Abstract
Angioimmunoblastic T-cell lymphoma (AITL) is a distinct clinicopathological entity among peripheral T-cell lymphoma in the WHO classification. Whereas antigen “loss” or “deletion” of one or several pan-T cell antigens is a hepful feature of neoplastic lymphocytes in many T-cell lymphomas, no specific immunophenotypic patterns were available to recognize the tumour T-cells of AITL until recently. Indeed, Attygalle et al. reported that in this disorder neoplastic T-cells can be recognized by the aberrant expression of CD10 using immunochemistry in lymph nodes as well as in the involved extranodal sites. Lee et al. has also confirmed this specific phenotypic feature in cell suspension of lymph nodes using flow cytometry (FCM) in 3 cases of AITL. Here, we evaluated the CD10 expression by T cells in patients with AITL using four-colour FCM. The present study included lymph nodes (LN, n=10), peripheral blood (PB, n=5), bone marrow (n=1) and skin (n=1) samples from 13 patients with a diagnosis of AITL and with available cytologic histologic, immunologic and molecular data. Lymph nodes of reactive hyperplasia (n=13), B-cell lymphoma (n=23), other T-cell lymphoma (n=6) and peripheral blood from healthy donors (n=18) were used as control group. According with previous immunohistochemistry results, a fraction of T-cells expressed CD10 (using a level of at least 5% of all CD5+ cells) in 9/10 AITL lymph nodes with a mean number of 18%. Interestingly, among these 9 cases, 5 could be studied in peripheral blood also and all cases showed a fraction of T-cells expressing CD10, whatever be the lymphocytosis (median 1.1 109/l range 0.82 to 11.32 109/l). In three of these cases, tumoral T-cells presented also lack of surface CD3. In two cases of AITL diagnosed in LN, the aberrant CD10 expression by T-cells was found in bone marrow and skin, respectively. In the control group, T-cells were CD10 negative using the cut-off of 5%.
In conclusion, we demonstrate that the assessment of CD10 expression by neoplastic T-cells can be achieved by multi-colour FCM in lymph nodes and involved extranodal sites. Our results are concordant with the statement of Attygalle that CD10 expression by T-cells can be used as a marker of both malignancy and AITL type. In addition, this is to our knowledge the first description of circulating CD10 neoplastic T-cells in AITL. Further study with a larger series of patients is required to confirm these data, to standardize the cut-off of positivity and to evaluate the sensibility of FCM versus immunohistochemistry.
Figure
