Blast Crisis Characteristics

Key Laboratory Findings

The International Bone Marrow Transplant Registry and WHO criteria define blast crisis as ≥30% blasts in peripheral blood or bone marrow, with elevated blast percentage being a key characteristic, according to the National Comprehensive Cancer Network 1, 2
Significant basophilia, often ≥20% basophils in peripheral blood, is a notable finding in blast crisis, as reported in Blood 2, 3
Thrombocytopenia, characterized by a persistent low platelet count (<100 × 10^9/L) unrelated to therapy, is a common feature of blast crisis, according to Blood 2, 3
The presence of immature cells, such as myelocytes and promyelocytes, in peripheral blood is a key laboratory finding in blast crisis, as defined by the National Comprehensive Cancer Network 1

A high blast percentage, ≥30% blasts in bone marrow (International criteria) or ≥20% (WHO criteria), is a critical characteristic of blast crisis, as reported by the National Comprehensive Cancer Network 1, 4
Large foci or clusters of blasts in bone marrow biopsy are a distinctive feature of blast crisis, according to Blood and the National Comprehensive Cancer Network 3, 4
Dysplastic features are often present in multiple cell lines in blast crisis, as noted in Blood 5

Myeloid blast crisis accounts for 70-80% of cases, while lymphoid blast crisis accounts for 20-30% of cases, although this fact is from Praxis Medical Insights, it is still a relevant guideline summary point 6

Basophilia is more prominent in blast crisis than typically seen in de novo acute leukemia, helping to distinguish between the two conditions, as reported in Blood 2, 3