Notch4 overexpression in ameloblastoma correlates with the solid/multicystic phenotype.

OBJECTIVE: Notch signaling has been implicated in cell fate decisions during odontogenesis and tumorigenesis of some odontogenic neoplasms; however, its role in solid/multicystic (SA), unicystic (UA), and recurrent (RA) ameloblastoma remains unclear. The aim of this study was to determine Notch receptor and ligand expressions in these subtypes and to speculate on their significance. METHODS: Notch receptors (Notch1, 2, 3, 4) and ligands (Jagged1, 2, and Delta1) were examined immunohistochemically in SA (n = 23), UA (n = 22), and RA (n = 19). RESULTS: Notch4 overexpression in SA (n = 19/23; 82.6%) compared with UA (n = 1/22; 4.5%) or RA (n = 10/19; 52.6%) (P < .05) suggests positive correlation between Notch4 signaling and ameloblastomas with a solid/multicystic phenotype. Ligand (Jagged1 and Delta1) underexpression compared with their receptors (Notch1, 3, 4) (P < .05) and nonreactivity for Notch2 and Jagged2 in all 3 subsets suggests that ameloblastoma epithelium belongs to an earlier stage of differentiation (equivalent to inner enamel epithelium of developing tooth germ) before lineage commitment. CONCLUSION: Present findings suggest that Notch signaling molecules may play differing roles in the acquisition of different ameloblastoma phenotypes.

Analysis of the neoplastic nature and biological potential of sporadic and nevoid basal cell carcinoma syndrome-associated keratocystic odontogenic tumor.

BACKGROUND: Keratocystic odontogenic tumor (KCOT), also known as odontogenic keratocyst, is a benign cystic neoplasm, which may be associated with nevoid basal cell carcinoma syndrome (NBCCS) and if it does, will occur as multiple cystic lesions. KCOT is locally destructive despite its bland histological features. However, the neoplastic nature of KCOT is not well established. Heparanase is an endo-d-glucuronidase enzyme that specifically cleaves heparan sulfate (HS) and the increase of its level in tumors promotes invasion, angiogenesis, and metastasis. METHODS: To investigate the neoplastic character of KCOT, we studied the localization patterns of heparanase in KCOT, focusing on the differences between sporadic and NBCCS-associated KCOTs, by immunohistochemistry and in situ hybridization. To compare the expression pattern of these cysts with non-tumorous odontogenic developmental cyst, dentigerous cyst was included. RESULTS: All the odontogenic cysts showed positive immunoreaction for heparanase protein in various intensities. The expression pattern of heparanase gene corresponded to that of protein expression. Interestingly, intense gene and protein expressions were observed in KCOT associated with NBCCS compared with sporadic ones and dentigerous cyst. CONCLUSIONS: The results implied that heparanase expression may be correlated with the neoplastic properties of KCOT, particularly in NBCCS-associated cases.

An immunohistochemical evaluation of BMP-2, -4, osteopontin, osteocalcin and PCNA between ossifying fibromas of the jaws and peripheral cemento-ossifying fibromas on the gingiva.

The present study examined histological difference between ossifying fibromas (OF, n=5) and peripheral cemento-ossifying fibromas (PCOF, n=7). Bone morphogenetic proteins (BMP)-2 and -4, osteopontin (OPN), osteocalcin (OCN) and proliferating cell nuclear antigen (PCNA) were used for the immunohistochemical examinations. Oxytalan fibers present at the periodontal tissue were stained to determine the tumor cell origin. Many OFs showed high immunohistochemical reactions for BMP-2, -4 and OPN compared to those of PCOFs. PCNA index (IP) of OFs was significantly higher than that of PCOFs. All the PCOFs showed a high expression of oxytalan fibers. Only two OFs exhibited a small number of oxytalan fibers. These results suggest that PCOF has only little ability to form hard tissue and seems to be a reactive lesion. The expression of oxytalan fibers reveals that OF does not only originate from periodontal tissue.

Microcystic adnexal carcinoma with mandibular bone marrow involvement: a case report with immunohistochemistry.

Microcystic adnexal carcinoma is a rare, locally aggressive cutaneous neoplasm with a high probability of persistence locally but a low probability of metastasis. We report a case of a 69-year-old female patient with an indurated plaque at the mental region. Histologically, the tumor cells invaded the subcutaneous tissue and mandibular bone. The tumor consisted mainly of squamous and basaloid epithelial nests and cords embedded in a desmoplastic stroma. A few keratin-filled microcysts and ductal structures were also observed. Perineural encroachment was also noted but there was no mitosis, cytologic features of malignancy, or metastasis. The epithelial nests were positive to various cytokeratins except for CK20 and the lumina of the ductal structures were positive to carcinoembryonic antigen. Our results indicate that microcystic adnexal carcinoma consists of tumor cells capable of both follicular and eccrine differentiation. It is locally aggressive, extends far beyond its clinical presentation and may involve the bone. It may persist and remain asymptomatic for so many years without metastasis. A lifetime postsurgery monitoring is mandatory to ensure early and proper management.