Fig. 2

Histological and immunohistological features of the first nasopharyngeal biopsy. a. There were several irregular-shaped cell islands found in some areas of tissue. The cells were syncytial appearance with indistinct cell borders, oval vesicular nuclei and large central nucleoli. b In other areas, diffuse infiltration of monomorphic plasmacytoid-appearing cells was observed in the subepithelial tissue. c. Immunohistochemically, syncytial cell islands were diffusely positive to pan-CK (AE1/AE3). d. In situ hybridization assay showed that the syncytial cell islands were EBERs-positive. e. However, the monomorphic plasmacytoid cells were diffusely immunoreactive to CD138, but lack the expression of CD20 f. g. The presence of kappa light chain restriction was also detected in plasmacytoid cells. h. In situ hybridization assay revealed that plasmacytoid cells were EBERs-negative. a-b, HE staining with original magnification × 400; c, e-g, immunohistochemical staining with original magnification × 400; d, h, in situ hybridization for EBERs with original magnification × 400)