Aberrant antigenic expression in extranodal NK/T-cell lymphoma: a multi-parameter study from Thailand

By using tissue microarray (TMA), immunohistochemical study and EBV encoded RNA (EBER) in situ hybridization were performed. T-cell receptor (TCR) gene rearrangement, EBV subtyping, and LMP-1 gene deletion were studied on the available cases.There were 22 cases eligible for TMA. ENKTL were positive for CD3 (91%), CD5 (9%), CD7 (32%), CD4 (14%), CD56 (82%), TIA-1 (100%), granzyme B (95%), perforin (86%), CD45 (83%), CD30 (75%), Oct2 (25%), and IRF4/MUM1 (33%). None of them was positive for βF1, CD8, or CD57. TCR gene rearrangement was negative in all 18 tested cases. EBV was subtype A in all 15 tested cases, with 87% deleted LMP-1 gene. Cases lacking perforin expression demonstrated a significantly poorer survival outcome (p = 0.008).The present study demonstrated TIA-1 and EBER as the two most sensitive markers. There were a few CD3 and/or CD56 negative cases noted. Interestingly, losses of CD45 and/or CD7 were not uncommon while Oct2 and IRF4/MUM1 could be positive in a subset of cases. Based on the present study in conjunction with the literature review, determination of PCR-based TCR gene rearrangement analysis might not be a useful technique for making diagnosis of ENKTL.T-cell lymphoma, especially extranodal NK/T-cell lymphoma, nasal type (ENKTL), has a higher incidence in Asian and Latin American countries than the Western [1-3]. In a recently published series of 71 consecutive mature T- and NK-cell lymphomas in Thailand, ENKTL accounted for 31%, the most common subtype which is higher than other types including anaplastic large cell lymphoma (18%), angioimmunoblastic T-cell lymphoma (14%), peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS, 13%), and other less common subtypes [4].ENKTL is a type of non-Hodgkin lymphoma, most common in upper aerodigestive tract, particularly nasal cavity [2,3,5]. ENKTL is believed to be derived from either NK- or cytotoxic T-cell, but the former is more common [5,6]. T-cell receptor (TCR) gene rearrangement is mos