2012 年 10 巻 4 号 p. 372-383
Keratocystic odontogenic tumor shows a relatively high rate of recurrence with daughter cysts and epithelial islands. Determining evidence of the daughter cysts or epithelial islands is therefore important for deciding treatment and assessing the prognosis. However, the evidence is often difficult to confirm from preoperative imaging and biopsy. Using histopathological and immunohistochemical methods on surgical specimens, the author conducted fractal analysis of tumor parenchymal-stromal border shape, provided feedback on biopsy materials, and investigated the utility of the methodology. The materials used in the present study were histopathologically divided into a group with neither daughter cysts nor epithelial islands (Group 1) and a group with either daughter cysts or epithelial islands or both (Group 2). In the epithelial basal lamina, rete ridges presenting an inverted conical shape were directly observed in Group 1 and “budding” with an alveoli-like spherical shape was seen in Group 2. The results of fractal analysis on the rounded form of the basement membrane showed a complex shape with a significantly higher fractal dimension in Group 2 than in Group 1. Immunohistochemically, the MIB-1 labeling index in the basal lamina, indicative of cell proliferative activity, the microvessel density (MVD) measured 200 μm immediately below the basal lamina, indicative of vascular distribution for tumor growth, and the microvessel area (MVA) were all significantly higher in Group 2 than in Group 1. These findings suggested that fractal analysis of the basement membrane curve shape and a comparative analysis of MVD and MVA were useful as factors indicating the presence of daughter cysts and epithelial islands, which are causes of recurrence, suggesting a close association with the neoplastic characteristics.
