Comparison of LMP-1 Immunostaining Patterns with EBER-ISH Reactivity
Jaiyeola Thomas. Louisiana State University Health Science Center, Shreveport, LA
Background: Detection of Epstein-Barr virus (EBV) in tissue may be achieved by various methods including EBV-encoded RNA (EBER) in-situ hybridization (ISH) and immunohistochemistry (IHC) for latent membrane protein (LMP-1). EBER-ISH is recommended as the best test for detecting and localizing latent EBV in tissue samples, however, manual IHC is more readily available in low-resource settings. Though membrane and/or cytoplasmic dot-like staining of IHC for LMP-1 is interpreted as positive, diffuse and granular cytoplasmic reactivity are sometimes seen and interpretation of these is uncertain. The IHC LMP-1 and EBER-ISH reaction in nasopharyngeal carcinomas (NPC) are compared to determine the reliability of these reactions.
Design: All NPC identified over a 4-year period in the Pathology database of UCH, Ibadan were retrieved and reviewed. IHC for LMP-1 and EBER-ISH were performed. Both staining reactivity was compared to determine the diagnostic accuracy of IHC. RNA and negative controls were performed.
Results: 32 cases of NPC were identified; 18 LMP-1 IHC are negative and 8 cases are considered positive with membrane and cytoplasmic staining, including 5 cases with dot-like, Golgi pattern. Equivocal LMP-1 IHC diffuse or granular cytoplasmic staining are present in 6 cases all are EBER-ISH positive.
12 cases showed discordant reaction; all are LMP-1 IHC negative, EBER-ISH positive. EBER-ISH signal is localized to the nuclei.
Conclusions: LMP-1 IHC is more economical, rapid and easily incorporated into routine laboratory compared to EBER-ISH. Diffuse, granular and dot-like Golgi cytoplasmic LMP-1 IHC reactvity should be considered positive at least, in NPC.
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 292, Wednesday Morning