Plunging epidermal cyst of the floor of the mouth in a young child

Abstract Epidermal (epidermoid) cysts are considered rare lesions in the oral cavity. They may be present early in life and are confined to one anatomical area but they are usually excised later in life when they eventually cause discomfort, difficulty in swallowing or cosmetic problems. In rare cases, however, they may rapidly enlarge in young individuals, in which case, early excisions of the cysts are required. A case of a large epidermoid cyst of the floor of the mouth extending extraorally in a 3‐year‐old boy is presented. It is likely that the cyst originated intraorally, which then enlarged and involved the submandibular and the neck region; therefore, the term ‘plunging epidermal cyst’ is used in this case. Ultrasonography and fine needle aspiration cytology suggested the diagnosis of either dermoid or epidermoid cyst. The lesion was surgically excised under general anaesthesia, and because of its large size, the surgery was done with combined intraoral and extraoral approach. The histopathology report of the lesion confirmed the diagnosis of epidermal cyst. One‐year follow‐up review revealed no recurrence of the cyst.