U n ive rs ity J D en t S c ie 20 15 ; 1( 1) :1 -2 Abstract Trichilemmal cyst of oral cavity is a rare entity. Usually it is seen in scalp or other areas of body where hair follicle concentration is high. These cysts are derived from the outer root sheath or trichilemma of the hair follicle where keratinization occurs. Trichilemmal cyst keratin stains with antikeratin antibodies derived from human hair. This staining is a confirmatory investigation of this cyst. We are reporting this case for its rarity of occurrence. To our knowledge only three cases of this disease have been so far reported. 1 2 3 4 Zarin Fatima , Shadab M. Rizvi , Sayeedul H Arif and Syed S. Ahmed , 1 Ex. Resident, Department of Periodontics and Community Dentistry 4 Associate Professor and Chairman, Professor Department of Oral and Maxillofacial 3 Surgery, Associate Professor, Department of Pathology, JN Medical College, 4 Professor, Dr. Ziauddin Ahmed Dental College, Aligarh Muslim University, Aligarh Key words : Trichilemmal cyst, Antikeratin antibody, Pilar cyst Conflict of interest : Not declared Introduction Trichilemmal cyst, which is also known as pilar cyst or isthmus catagen cyst, is usually seen as a scalp lesion and its features are similar to epidermoid cyst. The lesion presents as a firm, smooth, round nodule without a visible punctum. Their size and shape and may be solitary or multiple. These cysts are commonly seen in head and neck region1,2 and arise preferably in those areas where hair follicle concentration is high and thus common among the subcutaneous cysts of the scalp. Trichilemmal cyst of oral cavity is very rare entity.. We are reporting this case due to its rarity and to document one more case in the literature. Case report A 21 year old male patient reported to the department of oral and maxillofacial surgery of our institute with the chief complaint of swelling in the mucosal side of right cheek for the past 2 years. The past history revealed that about two years back it was a small nodule in the right cheek which gradually increased in size. Although, it was painless, but growing slowly and causing cosmetic disfigurement and he attended the hospital for his esthetic concerns only. Extra-orally there was a diffuse round swelling measuring 2.5 x 2. 0 cm in size and same was palpable and visible extra-orally. The overlying mucosa and skin was smooth and normal in colour. Extra-oral radiographic findings were insignificant. A differential diagnosis of the lesion was and was provisionally diagnosed as fibroma of cheek and biopsy was planned under local anesthesia. For biopsy trans-oral route was opted due to esthetic reasons and incision was given in cheek mucosa to expose the nodule. Just after exposure and dissection of underlying tissue a fibrous capsule was visible. The capsule was dissected out and the whole content could be removed in a single light yellow mass, preserved in 10% formalin solution and sent for histopathological examination. Fig.1 Enucleated mass The wound was closed using 3.0 black silk by interrupted sutures. Healing was uneventful and sutures were removed on 5th postoperative day. Fig 2 - Cyst lined by stratified squamous epithelium with cystic spaces filled with keratin (10X) TRICHILEMMAL CYST OF ORAL CAVITY- CASE REPORT OF RARE ORAL ENTITY Journal of D ent al Sci ence U niversit y Review Article 66