Kozo Mushimoto

A Clinicopathologic Study of Ameloblastoma

One hundred four ameloblastomas, 97 in the mandible, five in the maxilla, and two in peripheral locations, were studied. A consistent correlation between the age of the patient and the radiographic or histologic type of mandibular ameloblastoma was observed. There was a tendency for ameloblastomas of the follicular type to show a multilocular or soap bubble appearance and for those of the plexiform type to show a unilocular appearance. Recurrent ameloblastomas had a predominantly multilocular appearance. Histologically, the ameloblastomas in the maxilla were of the follicular type.

Prognostic evaluation of ameloblastoma based on histologic and radiographic typing

Ninety-one patients with ameloblastoma of the mandible were studied. Among the 23 patients treated with radical surgery the recurrence rate was 8.7%, whereas the rate of 45.65% in the 68 conservatively treated patients. The prognoses of the patients treated by conservative surgery were analyzed based on the histologic and radiologic criteria of each lesion. The recurrence rate was significantly higher in the follicular type (56.8%) than in the plexiform type (32.3%). Recurrence was seen more frequently in the multilocular or soap bubble type (60.7%) than in the unilocular type (35.0%). When the recurrence rate was compared between patients aged less than 20 years and patients aged greater than or equal to 20 years, younger patients had better prognoses. It was concluded that there is a prognostic value in the histologic, radiographic, and age factors.

Correlation of E‐and P‐cadherin expression with differentiation grade and mode of invasion in gingival carcinoma

The expression pattern of two Ca2+‐dependent cell‐cell adhesion molecules, E‐and P‐cadherin (CD), in 25 primary gingival squamous cell carcinomas (SCC) was examined immunohistochemically. The occurrence of reduced‐type expression of both E‐and P‐CD increased significantly with the grade of carcinoma differentiation, culminating in a complete loss of P‐CD in poorly differentiated SCC. The occurrence of reduced‐type P‐CD expression also increased significantly with the mode of invasion, as was the case with E‐CD. Furthermore, no P‐CD molecules were detected in one of the six SCC having a diffuse, cord‐like invasion and in three of the six having a diffuse type of invasion. These findings suggest that the down‐regulation of these cell adhesion molecules closely correlates with the differentiation grade and mode of invasion of gingival SCC.

Aneurysmal bone cyst of the mandible

Aneurysmal bone cyst is a multilocular cystlike lesion in the bone which is filled with blood. In 1942, Jaffe and Lichtenstein1 separated a cystic lesion containing numerous pools of blood from other cysts, and in 1950 Lichtenstein2 proposed the name “aneurysmal bone cyst” for this entity. He stated that the aneurysmal bone cyst usually occurred in vertebrae, clavicle, rib, and limb bones and produced eccentric bone expansion with numerous pools of blood. The histologic findings showed that spongy bone and marrow were replaced by a fibrous tissue in which hemorrhage, giant cell reaction, and reparative new bone formation were observed. Lichtenstein3 reported statistically that vertebrae and limb bones were commonly affected, constituting about 60% of the total number of cases. Studies by Biesecker et al4 and Ruiter et al5 showed almost the same result. The aneurysmal bone cyst rarely affects the craniofacial bones. Biesecker reported only two cases in the mandible in 66 cases, and Ruiter reported one case in the maxilla in 105 cases. Daugherty6 mentioned that only 2% of these lesions were in the facial bones.

Calcifying Odontogenic Cysts: Co-Expression of Intermediate Filament Proteins, and Immunohistochemical Distribution of Keratins, Involucrin, and Filaggrin

The epithelia lining the cyst of five cases of calcifying odontogenic cyst (COC) were evaluated immunohistochemically with the use of monoclonal antibodies (MoAbs) against keratin (PKK1, KL1, K4.62, K8.12) and vimentin, and polyclonal antisera agonist involucrin and filaggrin. Epithelial lining of COC was classified into 1) thin squamous-cell epithelium, 2) ameloblastoma-like, and 3) thin or 4) thick calcifying odontogenic epithelium. Foci consisting of ghost cells or calcified cells were categorized as calcifying epithelial odontogenic tumor (CEOT). Thin squamous-cell epithelium reacted with PKK1, KL1, K4.62, K8.12, and anti-vimentin MoAbs, thus demonstrating the co-expression of keratin and vimentin. Ameloblastoma-like cells showed positive staining with PKK1, KL1, and sometimes with anti-vimentin. Thick calcifying odontogenic epithelial lining showed stratification of cell layers, and the most strikingly reactive zone was the upper intermediate layer, which showed the presence of keratin, involucrin, and a small amount of filaggrin. Cells of this layer might be the most differentiated type of cells in COC. Undifferentiated odontogenic cells of COC masses were characterized by co-expression of keratin and vimentin, and by the absence of involucrin and filaggrin. All ghost cells were devoid of any immunostaining except for filaggrin, which was rarely positive, but eosinophilic or basophilic cells surrounding the ghost cells showed intense staining for all keratin proteins except vimentin.

Prefabricated Vascularized Bone Graft Using Autologous Tissue, Biomaterials, and Growth Factors: A New Technique for Bone Reconstruction

Although clinically, grafting of vascularized autologous bone has been preferably performed, there are some disadvantages for this grafting therapy, such as the limited availability of donor site and the clinical difficulty to harvest the bone graft of desired shape and size. As one trial, we have designed a prefabricated vascularized bone graft by combining autologous vessels, particulate cancellous bone and marrow (PCBM), and β-tricalcium phosphate (β-TCP) with a biodegradable membrane. However, the volume of vascularized bone tissue newly formed was small and the density was low. In this study, the controlled system of basic fibroblast growth factor (bFGF) was combined with the conventional preparation method to improve the nature of vascularized bone graft. The femur vessels of rabbits were rolled with a membrane of L-lactide-ε-caploractone copolymer. Hydrogel microspheres of gelatin were prepared as the release carrier of bFGF. Autologous PCBM harvested from the beforehand tibia of rabbits was mixed with β-TCP granules with or without the microspheres incorporating bFGF and packed into the rolled membrane. When bone formation was assessed at different time intervals, additional mixing of bFGF significantly increased the volume of vascularized bone tissue compared to that without bFGF. It is concluded that combination of bFGF release system was a promising method to prefabricate the bone graft of large size with good blood circulation.

Ultrastructural localization of collagen type IV and laminin expression in the epithelial basement membrane of oral carcinomas

Epithelial basement membrane in oral carcinomas was examined by immunoelectron microscopy using anticollagen type IV and antilaminin antibodies. Intense and irregularly increased immunostaining was observed at the boundary between carcinoma cells and stromal tissue. Heterotopic immunostaining was found in the enlarged intercellular spaces of peripheral carcinoma cells. In addition, rough endoplasmic reticulum (rER) and vesicles in these cells were frequently stained. These findings suggest an increased synthesis and secretion of basement membrane components at the invading edge of the tumor, and also suggest that some oral carcinomas may spread into the surrounding tissue without apparent loss of the basement membrane.