Leukemia

Leukemia, also referred to as leucosis in animals, is a malignant disease of the hematopoietic system. It is associated with uncontrolled proliferation and accumulation of abnormal white blood cells (leukocytes) in the bone marrow.

The pathological process begins in the bone marrow, where a single hematopoietic cell undergoes mutation and gives rise to a malignant clone. These leukemic cells gradually displace and suppress normal hematopoietic stem cell, leading to anemia, bleeding, and severe infections.

Classification and Pathophysiology

Leukemias are classified according to two main criteria: disease course (acute or chronic) and the type of affected cells (lymphoblastic or myeloblastic). Based on this differentiation, there are four major disease groups:

• Acute lymphoblastic leukaemia (ALL). Most common in children.
• Acute myeloblastic leukaemia (AML). The most frequent acute leukemia in adults.
• Chronic lymphocytic leukemia (CLL). Typically seen in older adults.
• Chronic myeloid leukemia (CML).

In acute leukemias, immature cells (blasts) proliferate in the bone marrow, and the disease progresses rapidly. In chronic leukemias, the malignant cells are more differentiated, and the disease course is slower, often asymptomatic in the early stages.

Clinical Significance

The clinical manifestations of leukemia are associated with suppression of normal hematopoiesis. Symptoms are often nonspecific and may include fatigue and pallor (due to anemia), frequent infections (due to leukocyte deficiency), bleeding gums, easy bruising, and nosebleeds (due to thrombocytopenia). Bone pain, lymphadenopathy, and splenomegaly may also be reported.

Initial evaluation begins with a complete blood count (CBC), which reveals typical abnormalities. Bone marrow examination is essential for establishing a definitive diagnosis and identifying the leukemia subtype. This may involve either sternal bone marrow aspiration or trephine biopsy.

Management depends on the leukemia type, patient age, and other individual factors. Treatment options may include chemotherapy, targeted therapy, immunotherapy, and hematopoietic stem cell transplantation.