Sclerosing Odontogenic Carcinoma: A Unique Odontogenic Carcinoma with Metastatic Potential.

Background: The recent World Health Organization (WHO) classification of odontogenic tumours defines Sclerosing Odontogenic Carcinoma (SOC) as a rare primary intraosseous carcinoma (PIOC) of the jaws. With the exception of one case, there have been no cases of SOC with metastatic disease. We report a unique case of SOC with neck node metastases, further expanding the clinical, radiological and histological spectrum of this rare intriguing tumour.

Methods: A 52-year-old female presented with a destructive radiolucent lesion of right mandible. Incisional biopsy was interpreted as desmoplastic ameloblastoma. The segmental mandibulectomy specimen was histologically consistent with SOC with positive anterior margin. Further resection with neck dissection revealed positive right levels IB and IIA nodes. Immunohistochemistry and Fluroscent In Situ Hybridization (FISH) were performed to confirm the diagnosis.

Results: The tumour was positive for CK5, p63, p40 and negative for CK19, CK20, CK7, SOX-10, S100, ER, PR, BRAFV600E, and EWSR1 gene rearrangements. Ki67 was 15%.

Conclusion: To avoid confusion with PIOC, a high grade squamous cell carcinoma of the jaws with poor prognosis, SOC may be best defined as a rare infiltrative and locally aggressive odontogenic carcinoma with metastatic potential but with a reasonably favourable outcome. SOC shares similar histologic features with many benign and malignant tumours. An appropriate panel of immunohistochemical markers, in conjunction with special stains and molecular studies can help refine the differential diagnosis. It appears that a Ki67 proliferation index of more than 10%, may pose a risk for nodal metastasis and may assist in planning the clinical management. To achieve lower rates of positive margins and tumour recurrence, a wider resection margin (more than a centimetre) is recommended.