Odontogenic Cysts turned Squamous Cell Carcinoma

Objectives: This case series aims to highlight that clinicians should be cognizant of the potential for odontogenic cysts to undergo malignant transformation, albeit rare. Odontogenic cysts are common lesions in the oral cavity, defined as cavities with odontogenic epithelium lining. While mostly benign, studies have shown that they have the potential to transform into malignant lesions - or Primary Intraosseous Carcinoma (PIC). They are rare central tumours that arise from odontogenic epithelium and may be associated with odontogenic cysts or other benign precursors. Diagnosis requires histological evidence of squamous cell carcinoma (SCC), absence of communication with overlying mucosa, and exclusion of metastasis from distant primary tumour. They most commonly involve the mandible, and typically present with pain and swelling.
Methods: Careful clinical and radiographic examination should always be performed. Patients may present with profound pain involving large areas of the jaw and/or paraesthesia – clinical features which should ring alarm bells. Suspicious radiographic signs include a large radiolucent lesion with mixed contents, ill-defined borders, and/or the destruction of cortical borders and surrounding structures. However, PIC may lack these features.
Results: The authors present 3 cases of malignant transformation of odontogenic cysts seen at the National Dental Centre, Singapore. Two cases arose from odontogenic keratocysts (OKC), one of which was a recurrence, and the third case was believed to have developed from a radicular cyst. Histopathological analysis of the enucleated specimens of all 3 cysts revealed squamous cell carcinoma (SCC). All three patients were subsequently worked up and treated with radical resection and neck dissection for PIC.
Conclusions: PIC often masquerade as an odontogenic cyst, posing a challenge for early diagnosis. It is thus prudent to submit the enucleated odontogenic cyst or pericoronal tissue for histopathological examination. If indicated, the patient should also be followed-up closely for recurrence.