Figure 1. Biopsy from left nasal cavity and bilateral maxillary sinus showing diffuse involvement by an aggressive lymphoid neoplasm, with atypical lymphocytes of varying sizes exhibiting prominent nuclear irregularity, apoptosis, and scattered mitotic figures admixed with eosinophils, macrophages, and plasma cells (A: H&E stain, 200× magnification). The tumor shows a very high proliferative index of Ki-67: ~80% (B). The neoplastic cells from the nasal cavity mass are diffusely positive by CD56 stain (C) and EBER in-situ hybridization (D). Of note, testing of the nasal cavity mass was performed at New York-Presbyterian Brooklyn Methodist Hospital, utilizing brownish-red EBER chromogenic staining. H&E – hematoxylin and eosin; EBER – EBV-encoded small RNA.