Multinucleated giant cells appear in a variety forms in different types of oral lesion. However, their nature is still not well understood. Thus, to address this issue, the immunohistochemical characteristics of inflammatory giant cells (Langhans’ giant cells in lesions of tuberculosis and foreign body giant cells in odontogenic keratocysts and squamous cell carcinomas) and tumor giant cells in central giant cell granulomas were compared with those of osteoclasts, the normal giant cell, using a panel of macrophage and osteoclast marker antibodies, such as calcitonin receptor (CT-R), c-Src, Cathepsin K (Cath-K), CD14, RANK, and c-fms. The foreign body giant cells around cholesterol clefts in inflamed odontogenic keratocysts revealed more macrophage-like characteristics than the foreign body giant cells resorbing keratin pearls in squamous cell carcinomas. As such, both cases of foreign body giant cell exhibited immunoreactivity for the macrophage markers, such as CD14, RANK, and c-fms, yet only the latter case exhibited immunoreactivity for the osteoclast markers, such as CT-R and c-Src. Moreover, both cases of foreign body giant cells were positive for TRAP activity, yet negative for Cathepsin K activity. In contrast, the other inflammatory giant cells, Langhans’ giant cells, exhibited immunoreactivity for both the macrophage and osteoclast markers, yet were negative for TRAP activity. Meanwhile, the giant cells in the central giant cell granulomas reacted positively to both the macrophage and osteoclast markers, and were also positive for TRAP activity. Accordingly, these findings suggest that the immunoprofiles of giant cells in oral lesions vary according to the nature of the lesion, despite shared osteoclast and macrophage characteristics. Furthermore, the giant cells in tumorous lesions closely associated with bony destruction revealed more osteoclastic characteristics and their enzyme components were different according to the nature of the lesion

Socket sclerosis can be an obstacle for orthodontic space closure, however, the precise histomorphogenetic mechanism has not been elucidated up to date. A 73 years old female complained of dull pain on palpation in the extraction site of the left maxillary first molar, and uncomfortable to use her complete denture. In panoramic X-ray view the socket sclerosis was clearly demarcated as a radiopaque outline of extracted root. In histological examination the socket sclerosis showed the basophilic deposition of cementum- like materials in the peripheral rim of trabecular bones instead of eosinophilic osteoid materials for intramembranous ossification. In the immunohistochemical staining for osteogenetic proteins, BMP-2 was strongly positive in the peripheral rim of trabecular bone, in which RANKL and osteoprotegerin were also consistently positive. Particularly, versican, a marker of cementum was also positive in the peripheral rim of the trabecular bone. Therefore, it is presumed that the trabecular bones of socket sclerosis were hypermineralized by cementoid ossification, producing cementum-like materials by osteoblasts/cementoblasts derived from the previous periodontium.

Metastatic tumors in oral cavity are rare, where their prognoses are considered to be extremely poor. Unless recognizing its primary origin, pathologic diagnoses for metastatic cancer have been troublesome for oral pathologists. This retrograde analysis was aimed at providing practical suggestion for the diagnoses of metastatic cancers to oral and maxillofacial region. We reviewed 20 patients diagnosed as metastatic cancers to oral cavity from 1991 to 2007. The patients were classified according to their clinical and histologic findings. We also reviewed 19 patients of mucoepidermoid carcinoma and 16 patients of adenoid cystic carcinoma to compare with those of metastatic cancers. Immunohistochemical staining for CK 5/6, CK 17, TTF-1, CEA was performed for differential diagnosis. Histologically, 20 cases compromised 11 cases of adenocarcinoma, 5 cases of undifferentiated carcinoma, 3 cases of squamous cell carcinoma, and one papillary carcinoma. The lung was the most common site for primary site (5/20), followed by the breast (2/20). In metastatic adenocarcinoma, TTF-1 positive cases were one lung cancer and a rectal cancer, and carcinomas from breast and rectum showed CK5/6 positive reaction. CEA was expressed in gastric and rectal carcinomas. In 19 cases of mucoepidermoid carcinoma, 13 cases (68.4%) are CK5/6 (+). In 16 cases of adenoid cystic carcinoma, 11 cases (68.8%) showed the positive reaction for CK5/6. TTF-1 is an antibody to show high sensitivity and specificity for lung adenocarcinoma, therefore, TTF-1 is helpful to make a diagnosis of metastatic adenocarcinomas from lung. Adenocarcinomas originated from salivary glands show high CK5/6 expression, but metastatic adenocarcinomas, except of those from breast and rectum, show no CK5/6 expression, lending support that CK5/6 may be useful to differentiate metastatic adenocarcinomas from carcinomas of salivary gland origin.