Significant Haematogone Proliferation Mimicking Relapse in Acute Lymphoblastic Leukaemia on Therapy

Haematogones are benign B lymphoid precursors which may mimic neoplastic lymphoblasts and pose diagnostic difficulty especially when the percentage of haematogones exceeds 10% in the bone marrow. Flow cytometric analysis with combination of CD19/CD10/CD20/CD34/CD38/CD58 can be used to differentiate the two depending upon the difference in the fluorescence intensity between blasts and haematogones. We hereby present a case of Common Acute Lymphoblastic Leukaemia Associated Antigen (CALLA) positive Acute Lymphoblastic Leukaemia (ALL), in which patient presented with haematogone proliferation in bone marrow after 6 months of chemotherapy mimicking relapse. The distinction was made on flow cytometric immunophenotyping by using optimal antibody combination. Distinction of benign haematogones from neoplastic lymphoblasts is essential for disease management in cases of post chemotherapy or post marrow transplant, especially in patients of ALL. Flow cytometric immunophenotyping is reliable to distinguish haematogones from residual lymphoblasts in almost all cases when optimal antibody combinations are used.