Blasts

In pathology, the term “blasts” refers to immature cells that are in the early stages of development into mature cells. These cells are typically found in the bone marrow, where they are part of the normal process of blood cell formation, known as hematopoiesis. Blasts can develop into various types of blood cells, such as red blood cells, white blood cells, and platelets, depending on the specific lineage they belong to. For instance, myeloblasts will mature into white blood cells of the myeloid lineage (like neutrophils and monocytes), while lymphoblasts will develop into lymphocytes, a type of white blood cell involved in the immune response.

Function of blasts

The primary function of blasts is to serve as the precursor cells that will differentiate and mature into various types of specialized blood cells. This process is tightly regulated to maintain a balance between the different types of blood cells needed by the body to function properly. Blasts undergo a series of divisions and differentiation steps under the influence of various growth factors and signals.

Where are blasts normally found?

Blasts are normally found in the bone marrow, which is the soft, spongy tissue inside bones. The bone marrow is the primary site of new blood cell production throughout a person’s life. A small number of these cells are also typically present in the bloodstream; however, they are usually found in very low numbers, reflecting the balance between blood cell production and the body’s needs.

Blasts and cancer

When a type of cancer is made up of blasts, it means that the cancer originates from these immature precursor cells. This is often seen in leukemias, which are cancers of the blood-forming tissues. For example, acute myeloid leukemia (AML) involves the rapid growth of myeloblasts, while acute lymphoblastic leukemia (ALL) involves the proliferation of lymphoblasts.

Cancers composed of blasts are particularly aggressive because these cells proliferate rapidly and do not mature into functional blood cells. This can lead to a variety of problems, including anemia (due to a lack of mature red blood cells), increased susceptibility to infections (due to a lack of mature white blood cells), and bleeding issues (due to a lack of platelets). The presence of a high number of blasts in the bone marrow or blood is a hallmark of these acute leukemias and is a critical factor in diagnosis and treatment planning.

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Atlas of Pathology