🧬 Leukaemia is a malignant disorder of the blood and bone marrow characterised by uncontrolled proliferation of abnormal white blood cells. This disrupts normal haematopoiesis → causing anaemia, bleeding, and infection. Different types of leukaemia vary in onset, severity, and prognosis, but all require timely recognition and treatment.

📖 Classification of Leukaemia

Acute Leukaemia ⚡: Rapid progression, accumulation of immature "blast" cells. Requires urgent treatment.
Chronic Leukaemia 🐢: Slower progression, abnormal but more mature cells, often discovered incidentally.
Myeloid Leukaemia 🩸: Involves granulocytes, RBCs, or platelets derived from myeloid stem cells.
Lymphocytic Leukaemia 🛡️: Involves lymphocytes (B, T, NK cells) derived from lymphoid stem cells.

🔬 Myeloid vs Lymphoid Lineage

Lymphoid stem cell: B cells, T cells, NK cells
Myeloid stem cell: RBCs, Platelets, Neutrophils, Monocytes, Eosinophils, Basophils

🧾 Types of Leukaemia

Acute Lymphoblastic Leukaemia (ALL) 👶 – Most common in children, but also seen in adults.
Acute Myeloid Leukaemia (AML) 🧓 – More common in adults, rapid onset, associated with myeloid blasts.
Chronic Lymphocytic Leukaemia (CLL) 👴 – Commonest adult leukaemia in the West, slow progression.
Chronic Myeloid Leukaemia (CML) 📉 – Driven by the Philadelphia chromosome (BCR-ABL), progresses through chronic → accelerated → blast crisis phases.

📊 Incidence and Notes

Type	Incidence	Notes
ALL 👶	~9%	Most common childhood leukaemia; rapid progression if untreated.
CML 📉	~10%	Adults; linked to Philadelphia chromosome; average age ~64 yrs.
CLL 👴	~23%	Slow buildup of abnormal B cells; commonest leukaemia in elderly.
AML 🧓	~27%	Bone marrow packed with myeloid blasts; most cases >50 yrs.
Myeloproliferative Disorders 🔄	~31%	Include polycythaemia vera, myelofibrosis, essential thrombocythaemia.

⚠️ Signs & Symptoms

Fatigue, weakness, pallor (anaemia) 😴
Frequent or severe infections 🤒
Easy bruising, bleeding, petechiae 🩸
Unexplained weight loss ⚖️
Bone or joint pain 🦴
Swollen lymph nodes or splenomegaly 🫁

🧪 Diagnosis

Blood tests: Abnormal WBC, anaemia, thrombocytopenia.
Bone marrow aspiration/biopsy: Confirms leukaemic blasts.
Flow cytometry: Immunophenotyping to classify lineage.
Genetic tests: e.g. BCR-ABL in CML, FLT3 in AML.
Imaging: CT/ultrasound for lymphadenopathy or organomegaly.

📚 High-Yield Revision Summary

Category	Key Facts
🔬 Definition	Malignant proliferation of abnormal WBCs in bone marrow → disrupts normal haematopoiesis (anaemia, infection, bleeding).
📖 Classification	Acute: Rapid, immature "blasts". Chronic: Slow, more mature cells. Myeloid: Affects granulocytes, RBCs, platelets. Lymphoid: Affects lymphocytes (B/T/NK).
🧾 Common Types	ALL: Children, rapid, good prognosis with treatment. AML: Adults >50, rapid, poorer prognosis. CLL: Elderly, slow, commonest adult leukaemia. CML: Middle-aged, BCR-ABL (“Philadelphia chromosome”), treat with TKIs.
⚠️ Symptoms	Fatigue, pallor (anaemia) Infections, fever (neutropenia) Easy bruising, bleeding (thrombocytopenia) Lymphadenopathy, splenomegaly
🧪 Key Investigations	Blood film: blasts or abnormal WBCs Bone marrow biopsy: diagnostic Flow cytometry: lineage Genetics: BCR-ABL (CML), FLT3 (AML)
💊 Management	Chemotherapy: Mainstay in acute leukaemias. Targeted therapy: TKIs (CML), ATRA (APL). Immunotherapy: CAR-T, monoclonal antibodies. Stem cell transplant: Curative option in selected cases. Supportive care: Transfusions, antibiotics, growth factors.
📈 Prognosis	ALL (children): Cure rates >80% 🎉 CML: Excellent with TKIs, near-normal lifespan. AML: Poorer prognosis, especially in elderly. CLL: Often indolent, may not require immediate therapy.

💡 Exam Tip: Think “Anaemia, Infection, Bleeding” as the classic triad of leukaemia presentation. Always mention bone marrow biopsy for diagnosis and TKIs for CML in finals!

💊 Treatment Options

Chemotherapy 💉: First-line for acute leukaemias.
Targeted therapy 🎯: e.g. Imatinib for CML (BCR-ABL tyrosine kinase inhibitor).
Immunotherapy 🛡️: CAR-T therapy, monoclonal antibodies (rituximab in CLL).
Radiotherapy ☢️: For localised disease or CNS prophylaxis.
Stem cell transplant 🌱: Potentially curative in high-risk/relapsed cases.
Supportive care 🤲: Transfusions, antibiotics, growth factors.

📈 Prognosis

Prognosis depends on type, age, and cytogenetics. ✅ Childhood ALL – cure rates >80%. ✅ CML – near-normal life expectancy with tyrosine kinase inhibitors. ⚠️ AML in elderly – poorer prognosis, but improving with novel therapies. Overall, advances in precision medicine and stem cell transplantation continue to improve survival outcomes.

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Leukaemia