The present study was undertaken to gain information about the chemical composition and crystallographic feature of calcified tissues found in various fibro-osseous lesions, namely, ossifying fibroma/osteoma, osteosarcoma, and fibrous dysplasia. For references, we also examined dystrophic calcifications found in calcifying epithelial odontogenic tumor and necrotic lymphnodes, as well as cortical bones of human jaws at varying ages. The calcified materials were collected from 18 patients after surgical operation and then fixed in neutral formalin. Parts of the tissues were processed for histological examination, while the rest were freezedried and then pulverized for analyses. The results showed that all calcified specimens comprised microcrystals of carbonatoapatites , exceptionally accompanying the precipitation of calcium carbonate in one case of osteoma and whitlockite in two cases of necrotic lymphnodes. The crystallinity of apatite crystals in the pathogenic fibro-osseous tissues exhibited an improvement with tissue maturation, approaching the level of crystallinity of the age-matched bone crystals. In contrast, apatite crystals in the dystrophic calcifications exhibited higher crystallinity than those of the cortical bone and the fibro-osseous tissues. The conformity between the normal and pathogenic bony tissues supports the view that pathogenic calcification in the fibro-osseous lesions is a type of "biologically controlled mineralization" and that the common regulatory mechanism operates to induce carbonation of bioapatites even under pathologic environments.

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To elucidate the mechanism during reconstitution of murine organ-specific autoimmune lesions developing in the salivary and lacrimal gland from MRL/lpr mice into severe combined immunodeficiency (SCID) mice, mice which received salivary gland inflammatory cells from MRL/lpr mice were analyzed for cytokine gene expressions and autoantibody production. Successful transfer of autoimmune lesions developed at 8 wk after the intraperitoneal injection of 1X10⁶ cells. Flow cytometric analysis using peripheral blood mononuclear cells (PBMC) from transferred SCID mice was investigated every wk after the injection until 8 wk. Peripheral CD 4⁺ T cells were detected at 2 wk or more after the injection and their number gradually increased in the periphery. RT-PCR analysis on PBMC revealed that cytokine gene expressions including IL-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-6, IL-10, IL-12 (p 40) were detected at 8 wk after the injection. The number of peripheral B220⁺ B cells increased on PBMC during reconstitution in transferred SCID mice. Autoantibody production specific for the salivary gland was detected in sera from transferred SCID mice at 2 wk or more. These results suggest that cytokine gene stimulation and autoantibody production are involved in the development of organ-specific autoimmune lesions during reconstitution in transferred SCID mice.

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During our routine examination for surgical pathology of oral neoplasms, we found a case of basal cell adenoma with microcalcifications in tumoral stroma . Histopathology showed a tumor mass, covered with a thin fibrous connective tissue, and composed of cuboidal and/or columnar cells with round to ovoid nuclei. In parts of the intercellular stroma, numerous von Kossa's positive small granules were found. Under scanning electron microscopic observation, many small round granules in the stromal tissue were recognized. EPMA revealed that the granules consisted mainly of calcium and phosphorus. Immunohistochemistry showed the expression of osteopontin in the cytoplasm of neoplastic cells. Therefore, we thought that the osteopontin might have some role in the stromal microcalcification in this case of basal cell adenoma.

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Carcinoma arising as a primary tumor within the jaw is rare. According to the World Health Organization (WHO): International Histologic Classification of Tumours, primary intraosseous carcinoma (PIOC) is defined as a squamous cell carcinoma arising within the jaw, having no initial connection with the oral mucosa, and presumably developing from residues of the odontogenic epithelium. Although there have been reviewes of PIOC in the English literature, the clinicopathologic characteristics of PIOC among the Japanese have not been fully reviewed. This article reviewed twenty-seven cases of PIOC among Japanese and described the clinicopathological features.

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We report a case of metastatic prostate carcinoma to the mandible. A 76-year-old male was referred to our hospital due to a complaint of swelling in the left mandible. Roentgenographic findings revealed a radiolucent lesion in the angle of mandible, but scintigraphy did not reveal a specific accumulation in the body except in the mandible. A diagnosis of metastatic prostate carcinoma to the mandible was made through the biopsy specimens from the mandible and from urological examinations. Orchidectomy was performed after the administration of LH-RH agonist and anti-androgenic agent. Elevated blood levels of prostatic specific antigen and γ-seminoprotein were markedly decreased. Furthermore, these therapies were extremely effective not only to the primary lesion but also to the metastatic lesion in the mandible.

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We describe a case of pleomorphic adenoma associated with the formation of a large oval cyst in the right parotid gland in a 54-year-old Japanese man. The proliferative activity of the tumor cells was evaluated by counting the number of argyrophilic nucleolar organizer regions (AgNORs). The tumor, measuring 17×12×12 mm, was a clearly demarcated mass with an almost cystic appearance. It contained whitish cheese-like material. Histologically, the cyst cavity was filled with keratin and was lined by keratinizing squamous tumor cells. Flattened tumor cells were found in the hyalinized stroma. Adjacent islands of squamous metaplastic tumor cells and glandular tumor cells were present. The mean number of AgNORs per nucleus of tumor cells in the glandular portion, mildly keratinizing lining, highly keratinizing basal lining, highly keratinizing superficial lining, and flattened portion was 2.2±0.9, 1.7±1.1, 1.6±1.2, 1.2±0.9, and 1.3±0.8, respectively. Our results suggest that in some pleomorphic adenomas, small squamous metaplastic tumor islands might aggregate and lead to the formation of a large cyst in which the keratinizing tumor cells of the lining have higher proliferative activity than the flattened tumor cells in the hyalinized stroma.

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In general, it has been reported that peripheral ameloblastoma are less common and less aggressive than their intraosseous counter parts. In this paper, a case of peripheral ameloblastoma, which appear in a 63-year-old Japanese male, is described. The present case showed unusual invasive and aggressive features. Based upon the clinical course and histopathological features, biological behavior of this neoplasm is discused.

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This report presents a case of synovial cyst of the temporomandibular joint, which is rarely involved in this region. Histopathological characteristics of the cyst are described in detail. The diagnosis differentiating it from ganglion is also discussed, while synovial cyst is a true cyst lined by synovial cells, ganglion is a pseudocyst lined by dense connective tissues. Immunohistochemical staining may be helpful in identifing the lining cells of the synovial cyst.

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