الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Background. Non-Hodgkin Lymphomas (NHL) are a heterogeneous group of malignancies of the immune system; diffuse large B-cell lymphoma and Burkitt’s lymphoma are among its most common subtypes. Recently, it is widely believed that cancer stem cells play critical roles in the initiation, metastasis, and relapse of cancers. However, no sufficient data supported the presence of cancer stem cells in NHL of the head and neck.
Purpose. To detect cancer stem cells in diffuse large B-cell lymphoma and Burkitt’s lymphoma using immunohistochemical expression CD34, a widely used marker for identification and detection of hematopoietic stem cells.
Methodology. The present work was performed on archival paraffin blocks of diffuse large B-cell lymphoma and Burkitt’s lymphoma. The mean count and mean area of the positive CD34 cells were assessed by the image analyzer computer system using the software Leica Qwin 500.
Results. The results showed positive CD34 immunoreaction in 90% of the diffuse large B-cell lymphoma cases, and 70%of the Burkitt’s lymphoma cases, denoting presence of cancer stem cells in both tumors. Diffuse large B-cell lymphoma showed significantly higher mean count and mean area of positive CD34 cells than those of Burkitt’s lymphoma.
Conclusion. Cancer stem cells are present in both diffuse large B-cell lymphoma and Burkitt’s lymphoma and may be a common origin of these lesions. Diffuse large B-cell lymphoma may be more aggressive than Burkitt’s lymphoma. The level of cancer stem cells may be a valuable prognostic tool which is directly proportional with more aggressive behavior and poor prognosis.CD34 is a valuable cancer stem cell marker in diffuse large B-cell lymphoma and Burkitt’s lymphoma and can be used as prognostic marker in these lesions.