Human salivary gland stem/progenitor cells remain dormant even after irradiation.

Progressive loss of salivary gland function occurs in most patients undergoing head and neck radiotherapy. It is unclear whether adult salivary gland tissue contains stem/progenitor cells. In this study, we used a colony assay to clarify the presence of stem/progenitor cells in adult submandibular glands after irradiation. We developed a novel culture system that promotes single-cell colony formation with low density culture of irradiated and non-irradiated adult human submandibular gland cells using serum-free medium following serum-supplemented medium. The cells from all samples, except those obtained from the oldest patient who received the highest radiation dose, expressed acinar, ductal, and myoepithelial cell-lineage markers with reverse transcription-polymerase chain reaction (RT-PCR) and immunostaining. A sub-culture of these colonies with serum-free medium showed high multipotency. These results are the first description of presence of salivary gland stem/progenitor cells with self-renewal, high proliferation and multipotent differentiation activity in salivary glands, even after irradiation. The survival of the cells depends on radiation dose and cell aging.

Osteosynthesis and simultaneous irregular trifocal distraction osteogenesis for segmental mandibular defect after tumor ablative surgery: a case report.

OBJECTIVE: This paper describes a case of secondary mandibular bone reconstruction performed to place dental implants. Osteosynthesis and simultaneous irregular trifocal distraction osteogenesis were documented. PATIENT: The patient was a 51-year-old man with recurrent ameloblastoma of the mandible. Segmental mandibulectomy for tumor ablation and immediate mandibular reconstruction were performed. Because the volume of reconstructed bone was insufficient to place dental implants, trifocal distraction osteogenesis (vertical and horizontal distraction osteogenesis) was performed. Because the mandible had lost its continuity, osteosynthesis was performed simultaneously. RESULTS: Through this procedure, the bone was well augmented. Absorption of the distracted bone was not seen. Adequate-length implants were placed. CONCLUSION: Irregular trifocal distraction osteogenesis synchronized with osteosynthesis shortened the treatment period and produced stable bone augmentation for placement of dental implants. Therefore, this procedure could be indicated for complicated segmental mandibular bone defects.

Salivary duct carcinoma in the mandible: a case report.

Salivary duct carcinoma (SDC) is a distinctive and aggressive neoplasm. The most frequent site of origin is the parotid gland, followed by the submandibular gland. SDC originating in the minor salivary glands, particularly in the ectopic glands within the mandible, is extremely rare. We describe a 62-year-old man with SDC in the mandible, who presented with a painless lump in the right submandibular region (later identified as lymph node metastasis) and ipsilateral mental nerve palsy. Histologic examination after ablative surgery revealed SDC originating in the mandible and cervical nodal metastases spreading to levels I-III. The patient remains alive 59 months after presentation as a result of postoperative full-dose irradiation and regular intensive chemotherapy using TXT, 5-FU, and CDDP. However, the patient has local recurrence and distant metastases to the lung and brain. In this report, we also discuss the specific diagnostic criteria and developmental theories of intraosseous salivary gland tumors.

Gene mutation analysis and immunohistochemical study of beta-catenin in odontogenic tumors.

In the present study the significance of nuclear/cytoplasmic expression of beta-catenin (CTNNB1) and mutation of the CTNNB1 gene (CTNNB1) in odontogenic tumors was examined. Six ameloblastomas (five follicular ameloblastomas and one plexiform ameloblastoma) and three malignant odontogenic tumors (one metastasizing ameloblastoma, one ameloblastic carcinoma, and one primary intraosseous odontogenic carcinoma) were investigated for CTNNB1 expression and CTNNB1 mutation. Immunohistochemically, all follicular ameloblastomas and one primary intraosseous odontogenic carcinoma exhibited focal and moderate nuclear/cytoplasmic expression of CTNNB1, whereas the plexiform ameloblastoma and the remaining two malignant odontogenic tumors had entirely membranous expression. CTNNB1 mutation at codon 40 of exon 3 was found in one of the six follicular ameloblastomas. The other five follicular ameloblastomas, the plexiform ameloblastoma, and the three malignant odontogenic tumors did not show mutation in exon 3 of CTNNB1. These findings further confirmed that CTNNB1 mutation is not frequent in ameloblastoma and malignant odontogenic tumors, although the abnormality of Wnt signaling may be associated with some of these tumors.

Desmoplastic ameloblastoma featuring basal cell ameloblastoma: a case report.

The desmoplastic ameloblastoma is a histological variant of ameloblastoma. The neoplastic epithelial islands seen in desmoplastic ameloblastoma are small and ameloblastic cells are rare. Basal cell ameloblastoma is also a rare variant of ameloblastoma, in which the tumor is composed of more primitive cells and has even fewer features of peripheral palisading. This report describes the case of a 17-year-old female with an ameloblastoma in the right anterior maxilla. Orthopantomography and computed tomography showed a well-defined lesion in the right maxilla. A partial maxillectomy for tumor resection was performed under general anesthesia. Histologically, ameloblastic tumor cells were seen with dense collagenous stroma and the tumor cells showed primarily basal cell variants of ameloblastoma. After 7 years of follow-up, clinical and radiographic examinations have revealed no evidences of recurrence.