[Immunohistochemical study of components of the basement membrane in odontogenic cysts]

Study of the relationship between mononuclear inflammatory infiltrate and Ki-67 and basement membrane and extracellular matrix protein expression in radicular cysts

AIM

To evaluate the relationship between mononuclear inflammatory infiltrate and the expression of a proliferative immunomarker (Ki-67) as well as to evaluate basement membrane and extracellular matrix proteins (laminin and collagen type IV) in radicular cysts and dentigerous cysts (DC).

METHODOLOGY

Immunohistochemical analyses were performed in heavily inflamed radicular cysts (HIRC), slightly inflamed radicular cysts (SIRC) and DC (n = 20) using Ki-67 (Dako(®) , 1 : 50), anticollagen type IV (DBS(®) , 1 : 40) and antilaminin (DBS(®) , 1 : 20). The data were analysed using anova/Tukey's test (Ki-67) and Kruskal-Wallis/Dunn's test (collagen type IV and laminin) (P < 0.05).

RESULTS

The immunoexpression of Ki-67 was significantly greater in the SIRC group compared with the HIRC and DC (P = 0.0040). Likewise, the immunoexpression of collagen type IV in the basement membrane of the SIRC group was significantly more continuous (P = 0.0475) than in the HIRC group. DC had significantly less collagen type IV in extracellular matrix immunoexpression than HIRC and SIRC (P = 0.0246). Laminin was absent in the basement membrane in the SIRC and DC groups, and the extracellular matrix of the HIRC was weak and punctate.

CONCLUSION

The presence of inflammatory factors in the radicular cyst wall modified the expression of proliferation factors in the epithelial lining and the expression of collagen type IV and laminin in the basement membrane, but did not modify extracellular matrix behaviour in radicular cysts.

Odontogenic keratocysts/keratocystic odontogenic tumours: biological characteristics, clinical manifestation and treatment

BACKGROUND

Odontogenic keratocysts (OKCs) now reclassified as Keratocystic odontogenic tumours (KCOTs) are a clinical entity with a characteristic microscopic picture, kinetic growth and biological behaviour. They arise from the proliferation of the epithelial dental lamina in both maxilla and mandible and occur in patients of all ages. 70-80% of keratocysts are found in the mandible commonly in the angle between the jaw and mandibular branch and maxillary region of the third molar. The cysts are long latent, often symptomless and may attain remarkable dimensions without significant deformation of the jaw bones. They are often found during routine dental X-ray examination. Compared to other types of jaw cyst, odontogenic cysts have a striking tendency to rapid growth and re-occurrence.

AIMS

This review focuses on the biological characteristics, clinical behaviour and treatment of KCOTs.

METHODS

The databases searched were the PubMed interface of MEDLINE and LILACS.

RESULTS AND CONCLUSIONS

Ondontogenic keratinocysts are not currently a diagnostic problem. Orthopantomograms which are today ordinary tools of dental investigation enable diagnosis of clinically asymptomatic cystic lesions. The problem remains the optimal therapeutic approach to reduce the still high likelihood of postoperative recurrence. There is no complete consensus on the ideal operating procedure but cystectomy with delayed extirpation is favoured. An open question also remains the timeliness of screening for postoperative recurrences. Given that the first clinical manifestation of Nevoid Basal Cell Carcioma Syndome (NBCCS) may be lesions of this type, routine histopathological classification supplemented by analysis of immunophenotype should be done. Patients with proven sporadic and especially syndromic OKC should be long term screened. In patients with NBCC preventive X ray examination is recommended only once a year.

