Expansile keratocystic odontogenic tumor in the maxilla: immunohistochemical studies and review of literature

Abstract

Keratocystic odontogenic tumors (KCOT) - previously termed odontogenic keratocysts (OKC) - are characterized by aggressive behavior and a high rate of recurrence. Histopathologically, the basal layer of KCOT shows a higher cell proliferation rate and increased expression of anti-apoptosis genes. Clinically, KCOT is frequently involved in the mandibular posterior region but is not common in the posterior maxilla. However, it should be noted that due to its expansive characteristics, KCOT involved near the maxillary sinus could easily expand to an enormous size and occupy the entire maxilla. To achieve total excision of these expanded cystic tumors in the maxilla, a more aggressive approach would be needed. In this report, we describe two cases of expansile KCOT involving the entire unilateral maxilla and maxillary sinus; they were completely excised using the Weber-Ferguson approach, showing no evidence of recurrence during the follow-up period of more than two years. In immunohistochemical analyses of the tumor specimens, p53 and p63 showed strong expression, and B-cell lymphoma 2 (BCL2) and MKI67 (Ki-67) showed moderate or weak expression, however, detection of BCL2-associated X protein (BAX) was almost negative. These data indicate that expansile KCOT possesses increased anti-apoptotic activity and cell proliferation rate but decreased apoptosis. These properties of KCOT may contribute to tumor enlargement, aggressive behavior, and high recurrence rate.

Importance of Different Modalities of Treatment For the Management of Keratocystic Odontogenic Tumour with Five year follow-up

“…So many authors have described different modalities. Since KCOT exhibits high recurrence rate 5-15% of all odontogenic cysts [12], the ultimate goal of treatment should be complete, adequate removal of the cyst. Treatment should be based on so many parameters such as extent, age, aggressiveness and size of the lesions.…”

Giant keratocystic odontogenic tumor: a challenging diagnosis

“…The epithelium of KCOT has decreased apoptotic activity, allowing the survival of genetically unstable cells. The higher epithelial proliferation rate, and the inhibition of apoptosis of the damaged cells, are important steps in tumor development 7. KCOT exhibits unique growth and biological behavior compared to common cysts, wherein the growth is due to the active proliferation of the epithelial lining.…”

“…These are designated as a consistent finding in Gorlin syndrome 5. Based on their biological behavior, neoplastic features, and recent research in genetics, the WHO in 2005 reclassified OKC as KCOT, which is now defined as a benign unicystic or multicystic, intraosseous tumor of odontogenic origin, with a characteristic lining of parakeratinized stratified squamous epithelium and potential for aggressive, infiltrative behavior 6 , 7. KCOT is a benign developmental intraosseous neoplasm of the jaws arising from cell rests of the dental lamina (the oral epithelial lining of the developing tooth follicle) and an extension of basal cells of overlying oral epithelium 1…”

“…KCOT is predominant in males; it occurs mainly in the second and third decade of life, and is most frequently found in the posterior body of the mandible and ascending ramus 7. In the maxilla, the canine region is the most common location for KCOT, and it is quite unusual for it to occur in the maxillary sinus.…”

“…It could easily expand to an enormous size occupying the entire maxilla. Maxillary sinus is a less dense structure, thus allowing the rapid growth of the lesion 7. Such an extensive lesion involving an unusual site often presents with diagnostic and, therefore, therapeutic challenges.…”