# The importance of bone marrow biopsy for chronic myeloid leukemia classification—a case report

## TL;DR

A case report shows how bone marrow biopsy helped correctly diagnose a complex form of chronic myeloid leukemia.

## Contribution

The report emphasizes the critical role of bone marrow biopsy in identifying rare diagnostic patterns in CML.

## Key findings

- Bone marrow biopsy revealed lymphoid blast crisis in a patient suspected of having CML in chronic phase.
- Flow cytometry detected a small percentage of lymphoblasts, confirming the blast crisis diagnosis.
- The case highlights the necessity of combining multiple diagnostic techniques for accurate CML classification.

## Abstract

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by the BCR::ABL1 rearrangement, usually diagnosed by data of peripheral blood, bone marrow cytology, cytogenetics, and the detection of the BCR:ABL1 rearrangement. An accurate diagnosis, including the precise phase of the disease, is essential to guide appropriate treatment. We present the case of a patient admitted at our Institution with the hypothesis of CML in chronic phase, based on clinical and bone marrow cytological findings. Bone marrow biopsy showed some areas with morphologic features of CML in chronic phase but also sheets of B lymphoblasts, compatible with lymphoid blast crisis. Flow cytometry detected 1.18% of lymphoblasts. This report clearly illustrates the importance of the examination of bone marrow by several techniques. It highlights the importance of the biopsy in recognizing anomalous immunomorphological patterns, which can lead to diagnostic and therapeutic changes in CML.