Thyroglossal duct cyst is an unusual developmental cyst of the neck, arising anywhere from the base of the tongue to the thyroid gland. It may develop from epithelial remnants of the thyroglossal duct. To determine whether apoptotic cell death or cell proliferation has a role in the formation of this cyst, apoptosis-related factors and cell proliferation markers were immunohistochemically examined in the thyroglossal ducts and thyroglossal duct cysts. Expression of Lewis^y antigen was detected in the lining epithelium of all thyroglossal duct cysts and in the luminal epithelium of all thyroglossal ducts. Immunoreactivity for p53 protein was detected only in the lining epithelium with squamous metaplasia in thyroglossal duct cysts and was not detected in the thyroglossal ducts. Expression of bcl-2 protein was detected in several thyroglossal duct cysts as well as in the thyroglossal ducts, and the proportion of cases positive for bcl-2 protein was significantly higher in thyroglossal duct cysts than in the thyroglossal ducts (p<0.05). The ratio of Ki-67-positive cells (Ki-67-LI) in thyroglossal duct cysts was significantly higher than that in the thyroglossal ducts (p<0.05). These immunohistochemical features suggest that apoptosis-related factors and cell proliferation markers might play specific roles in cyst formation in the thyroglossal ducts.

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TGF-β1, TGF-βRI and TGF-βRII were examined in 80 cases of squamous cell carcinoma (SCC), 26 cases of leukoplakia and 10 cases of early carcinoma in leukoplakia of the tongue by immunohistochemical methods. Nine cases of SCC were analyzed immunoelectron microscopically. Expression of TGF-β1 was enhanced in SCC compared with early carcinoma in leukoplakia and with leukoplakia (P<0.05). Expression of TGF-βRI and TGF-βRII was significantly reduced in SCC compared leukoplakia (P<0.01). Early carcinoma in leukoplakia did not show enhanced expression of TGF-β1 but expression of TGF-βRI and TGF-βRII was reduced, compared with leukoplakia (P<0.05). Immunoelectron microscopically, TGF-β1 immunostaining was scattered in the cytoplasm of tumor cells and TGF-βRI and TGF-βRII stainings were present on the tumor cell membrane and in the capillary endothelial cells of the stroma. In conclusion, tumorigenesis in the tongue may involve escape from cellular regulation of TGF-β1 by reduced expression of TGF-βRI and TGF-βRII.

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The purpose of the present study was to observe the three-dimensional images of histological patterns of salivary gland tumor by optical sections in confocal laser scanning microscope (CLSM). We observed luminal structures in pleomorphic adenoma (PA), comedo necrosis in salivary duct carcinoma (SDC), and cribriform pattern in SDC and in adenoid cystic carcinoma (ACC). CLSM images showed that a certain type of luminal structures formed duct-like structures in PA, and that most of luminal structures of cribriform patterns were cavities. The present study indicated that 3 D images might distinguish between ductal structure and cystic cavity. Further studies on 3 D image of the histological pattern may provide more useful findings to make a final diagnosis.

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A 70 year-old man noticed a mass gradually enlarging in the left parotid gland region three months before consulting our hospital. Histopathologically, the tumor consisted of two patterns of cellular growth, involving ductal cells in the inner and clear cells in the outer layers. From the microscopic and immunohistochemical findings, the tumor was diagnosed as an epithelial myoepithelial carcinoma. Confocal laser microscopy further suggested that the clear cells had malignancy. From these results, it was suggested that the clear cell (outer cell) played a major role in proliferation and in the potency of malignancy, although epithelialmyoepithelial carcinoma was defined as a low malignant cancer showing a two-cell pattern.

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A follicular mixed B-cell lymphoma arising in the submandibular gland is reported. The patient was a 25-year-old woman, and other than the left submandibular lesion there were no symptoms such as lymph node swelling. After resection of the mass, it was diagnosed as malignant lymphoma, follicular B-cell, mixed type on the basis histopathological and immunohistochemical findings. LCA, L-26 and CD-10 were reactive and UCHL-1, CD-68 were negative. Proliferating centrocyte-like cells in the follicular lesions were also immunoreactive for Bcl-2. The patient is tumor-free after 2 years follow up. As primary malignant lymphoma of salivary glands is uncommon, we have reported the experiences with this case.

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Pseudocyst of the maxillary sinus is a relatively rare lesion which has not been clearly defined. This paper presents a case of pedunculated pseudocyst of the maxillary sinus. The cyst adhered to the inferior border with narrow fibrous tissues and was pedunculated in the right maxillary sinus. It was histologically examined by microscopic preparations cut serially. The cyst wall was composed of thin fibrous tissue, and lining epithelium of the inner surface was not present. Pseudocyst should be differentiated from mucocele and retention cyst of the maxillary sinus.

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The authors report the rare case of a granular cell lesion of the gingiva overlying a maxillary incisor tooth that was delayed in eruption in a 9-year-old Japanese boy. The lesion was composed of a nodular aggregation of ovoid-shaped cells with eosinophilic and granular cytoplasm, which was immunohistochemically positive for LDL, CD68, HLA-DR, cathepsin D and heparanase. These cells were neither positive for S-100 protein, vimentin, desmin nor myosin. The results suggested that this lesion is a sort of xanthoma, but neither granular cell tumor nor congenital epulis. The etiology of this lesion is unknown, but it seems to be associated with tissue remodeling processes of the pericoronal mesenchymal tissue during tooth eruption. Such an unusual pericoronal tissue containing a xanthomatous lesion may be one of the causes for delay in tooth eruption.

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