EBV-positive Diffuse Large B-Cell Lymphoma, NOS in a Filipino Patient: Mimickers and Essential Ancillary Studies

Abstract

Epstein-Barr virus positive diffuse large B-cell lymphoma (EBV+ DLBCL) is prevalent among Asians but is underreported in the Philippine setting. We report the case of an 88-year-old male who presented with difficulty swallowing. CT scan showed an ill-defined soft tissue focus with calcifications in the supraglottic to hypopharyngeal region measuring approximately 2.6 x 1.7 x 1.5 cm, and multiple lymphadenopathies in the head and neck. Biopsy of the masses at the left tonsil, left arytenoid mucosa, pyriform sinus, and aryepiglottic fold showed large lymphoid cells with several Reed-Sternberg-like cells in a background of small lymphocytes, neutrophils, few eosinophils and histiocytes. A panel of immunohistochemical stains and EBER-ish were performed to differentiate among six entities that were morphologically similar to the patient’s case, namely, classic Hodgkin lymphoma, T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL), DLBCL, NOS, anaplastic variant, B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and classic HL (gray zone lymphoma), and infectious mononucleosis (IM). The neoplastic cells expressed CD20, CD30, CD45, PAX5, CD10, MUM-1, BCL6, BCL2, and c-myc, while CD3, CD15 and ALK-1 were negative. The cells of interest also showed nuclear staining (30-40%) on Epstein-Barr virus encoding RNA in-situ hybridization (EBER-ish). The Ki-67 showed a proliferation index of 40-50%. Given the differences in prognosis and treatment among these diseases, judicious use of immunostains and EBER-ish is recommended for accurate diagnosis.