Epulis fissuratum is microscopically similar to routine irritation fibroma except that the chronic inflammatory cells are more numerous and the surface epithelium is much more likely to be ulcerated, especially in the base of the clefts between the redundant folds of tissue. The intact surface epithelium is often quite acanthotic, with occasional lesions showing enough elongation of rete processes to justify a secondary diagnosis of pseudoepitheliomatous hyperplasia [click here for more detail]. The pathologist must be very cautious about misinterpreting this epithelial hyperplasia as well-differentiated squamous cell carcinoma or verrucous carcinoma, especially with samples showing elongated rete processes cut tangentially or at right angles, appearing as separate islands of epithelium deep in the stroma. It is important, in this regard, to understand that carcinoma in association with epulis fissuratum is extremely rare.