blast cell
An immature hematopoietic cell characterized by large size, high nuclear-to-cytoplasmic ratio, and prominent nucleoli.
Full Definition
Blast cells are primitive, undifferentiated hematopoietic precursors that normally comprise less than 5% of bone marrow cells and are rare in peripheral blood. These cells are characterized morphologically by their large size, fine chromatin pattern, prominent nucleoli, and basophilic cytoplasm with high nuclear-to-cytoplasmic ratio. In hematologic malignancies, blast cells accumulate abnormally due to impaired differentiation and excessive proliferation. The percentage of blasts in bone marrow or peripheral blood is crucial for diagnosing acute leukemias (typically ≥20% blasts) and distinguishing them from other hematologic disorders.
Usage
Usage note: Often simply called 'blasts' in clinical contexts. Specific blast types (lymphoblasts, myeloblasts) require additional characterization studies.
In Context
- "The peripheral blood smear revealed 45% blast cells, concerning for acute leukemia." — Laboratory report
- "Morphologic examination identified blast cells with Auer rods, suggesting acute myeloid leukemia." — Pathology findings