Tehran University of Medical Sciences Journal of Craniomaxillofacial Research 2345-5489 4 1 2017 05 16 313 318 EN Jyotsna Galinde Professor, Department of oral and Maxillofacial Surgery, MGM Dental College & Hospital, Mumbai, India. Suraj Arjun Ahuja Resident, Department of oral and Maxillofacial Surgery, MGM Dental College & Hospital, Mumbai, India. 2017 05 16 2017 05 16 The occurrence of epidermoid and dermoid cysts in the oral cavity is extremely rare accounting 0.01% of all cysts. In our case report we hereby present a large epidermoid cyst in the floor of mouth imitating a plunging ranula. A 26-year-old female reported to us with a complaint of a swelling below the tongue since 2 year. On examination there was a swelling in the left side of the floor of the mouth, with anextra oral component in the submental area, the patient underwent surgical removal of the mass under local anaesthesia. Diagnosis of an epidermoid cyst was confirmed by the histopathological report. https://jcr.tums.ac.ir/index.php/jcr/article/view/146 https://jcr.tums.ac.ir/index.php/jcr/article/download/146/165