diagnostic features
Last reviewed 01/2018
- peripheral blood
- pancytopenia with circulating blasts is characteristic
- WBC - normal or raised; 50% of individuals have count less than 10 x 10^9/l; 20% have count greater than 100 x 10^9 /l; usually a preponderance of blasts but 10% have aleukaemic leukaemia - blasts absent from peripheral blood although still present in marrow
- red cells - anaemia - usually normocytic but may be macrocytic; progressive, may become severe
- platelets - usually reduced
- bone marrow - hypercellular; diagnosis is made on having more than 30% blasts in the marrow
- CSF - blasts present in meningeal leukaemia
- CXR - often mediastinal mass in ALL especially T cell
- blood cultures - always if patient is febrile
- coagulation studies - DIC indicated by reduced fibrinogen, increased prothrombin time, presence of fibrin degradation products
- hyperuricaemia and hypokalaemia often seen
- important to distinguish between AML and ALL:
- morphological - Auer rods pathognomonic of AML
- histochemical 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