Immunolocalisation of laminin-1 in keratocystic odontogenic tumors

Keratocystic odontogenic tumors (KOTs) are distinct odontogenic lesions frequently affecting the jawbones. They may be associated with nevoid basal cell carcinoma syndrome (NBCCS), and may exhibit disorders involving the extracellular matrix. The aim of this study was to investigate the immunolocalisation of laminin-1 in 20 cases of KOTs in order to contribute to the characterization of this protein, which is little studied in odontogenic tumors. Our results showed laminin-1 in all 20 KOTs studied; its labelling intensity was weak in three cases (15%), moderate in five (25%) and strong in 12 cases (60%). Laminin-1 immunolocalisation was predominantly continuous in 18 (90%) KOTs, including areas of acanthosis, subepithelial split and epithelial buds. Weak immunolabelling was observed in regions exhibiting an inflammatory process, especially in the case of intense inflammation. These findings suggest that laminin-1 does not participate in biological processes such as cystic epithelium-cystic wall separation or the formation of epithelial islands in KOTs. Furthermore, the discontinuous and weak labelling of this protein in the basement membrane of these tumors is probably a consequence of the inflammatory process in the tumor stroma.

Characterization and management of the keratocystic odontogenic tumor in relation to its histopathological and biological features

Keratocystic odontogenic tumor (KCOT), formerly referred to as odontogenic keratocyst, is a benign neoplasm of odontogenic origin which may present an aggressive and infiltrative behavior leading to high recurrence rates. A review of the various treatment modalities, ranging from simple enucleation to radical surgery is portrayed in relation to clinical, radiological, histopathological and molecular features. Although prognostic factors based on clinico-pathologic and immunohistochemical findings for determining the potential for recurrence of KCOT still remains unclear, its use for determining the potential for recurrence of KCOT after surgical treatment may become important to successfully manage this neoplasm's aggressive behavior. The key element for future management of KCOTs will probably be based on thorough knowledge of the biological basis of this tumor, thereby enabling a more tailored treatment approach.

Immunohistochemical expression of MMPs 1, 7, and 26 in syndrome and nonsyndrome odontogenic keratocysts

OBJECTIVE

The objective of this study was to analyze the expression of matrix metalloproteinases (MMPs) 1, 7, and 26 in odontogenic keratocysts (OKCs) associated with Gorlin syndrome (SOKCs) and nonsyndrome OKCs (NSOKCs).

STUDY DESIGN

Twenty-one SOKCs and 20 NSOKCs were evaluated for epithelial expression of MMP-1, MMP-7, and MMP-26 and for mesenchymal expression of MMP-1 by immunohistochemistry.

RESULTS

Strong epithelial positivity to MMP-1 was observed in 76% of SOKCs and in 15% of NSOKCs (P < .05). Strong mesenchymal immunoreactivity to MMP-1 was observed in 38% of SOKCs and in 20% of NSOKCs (P > .05). Epithelial immunoreactivity to MMP-7 was strongly positive in 67% of SOKCs and in 40% of NSOKCs (P > .05). For MMP-26, strong positivity was found in 62% of SOKCs, in contrast to 35% of NSOKCs (P > .05).

CONCLUSION

MMPs-1, -7 and -26 may play important roles in the biology of OKCs. Furthermore, the presence of these proteases at higher levels in SOKCs may help to explain increased OKC aggressiveness associated with nevoid basal cell carcinoma syndrome.

Immunohistochemical analysis of the biological potential of odontogenic keratocysts

BACKGROUND

The aim of this study was to analyse the usefulness of detecting important apoptosis and proliferation markers in assessing the biological potential of odontogenic keratocysts (OKC) and thus selecting the optimal diagnostic algorithm for these lesions.

METHODS

Indirect immunohistochemistry and relevant statistical methods were used for analysis of formalin-fixed and paraffin-embedded samples from 98 patients.

RESULTS

Nevoid basal cell carcinoma syndrome (NBCCS) keratocysts were characterized by higher expression of Bcl-2, p27Kip1 and c-erbB-2 as well as by lower proliferative activity measured by Ki-67 in basal cell epithelium and by a lower inflammatory response in comparison with sporadic keratocysts. Dentigerous, radicular and non-specified odontogenic cysts differed from both NBCCS and sporadic keratocysts in a wide spectrum of apoptosis and/or cell cycle-related protein expressions, higher proliferation in the basal cell layer, and vice versa, lower proliferation in the suprabasal cell layer.

