Hairy cell leukemia other diagnostic studies

Bone marrow biopsy
Most patients require a bone marrow biopsy for proper diagnosis. The bone marrow biopsy is used to confirm the presence of HCL and also the absence of any secondary disease. Abnormal white blood cells bearing hair-like projections from the cytoplasm are seen on blood film examination or bone marrow biopsy. The diagnosis can be confirmed by viewing the cells with a special stain, known as TRAP, or tartrate resistant acid phosphatase.

Flow cytometry
It is also possible to definitively diagnose hairy cell leukemia through a flow cytometry blood test which identifies characteristic proteins on the cell surfaces. These cancerous cells are larger than normal and positive for CD19, CD20, CD22, CD11c, CD25, CD103, and FMC7. Hairy cell leukemia-variant (HCL-V), which shares some characteristics with B cell prolymphocytic leukemia (B-PLL), does not show CD25 (also called the Interleukin-2 receptor, alpha). As this is relatively new and expensive technology, its adoption by physicians is not uniform, despite the advantages of comfort, simplicity, and safety for the patient when compared to a bone marrow biopsy.

Because a patient could have more than one similar disease, it is also necessary to rule out the presence of leukemias and lymphomas such as SMZL or B-PLL. The presence of these diseases is easily checked during a flow cytometry test, where they characteristically show different results. Careful review of bone marrow biopsy samples is also reliable for this purpose.