Abrupt keratinization and Comedo-necrosis among non-maturing tumor nest. (A) A representative HPV-OPC case with abrupt keratinization (arrows); some are located peripheral to tumor nest and others are among non-maturing tumor cells. (B) A representative HPV-OPC case with comedo necrosis among non-maturing tumor nest (double arrows); coagulative necrosisis seen among non-maturing tumor cell nest. A single arrow indicate abrupt keratinization. [A & B, Hematoxylin and eosin staining with original magnification, original magnification, x200 for both].