Loss of LEF-1 expression as a diagnostic indicator for extranodal NK/T-cell lymphoma: An immunohistochemical study of 88 cases.

Purpose: Extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is not a uniform entity but consists of various disease subtypes associated with Epstein-Barr virus (EBV) infection. Lymphoid enhancer binding factor-1 (LEF-1), a member of the T-cell factor/LEF family of transcription factors, plays a significant role in NK-cell and T-cell development. We aimed to explore the expression of LEF-1 in ENKTL and evaluate the applicability of LEF-1 in the diagnosis of ENKTL.
Methods: The expression of LEF-1 was investigated in tissue samples harvested from patients with ENKTL by immunohistochemistry.
Results: LEF-1 staining was not observed in 85 of 88 ENKTL cases (97%). Eighty-six of the 88 cases (98%) were positive for CD56, whereas all the tested cases were negative for both CD16 and CD27. Of the cytotoxic T-cell-like features studied, 81 cases (92%) were negative for CD8, 85 of 88 cases (97%) were immunoreactive for the recombinant linker for activation of T cells (LAT), all (100%) were immunoreactive for TIA-1, 85 (97%) were immunoreactive for granzyme B and 65 (74%) were immunoreactive for perforin.
Conclusion: Loss of LEF-1 expression is a highly specific diagnostic indicator of ENKTL.
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