Nevoid Basal Cell Carcinoma Syndrome: A Long-Term Study in a Family

A comparative immunohistochemical analysis of cortactin in orthokeratinized odontogenic cyst (OOC), sporadic odontogenic keratocyst (OKC), and syndromic OKC

OBJECTIVES

To evaluate and compare the immunohistochemical expression of cortactin in the epithelial lining of orthokeratinized odontogenic cyst (OOC), sporadic odontogenic keratocyst (OKC), and syndromic OKC.

METHODS

Formalin-fixed paraffin-embedded tissue blocks of histopathologically diagnosed cases of OOC, OKC, syndromic OKC, normal buccal mucosa (NBM), and oral squamous cell carcinoma (OSCC) were examined for immunohistochemical expression of cortactin. Clear brown cytoplasmic and membranous staining was considered positive.

RESULTS

A statistically significant difference was observed between OOC and syndromic OKC (p<0.001), as well as between sporadic OKC and syndromic OKC (p<0.001). Although not statistically significant, the expression of cortactin was slightly higher in the basal layer of NBM (mean=0.47), OOC (mean=0.27), sporadic OKC (mean=0.47) syndromic OKC (mean=1.53), and OSCC (mean=0.67) than in the parabasal layers of NBM (mean=0.27), OOC (mean=0.20), sporadic OKC (mean=0.47), syndromic OKC (mean=1.27), and OSCC (mean=0.60).

CONCLUSION

The expression of cortactin in the basal layer may suggest the formation of invadopodia in the basal layer where the invasion mechanism occurs. This finding is further supported by the higher localization of cortactin in areas of epithelial budding and daughter cysts in syndromic OKC, thereby reaffirming its possible association with recurrence.

Absence of BRAFV600E immunohistochemical expression in sporadic odontogenic keratocyst, syndromic odontogenic keratocyst and orthokeratinized odontogenic cyst

BACKGROUND

Odontogenic keratocyst (OKC) is a unique developmental odontogenic cyst that has the potential to behave aggressively and is associated with the nevoid basal cell carcinoma syndrome. Orthokeratinized odontogenic cyst (OOC) is a distinct, uncommon odontogenic cyst. It significantly differs from OKC not only in its epithelial lining but also in proliferating kinetics, clinical, immunohistochemical and biological behaviour. BRAF gene located on chromosome 7q34 encodes a cytoplasmic serine-threonine kinase. Various immunohistochemical studies have been conducted to express the BRAFV600E gene mutation in various odontogenic cyst and tumours with varying results. The present study was conducted to evaluate the possible role of BRAFV600E in the pathogenesis of sporadic OKC, syndromic OKC and OOC by immunohistochemistry.

METHODS

Formalin-fixed paraffin-embedded (FFPE) tissue blocks of 15 diagnosed cases each of sporadic OKC, syndromic OKC and OOC were retrieved from the archives of Department of Oral Pathology and subjected to immunohistochemical staining for the detection of BRAFV600E mutation using a novel rabbit monoclonal antibody clone RM8.

RESULTS

Immunohistochemical analysis showed complete absence of BRAFV600E mutation in all cases of sporadic OKC, syndromic OKC and OOC.

CONCLUSION

The negative immunohistochemical expression of BRAFV600E in sporadic OKC, syndromic OKC and OOC suggests that BRAFV600E plays no role in the pathogenesis of sporadic OKC, syndromic OKC and OOC.