ABSTRACT
To characterize angioimmunoblastic T-cell lymphoma [AILT] on morphological, immunohistochemical and molecular grounds and its association with Epstein-Barr virus [EBV] in Pakistani patients. Case series. Histopathology section of the Department of Pathology and Microbiology, The Aga Khan University Hospital, Karachi from January 01, 1992 to December 31, 2002. Over a period of 11 years archival biopsy material of 13 AILT cases [lymph nodes], identified on the basis of histological and immunohistochemical criteria, using REAL and WHO classifications, were retrieved from the files of Department of Pathology. Immunophenotyping was carried out by using CD45 [LCA], two T-cell markers CD45RO [UCHL1; monoclonal] and CD3 [polyclonal]. Polymerase chain reaction [PCR] was used to assess T-cell clonality for T-cell receptor [TCR]-b, g and immunoglobulin heavy chain [IgH] for FR2 and FR3 regions using primers recognizing conserved sequences of the variable [V], diversity [D] and joining [J] region segments. Association of EBV in AILT cases was studied by PCR and in situ hybridization [ISH]. This study showed AILT to constitute 0.71% of all NHLs [non-Hodgkin's lymphoma] [both T and B]. Immunohistochemical study revealed that the tumor cells were positive for CD45 [LCA], CD45RO [UCHL1] and CD3. All the 13 cases were largely negative for CD20 [L26], a B-cell marker, except few large scattered cells labelling. DNA extracted from all 13 lymph nodes was amplified using polymerase chain reaction [PCR]. PCR technique demonstrated clonal gene rearrangement of the TCR-b, g and IgH regions in 3 [23.1%], 7 [53.8%] and 3 [23.1%] AILT cases, respectively out of 13 cases. Association of EBV was seen in 11 out of 13 cases [84.6%] of AILT by PCR. By ISH the prevalence of EBV was detected in 8 [88.8%] out of 9 cases. The prevalence of AILT in the Pakistani population is slightly lower compared to other studies and that EBV is an etiological agent in pathogenesis of this disease