALL, e.g. terminal deoxynucleotide transferase present in 95% of cases of ALL
-Primitive B lymphocyte antigens such as CALLA, B1, BA1 may help to identify ALL
-T cell ALL diagnosed by rosette formation with sheep erythrocytes or identification of cell markers by monoclonal antibodies such as Leu-1 or Leu-9

II. Chronic Leukaemias
------------------------------------------------------

CLL usually has an insidious onset. Approximately 25% of patients are diagnosed incidentally when they are found to have lymphocytosis. Rapidly progressive CLL occurs occasionally and is characterised by larger, less mature - appearing lymphocytes - "prolymphocytic" leukaemia.

Typical clinical features of CLL include:

-Non-specific symptoms - lethargy, weight loss, fever and sweating, and infections.
-Attributable to anaemia and thrombocytopenia - which may be autoimmune.
-Lymphadenopathy - occurs in 80% of cases. Typically, moderate enlargement, affecting nodes in the neck, axilla and groin. Classically, symmetrical with non-tender, rubbery nodes. May have developed over a period of months or years.
-Hepatosplenomegaly - in 50% of cases.
-Skin lesions - pruritus, Herpes zoster, generalised infiltration (l'homme rouge, usually associated with pruritus), vesibullous lesions

The clinical features of chronic myeloid leukaemia may be classified into:

non-specific systemic features:
-anaemia
-malaise & fatigue
-weight loss
-sweating

common features:
-bleeding diathesis
-discrete ecchymoses
-menorrhagia
-splenomegaly
-hepatomegaly

rare features:
-abdominal pain or pleuritic pain due to splenic infarction
-gout
-retinal haemorrhages
-priapism
-fever

comparison of CML and CLL

-lymphadenopathy
CML: uncommon
CLL: common

-hypogammaglobulinaemia
CML: not feature
CLL: may occur

-positive Coomb's test
CML: not feature
CLL: may occur

-development of blast
CML: common
CLL: not common crisis

-prognosis
CML worse than CLL