THE RETROCUSPID PAPILLA AND FACTOR XIIIA - AN EPIDEMIOLOGIC AND HISTOMORPHOLOGIC STUDY

The retrocuspid papilla (RCP) is a poorly recognized entity. In one pa rt of our study, we found 10 cases of lesions clinically compatible wi th RCP in 1150 consecutively examined patients. In another part of the study, we found 15 cases of RCP in more than 2000 consecutive cases o f oral mucosal hyperplasia submitted as surgical biopsies during 1989- 92. The lesions were situated in the attached gingiva, lingual to the two mandibular canines, often bilaterally. They were covered by normal pink mucosa with a size and a height each of 2-3 mm. Histologically, the RCP was a broad-based, often downfolded hyperplasia, covered with a parakeratinized epithelium of normal thickness. The rete pegs were o ften elongated and blunt, frequently bent inward toward the center. Th e lamina propria was mostly composed of a loosely arranged, delicate, fibrous connective tissue. The lesions could be classified into two gr oups by the presence or absence of stellate and occasionally multinucl eated fibroblasts. Immunohistochemical staining with an FXIIIa antibod y disclosed a population of reactive spindle-shaped cells, mainly loca lized in the connective-tissue papillae. These cells may be of pathoge netic importance.