Mast cell leukaemia is an extremely aggressive subtype of acute myeloid leukaemia that usually occurs de novo but can, rarely, evolve from transformation of chronic myeloid leukaemia into the more aggressive acute myeloid leukaemia.

WHO criteria

• Prevalence of 20% neoplastic mast cells in marrow and 10% in blood.
• “Aleukemic” mast cell leukaemia: Mast cells represent < 10% of blood cells

---

Clinical features

Rapidly progressive disorder with leukemic mast cells in blood and in large numbers in marrow.

• Common signs and symptoms:
  • Fever, headache, flushing of face and trunk
• Typical cutaneous mast cell infiltrates of urticaria pigmentosa are usually not present before, during, or after diagnosis in patients who have mast cell leukemia.
• Histamine release from neoplastic mast cells:
  • Abdominal pain, bone pain, and peptic ulcer
    • More prevalent than in other subtypes of AML
• Hepatosplenomegaly (characteristic)
• Severe haemorrhage:
  • Due to Mast cells anticoagulant release (eg. heparin) & liver and splenic dysfunction
• Bone involvement:
  • Osteoporosis

---

Diagnosis

Imaging

Abdominal ultrasound or computerized tomography (CT) scanning

• Hepatosplenomegaly and lymphadenopathy

Plain radiography and bone densitometry

• Assess bone involvement and the presence of osteoporosis

Investigations

Peripheral blood smear

Endoscopy and biopsy

• Suspected gut involvement

---

Managment

• Immunotherapy:
  • Anti-IgE immunoglobulin
• Chemotherapy:
  • Combination of: Cytosine arabinoside + idarubicin/daunomycin/mitoxantrone (as for acute myeloid leukaemia)
• Stem cell transplantation