Fig. 13.

a Moderate ED characterized by drop-shaped rete ridges, cells with increased nuclear:cytoplasmic ratio and dyskeratosis involving approximately half the thickness of the epithelium (H&E, original magnification ×200). b Severe ED characterized by bulbous rete ridges, dyscohesion, cells with increased nuclear:cytoplasmic ratio, dyskeratosis and slight nuclear pleomorphism and hyperchromasia involving greater than 2/3 the thickness of the epithelium (H&E, original magnification ×200). c Chronic bite/factitial keratosis (morsicatio mucosae oris) with parakeratosis and acanthosis (H&E, original magnification ×100). d Benign alveolar ridge keratosis with hyperkeratosis, wedge-shaped hypergranulosis and acanthosis (H&E, original magnification ×100). e Lichen planus exhibiting hyperkeratosis, epithelial atrophy, and interface inflammation (H&E, original magnification ×100)