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The location and the age of the patient are not consistent with a dermoid cyst. The region is, as is the slow growth and asymptomatic clinical presentation. The histology is not consistent with a dermoid cyst.
Dermoid cysts of the oral cavity are rare and constitute around 1.6% of all dermoid cysts, according to the original 1937 report on this condition by New and Erich. They are more common in the testes than in any other location, followed by the ovaries and the head and neck area. In the latter area, the floor of mouth is one of the more common areas of occurrence. This cyst is clinically classified into three types and is based on its relationship to the floor of mouth muscle and the geniohyoid and mylohyoid muscles. The more common presentation is above the geniohyoid and mylohyoid muscles, which are clinically visible in the floor of mouth as they push the tongue upward, leading to dysphagea, dyspnea and dysphonia. If it is between the geniohyoid and the mylohyoid muscle or below the mylohyoid muscle, it can create the appearance of a double chin. The third type is that in which the cyst is displaced laterally into the submandibular area. Dermoid cysts of floor of the mouth are rarely described in children under the age of 10. The majority of cases in the floor of mouth occur between the ages of 10 and 30; in cases in the ovaries, the age range is 15 to 40. Dermoid cysts above the geniohyoid muscle present as slowly enlarging large, round, raised and smooth-surfaced nodules. The nodule is usually painless unless it is infected. Infected cysts can drain through either intraoral or extraoral fistulas. The size of the lesion determines its interference with eating, speaking and swallowing. This cyst is classified histologically into two types: cystic structures with a lumen filled with keratin and a connective tissue wall with skin adnexa and true cystic teratomas with all three germ layers tissues such as the brain, bone, muscle, respiratory and gastrointestinal tissues. The oral dermoid cysts tend to be simple with skin adnexa in the wall. The true teratoma type cysts (more common in the ovary) are prone to malignant transformation more so than those in the floor of mouth. Treatment of choice is surgical removal via intra or extra oral approach, depending on where the cyst is located.