Clear cell odontogenic carcinoma: A histopathologic mimicker of intraosseousmucoepidermoid carcinoma; a case report

Abstract

Background: Clear cell odontogenic carcinoma is a rare tumour, that is categorized among the malignant groups of odontogenic  tumours in the WHO classifications of odontogenic tumour from the 2005 and 2017 classification and to the recent 2022 classifications.  This is due to its aggressive clinical behaviour, metastasis to the lungs and lymph nodes and its tendency to recurrence. 

Case report: We  report a case of a 70-year-old female who presented with a painless mandibular swelling of 5 months duration. Examination revealed a  firm jaw swelling that measured 10 by 14 cm in the widest diameter, with hard and fixed submandibular lymph nodes. Radiographic  review showed a multilocular radiolucent lesion with hazy boarders. Incisional biopsy was done, and on histopathological examination,  sheets, strands, and islands of numerous clear cells with focal peripheral palisaded cells, necrotic foci, mitotic figures, abnormal mitosis,  and areas of keratinization were seen in a fibrous stroma. Special staining of the tissue with Periodic acid- Schiff (PAS) and mucicarmine  reagents showed positivity for PAS, but negative to mucicarmine.

Conclusion: This report emphasizes that patients with jaw lesions,  whose histopathologic report show numerous clear cells, should be evaluated further, at least with special stains, and   immunohistochemichal staining to exclude other clear cell lesions including central mucoepidermoid carcinoma, which has clear cells  (mucous cells) as a histopathological diagnostic feature.