Squamous cell carcinoma in a maxillary odontogenic keratocyst

The epithelial lining of odontogenic cysts (OC) can undergo simple cystic expansion, keratinization, mucous prosoplasia, or dysplastic transformation. The most common neoplasms arising from the lining of odontogenic cysts are benign odontogenic tumors such as odontoma, calcifying odontogenic tumor, glandular odontogenic tumor, ameloblastic fibroma, calcifying epithelial odontogenic tumor, and adenomatoid odontogenic tumor.1,2 However, it is well known that the lining of an odontogenic cyst may transform into mucoepidermoid carcinoma or squamous cell carcinoma (SCCA).1,3,4 These 2 entities usually present with clinical and radiographic features similar to benign, expansile, central, odontogenic tumors or cysts of the jaws. Paresthesia and lymphadenopathy are uncommon. On radiologic examination, they appear similar to the cystic lesions from which they arose.1,3 Most of these entities are located in the mandibular third molar region.1 There are several classic articles regarding carcinomatous change in odontogenic cysts.1,3,5 These authors established the rarity of carcinomatous change in OCs, developed criteria for its diagnosis, and cataloged an initial database of cases. More recent reviews place the total number of reported cases of carcinomatous change in OCs at around 75.6-10 A conservative estimate from a review of the literature is that carcinomatous change, either mucoepidermoid or squamous, occurs in 1% or less of all OC’s.5,9 Eighty percent of SCCAs developing in an OC are diagnosed after age 40 years (mean age, 57 years; range, 4 to 90 years), with a 2:1 male:female ratio. Approximately 80% are found in the mandible.1,3,7,9-11 Metastases from these lesions are not common ( 20%), and most of the carcinomas are moderately to well differentiated.1,3,7,11-14 The 2-year survival from all central SCCAs is between 53% an 63%.1,7,9,15 Malignant change in odontogenic keratocysts (OKC) has infrequently been reported. In a review of the literature, only 15 reports of SCCA developing from OKCs were found.2,4,8-10,13,16-20,22-25 Most of these cases were treated in 2 phases, with enucleation or incisional biopsy as phase 1. When carcinoma was found initially, usually unexpectedly, further treatment included radical resection in most cases, neck dissection in half of the cases, and radiation or chemotherapy in one third of the cases.10,21 Frequently, the dysplastic change from the normal, cystic lining to dysplasia and then to frank SCCA could be traced along the length of the cyst wall.3,9,11,13,14,21 This is the gold standard for establishing the cyst epithelium as the primary site of the SCCA.1,4,9,10,13,14,21 Several cases documented perineural invasion and central necrosis in larger tumors.3,11,12,14,26,27 Maxillary sinus invasion occurred, with some lesions originating in the maxilla.3,28 The treatment for these lesions is determined by the extent of the carcinoma.5,8,10,29 If the carcinoma was in situ or wholly contained within the cyst wall, further surgical intervention should be deferred and the patient followed-up closely.6,9,14 If the margins of the tumor were positive or there was carcinoma in the surrounding bone, additional therapy is indicated.3,4,8-10,12,14,17,29 Some combination of resection, radiation therapy, and chemotherapy should be planned, with cervical lymph node dissection performed, if needed.1,4,8-10,12,15 Received from the University of Texas Health Science Center at San Antonio, San Antonio, TX. *Formerly, Resident, Department of Oral and Maxillofacial Surgery; Currently, Private Practice, Duluth, GA. †Assistant Professor, Department of Pathology. ‡Formerly, Professor and Senior Surgeon, Department of Oral and Maxillofacial Surgery; Currently, Professor, Director of Residency Education, Department of Oral and Maxillofacial Surgery, University of Kentucky, Lexington, KY. Address correspondence and reprint requests to Dr Makowski: North Georgia Oral Surgery and Dental Implants, Duluth Professional Park, Building G, Suite B, 3400 McClure Bridge Rd, Duluth, GA 30096. © 2001 American Association of Oral and Maxillofacial Surgeons 0278-2391/01/5901-0014$3.00/0 doi:10.1053/joms.2001.19297