Histologic subtypes of nasal NK/T-cell lymphomas and detection of PI9 and aC3 in tumors cells of nasal NK/T-cell lymphomas. (A) Example of a lymphoma with a predominant small to medium-sized cell component with mild atypia. (B) Example of a lymphoma with pleomorphic large-cell features. (C) Example of a nasal NK/T-cell lymphoma scored as positive for PI9, with virtually all tumor cells surrounding glands positive. (D) Another nasal NK/T-cell lymphoma scored as negative for PI9 (< 10% tumor cells positive). A few scattered cells serve as internal positive control. (E) Example of a nasal NK/T-cell lymphoma with more than 10% aC3⁺ tumor cells (brown nuclear staining), whereas panel F illustrates a case with less than 10% aC3⁺ tumor cells. Only rare scattered cells with brown nuclear staining are present. Original magnification, × 400 for panels A-B, × 100 for panel C, and × 200 for panels D-F). Images were captured with a Zeiss Axioskop2 microscope (Oberkochen, Germany) and Neofluar 100×/0.1 NA optical lenses (Zeiss). Photographs were taken with a DP70 Olympus camera (Tokyo, Japan). Image acquisition was performed with Olympus DP Controller 2002, and images were processed with Adobe Photoshop 7.0 (Adobe Systems, San Jose, CA).