Leukemia: Etiology, Classification and its Investigation

 Leukemia: Etiology, Classification and its Investigation



In general term it is also called as blood cancer cancer of blood forming tissue bone marrow and lymphatic system. Abnormal or neoplastic proliferation of white blood cells lymphoid or myeloid is termed as leukemia full stop the cell are immature and usually begin in bone marrow the immature cell are called as blast cells or leukemic Cell full stop B cells multiply rapidly and accumulate in bone marrow replacing normal cells does result in bone marrow failure producing symptoms like anemia average infections fever extra prevalence of leukemia is more in men than women.


○ Etiology / risk factors

1.Exact cause of leukemia is unknown

2.Genetic and environmental factors play a major role

3.Heredity family history is evident

4.Infections certain viral infections are involved in development of leukemia-

a.  HTLV-I-  t cell lymphoma leukemia

b.  Epstein Barr virus - acute leukemia, Hodgkin's disease

c.  HTLV-II- hairy cell leukemia

d.  Hepatitis C virus (HCV)- lymphoplasm acytic lymphoma.

e. Helicobacter pylori- bacterial infection of gastric mucosa. 


○ Environmental factors

a.  Radiations- occupational radiation exposure, patient receiving Radiation therapy, atomic bomb explosions.

b.  Chemical carcinogens- hair dyes, agricultural Chemicals, tobacco chewing, smoking, benzene etc.

c. Drugs-  Phenytoin,   chemotherapeutic drugs.


○ Disease affecting immunity-

a. Immunodeficiency disorders like AIDS

b. Autoimmune disease like rheumatoid arthritis, SLE, Sjorgen's syndrome, sprue.

c.  down syndrome.


○ Classification 



# Based on the type of cell predominantly involved-

1.  Myeloid

2. Lymphoid

 

# On the basis of history of disease

1. Acute

2. Chronic


# Combination of both four common type

○ Acute myeloid leukemia

○ Acute lymphoid leukemia

○ Chronic myeloid leukemia

○ Chronic lymphoid leukemia


# Acute leukemia

○ Rapid increase in number of immature blood cells so the disease worsen quickly.

○ These are more common in children and young ones

It is divided into 2 types-

* Acute lymphoid 

*Acute myeloid

 Acute lymphoid leukemia is common in young children

Acute myeloid leukemia is common in adults and all ages


○ Clinical features

SYMPTOMS OF BOTH MYELOID AND LYMPHOID LUKEMIA



Acute myeloid and acute lymphoid leukemia have almost same clinical features

○ Progress rapidly in few days to months

○ Anemia- Pallor, easy fatigability, dyspnea, malaise.

○ Thrombocytopenia- bleeding, purpura, petechie, easy fatigability, gum bleeding, epistaxis, Melaena. 

○ Granulocytopenia- susceptible to infections of skin, lungs, urinary tract, perianal region, gums.

○ Gum hypertrophy

○ Hepatomegaly

○ Splenomegaly

○ Lymphadenopathy

○ Pain in bones

○ Abdominal pain

○ Fever, weight loss

According to FAB classification, leukemia is said to be acute if bone marrow consists of more than 30% blasts. FAB has classified acute myeloid leukemia into 8 subtype on the basis of morphology and cytochemistry (M0-M7).

FAB  has classified acute lymphoid leukemia into three types (L1-L3) on the basis of morphology and cytochemistry.


○ Investigation  of acute leukemia

#  CBC 

#  Peripheral blood smear

#  X ray chest mediastinal mass is seen in acute lymphoid leukemia

#  Bone marrow aspiration

# Liver function test, renal function test, serum electrolytes.

# Total WBC count may increase over lakh/mm

# Hemoglobin and platelet counts decreases

# Serum lactate dehydrogenase (LDH)-elevated

# Elevated uric acid and Alkaline phosphatase

#  Coagulation test- DIC-disseminated intravascular coagulation

#  CSF examination


# Chronic leukemia

*Mostly occur in elderly people

*It takes month or years to progress

*Chronic lymphocytic leukemia occurs in elderly while chronic myeloid leukemia is seen in middle aged people.

* large number of abnormal WBCS are present.


○ It is divided into two types

1. Chronic lymphoid on lymphocytic lymphoblastic leukemia-

a.  Features of anemia, weakness, fatigue, dyspnea. 

b.  Lymph node enlargement

c.  Splenomegaly

d.  Susceptibility to infections

e.  Bone and joint pain

f.  Tonsillar enlargement

g.  Mediastinal pressure


○ Investigation of chronic lymphocytic leukemia

1. CBC

*Anemia

* WBC count Magda Leukocytosis (50,000 to 2lakh/lit).

*Platelet counts-normal are moderately low

2. Bone marrow examination

* lymph node biopsy


2. Chronic myeloid leukemia

○ both sex equally affected

○ occur is in third or fourth decade of life.

○ insidious onset


# Clinical features

1. Anemia- weakness, pallor, dyspnea, tachycardia.

2. Weight loss, anorexia, latitude, night sweat. 

3. Splenomegaly

4. Bleeding tendencies, epistaxis, hematomas, menorrhagia.

5. Gout, visual disturbances.

  

○ Investigations of chronic myeloid leukemia

1. Anemia

2. WBC count- marked leukocytosis 2lakh or more count. 

3. Platelet count normal or raised

4.  Bone marrow examination

5. Elevated serum B12 and Vitamin B12 binding capacity

6. Elevated serum uric acid.


○ Hairy cell leukemia (HCL)

* It is an uncommon and unusual type of b-cell malignancy

* There is presence of hair cells in the blood and bone marrow

* Splenomegaly

* Common in elderly males

* Susceptible to infections

* Infiltrates- bone marrow, liver, spleen.

 

○ Investigation

* Pancytopenia

* presence of hair cells in blood and bone marrow.

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