CONCLUSIONS

The NBCCS keratocysts have a different immunophenotype from sporadic keratocysts and both types are distinguishable from dentigerous, radicular and non-specified odontogenic cysts. These findings confirm the separate biological potential of these lesions and the results of the immunohistochemical analysis have diagnostic and prognostic implications.

Immunohistochemical assessment of extracellular matrix components in syndrome and non-syndrome odontogenic keratocysts

OBJECTIVE

Investigate the immunohistochemical distribution of fibronectin, tenascin, laminin and collagen IV in syndrome (SOKC) and non-syndrome odontogenic keratocysts (NSOKC).

MATERIALS AND METHODS

Ten cases of SOKC and five of NSOKC were selected and streptoavidin-biotin technique was applied. The specimens were analyzed taking into account the following evaluation parameters: presence, continuity and thickness in the basement membrane and intensity, distribution and association with inflammatory cells in the cyst wall.

RESULTS

Differences could be detected regarding tenascin, fibronectin and collagen IV between the SOKC and NSOKC. Tenascin was present in all cases along the basement membrane in SOKC and in five cases of NSOKC predominated negative areas. Furthermore, tenascin distribution was focal in the cyst wall in SOKC whereas in NSOKC it was diffuse. Concerning fibronectin, it was detected as a discontinuous band when present in SOCK and as a continuous band in NSOKC. Collagen IV was not present in the majority of the cases in SOKC. Negative areas for laminin predominated in the basement membrane in both groups.

CONCLUSIONS

These findings show differences between the immunohistochemical expression of tenascin, fibronectin and collagen IV which might indicate a more aggressive biological behavior of SOKC as compared with NSOKC.

Tenascin and fibronectin expression in odontogenic cysts

BACKGROUND

Odontogenic cysts (OCs) present distinct evolution and clinical behavior. This study was performed in order to investigate if some components of the extracellular matrix (ECM) may drive these differences.

METHODS

Thirty OCs were selected: 10 radicular cysts (RCs), 10 dentigerous cysts (DCs), 10 non-syndrome odontogenic keratocysts (OKCs) and they were immunohistochemically analyzed to verify the expression pattern of tenascin and fibronectin.

RESULTS

Tenascin immunostaining was mainly intense as a thick band deep to the epithelial-mesenchymal interface in both RCs and OKCs. The intense tenascin immunoexpression observed in the RCs was usually associated with inflammation. An intense fibronectin reactivity was observed in the basement membrane region and at the cystic wall of OKCs.

CONCLUSIONS

Our results demonstrate differences between the expression of ECM proteins in the OCs studied. The higher tenascin and fibronectin expression in the capsule of OKCs suggests marked instability in the cystic structure and may contribute to its aggressive behavior.

Molecular Analysis to Demonstrate That Odontogenic Keratocysts Are Neoplastic

Context.—Odontogenic keratocysts (OKCs) are unique odontogenic lesions that have the potential to behave aggressively, that can recur, and that can be associated with the nevoid basal cell carcinoma syndrome. Whether they are developmental or neoplastic continues to be debated.

Objectives.—To identify loss of heterozygosity of tumor suppressor genes in OKCs and to suggest a pathogenetic origin for these lesions.

Design.—We examined 10 OKCs for loss of heterozygosity of tumor suppressor genes, using a microdissection and semiquantitative genotyping analysis. The genes analyzed included 10 common tumor suppressor genes, as well as the PTCH gene, which is mutated in nevoid basal cell carcinoma syndrome.

Results.—Loss of heterozygosity was seen in 7 of 10 cases, with a frequency between 11% and 80% of the genes studied. The genes that exhibited the most frequent allelic losses were p16, p53, PTCH, and MCC (75%, 66%, 60%, and 60%, respectively). Daughter cysts were associated with a higher frequency of allelic loss (P = .02), but epithelial budding was not.

Conclusions.—Our study indicates that a significant number of OKCs show clonal loss of heterozygosity of common tumor suppressor genes. The finding of clonal deletion mutations of genomic DNA in these cysts supports the hypothesis that they are neoplastic rather than developmental in origin.