A Rare Conjunctival/Caruncular Tumor, Squamous Cell Carcinoma with Mucinous Differentiation: A Case Report and Review of the Literature

Mucoepidermoid Carcinoma (MEC) is a very rare tumor for the conjunctiva defined in 1976 for this extraordinary localization. The term ‘MEC’ was revised as Adenosquamous Carcinoma (ASC) in the latest WHO classification of tumors of eye in 2018. Nevertheless, neither MEC nor ASC correctly reflected the histopathological features found in the vast majority of these conjunctival tumors. Therefore Squamous Cell Carcinoma (SCC) with mucinous differentiation was suggested as an alternative term for such tumors. Our case located in the caruncle had characteristic histopathological features completely representing SCC with mucinous differentiation. The caruncular localization is extremely rare for this type of conjunctival malignant tumor with only two case reports up to now. Furthermore, our case is also the first report in the literature presented as a polypoid benign-looking mass of which the main bulk was comprised of a ductal cyst and malignant tumor (SCC with mucinous differentiation) was coincidentally found very close, but completely unassociated with this ductal cyst.