Other diagnostic studies for acute lymphoblastic leukemia include cytogenetics, bone marrow biopsy, flow cytometry, reverse transcriptase-polymerase chain reaction (RT-PCR) and flouroscence insitu hybridization (FISH).

• In Cytogenetics the following establishes whether the “blast” cells began from the B lymphocytes or T lymphocytes^[1]
  • Philadelphia chromosome^[2]
  • immunophenotyping
• DNA testing can establish how aggressive the disease is; different mutations have been associated with shorter or longer survival^[3]

• A biopsy is the only sure way to know whether leukemia cells are in the bone marrow
• Before the sample is taken, local anesthesia is used to numb the area. This helps reduce the pain.
• Bone marrow from the hipbone or another large bone is taken as biopsy.^[4]
• On biopsy the following is seen:^[5]
  • High number of lymphoblast
  • Hypercellular marrow with subtotal depletion of fat cells^[5]
  • Normal blood cell precursors
• A bone marrow biopsy and aspirate are routinely performed even in T-cell acute lymphoblastic leukemia to determine the extent of marrow involvement
• Malignant cells should be sent for conventional cytogenetic studies, as detection of the Ph1 t(9;22), myc gene rearrangements (in Burkitt), and MLL gene rearrangements add important prognostic information^[6]

• Flow cytometry should be performed to characterize expression of lineage-defining antigens and allow determination of the specific acute lymphoblastic leukemia subtype.^[7][8]
  • CD19
  • CD20
  • CD22
  • CD24
  • CD79a

• In addition, for B-cell disease, the malignant cells should be analyzed using RT-PCR and FISH for evidence of the bcr-abl fusion gene^[9]
• This last point is of utmost importance, as timely diagnosis of Ph1 acute lymphoblastic leukemia will significantly change the therapeutic approach.^[6]