PTGS2 and neoplasm: Tumour glandular luminal eosinophilic secretions containing necrotic debris (dirty necrosis) stain positive to PAS and MUC1 positive whereas those without necrotic debris stain MUC2 positive [13, 31] It could therefore be suggested that CRCs harboring dirty necrosis may have a molecular characteristic different from others which might influence or be influenced by COX-2 expressivity.