ACUTE MYELOID LEUKAEMIA

ACUTE MYELOID LEUKAEMIA is a malignant tumour of haemopoietic precursor cells of non-lymphoid lineage, almost certainly arising in the bone marrow. 

Incidence

1 in 50,000 annually.  Increasing frequency with age (median 60 years).  Cause unclear – association with heavy radiation dose exposure eg. post-Chernobyl disaster, chronic benzene exposure, alkylating agents and hereditary predisposition in Down’s and Fanconi’s syndromes, pre-existing myeloproliferative disorders.

Classification – morphological (French-American-British, FAB)

M0 - Undifferentiated

            M1 - Early myeloblastic (minimal differentiation)

            M2 - late myeloblastic (differentiation)

            M3 - promyelocytic

            M4 - myelomonocytic

            M5 - monoblastic

            M6 - erythroleukaemic

            M7 – megakaryoblastic

·         Immunophenotyping useful in diagnosis of M0, 4, 5, 6 and 7

·         Cytogenetics important in detecting translocations and deletions

-          t(15;17) in M3

-          t(8;21) in M2

-          inv (16) in M4Eo, are all associated with better prognosis

-          monosomy 7 and multiple breakages are poor prognosis

Clinical features

·         Acute presentation common; often critically ill.

·         Common symptoms include malaise, sweats, anaemic symptoms (breathlessness, faintness and palpitations)

·         Infections – particularly chest, mouth, perianal, skin (Staph.pseudomonas, HSV, Candida).

·         Bleeding, purpura, menorrhagia and bleeding nose, gums, rectal, retina (especially M3-DIC) and gum and skin infiltration (M4,M5).

·         Leucostatic signs of hypoxia, retinal haemorrhage or diffuse pulmonary shadowing.

Investigations and diagnosis

·         FBC and blood film.

·         Bone marrow and biopsy.

·         Total WBC usually ­­ with blast cells on film – but may be low.

·         Hb. and Plts usually ¯.

·         Marrow heavily infiltrated with blasts 9>30%) – immunophenotyping and karyotyping on blood and marrow allows classification as above.

Emergency treatment

·         Seek expert help immediately

·         Cardiovascular and respiratory resuscitation may be needed in septic shock of massive haemorrhage.

·         Leucapheresis if peripheral blast count high or signs of leucostasis (retinal haemorrhage, reduced conscious level, diffuse pulmonary shadowing on CXR or hypoxia)

Supportive treatment

·         Give explanation and offer counselling.

·         RBC and platelet transfusion support will continue through treatment.

·         Start neutropenic regimen as prophylaxis.

·         Start hydration and allopurinol PO.

Specific treatment

Discuss with haematologist.