Extensive sublingual epidermoid cyst--diagnosis by immunohistological analysis and proof by podoplanin

We present the case of a surgically treated 39-year-old man with diagnosis of a giant sublingual internal epidermoid cyst. Usually, such dermoid or epidermoid cysts are caused by aberrant ectodermal tissues or by acquired aberrant epithelial tissues arising from the foetal period, or from trauma or surgery. The incidence of oral dermoid or epidermoid cysts is about 1.6%; most occur at the mouth floor but they nevertheless are very rare.

The patient presented with a history of progressive swelling of the sublingual region with dysphagia, progressive snoring during sleep and occasional shortness of breath. The suspected clinical diagnosis of a giant sublingual dermoid or epidermoid cyst was supported by the radiological finding after performing magnetic resonance imaging. The cyst was surgically removed under general anaesthesia through an intraoral approach. The immunohistological analysis of the specimen with a monoclonal antibody against podoplanin (D2-40) showed a positive reaction in the basal epithelial layer, exclusively in areas with secondary inflammation, but not in the remaining cyst wall.

Sublingually situated extensive epidermoid cysts are rare findings in the oral cavity. In such cases, surgical excision remains the only treatment. We demonstrated that cystic epithelia were normally not immunoreactive for D2-40 but strong immunoreactivity was observed in the basal epithelial cell layer, in areas of ruptured cyst wall associated with secondary inflammatory changes.