THIEME 1 Case Report Understanding Lateral Periodontal Cyst: A Case Report Monica Roy Chandel 1 Kundendu Arya Bishen 2 Nikit Agrawal 3 Himanshu Singh 4 1 Department of Oral and Maxillofacial Surgery, Index Institute of Dental Sciences, Malwanchal University, Indore, Madhya Pradesh, India 2 Department of Oral Pathology and Microbiology, Index Institute of Dental Sciences, Malwanchal University, Indore, Madhya Pradesh, India 3 Department of Oral and Maxillofacial surgery, Index Institute of Dental Sciences, Malwanchal University, Indore, Madhya Pradesh, India 4 Department of Oral Pathology and Microbiology, Index Institute of Dental Sciences, Malwanchal University, Indore, Madhya Pradesh, India received April 30, 2019 accepted May 20, 2019 Address for correspondence Kundendu A. Bishen, MDS, PhD, Department of Oral Pathology & Microbiology, Index Institute of Dental Sciences, Malwanchal University, Indore 452016, Madhya Pradesh, India (e-mail: kundenduarya@gmail.com). Lateral periodontal cysts (LPCs) are developmental in origin and are typically seen in the canine-premolar area in the mandible and less commonly in the maxilla. Reported rate of incidence of LPCs is less than 1%, and LPCs represent only 0.8% of entire central cysts of the maxillary bone. Despite its unique clinical and radiological presentation, it is finally diagnosed due to its unique histological characteristics. Here, we present one case with characteristic findings. The routine hematoxylin and eosin–stained sections revealed reduced enamel epithelium-like cystic lining that is made of thin, nonkera- tinized stratified squamous epithelium along with some epithelial plaques. The clini- cal-radio-pathological correlation affirmed the diagnosis of LPC. The pathogenesis of LPC has been discussed. Abstract Keywords ► lateral periodontal cyst ► pathogenesis of later- al periodontal cyst DOI https://doi.org/ 10.1055/s-0039-1693093 ISSN 2321-1482. ©2019 Bhojia Dental College and Hospital affiliated to Himachal Pradesh University Introduction Lateral periodontal cyst (LPC) is a rare and strange form of developmental odontogenic cyst. 1 Mandibular premolar area appears to be the most common location for LPCs, but presence of this cyst on various other sites is also report- ed. 2 LPCs appear to arise in intimate association with root surface (lateral) of erupted tooth. 3 Among developmental odontogenic cysts, the incidence of LPC is quiet low. The mean age of occurrence is 52 years with predilection for occurrence in age ranges from fifth to seventh decades and no predilection for race or sex. 4 Histopathologically, LPCs are classified under developmental cysts with lumen lin- ing showing thin, nonkeratinized epithelium that is mostly one to five cell layers thick—resembling reduced enamel epithelium. The epithelial lining illustrates focal thicken- ings or plaques where clear glycogen containing epithelial cells are seen. The connective tissue underlying to the epi- thelium exhibits zone of hyalinization. 5 Radiographically, a well-delineated ovoid or round radiolucent area with a sclerotic margin and maximum diameter of 1 cm is seen on lateral surface of root of teeth. The multicystic variant of LPC is known as botryoid odontogenic cyst (BOC) due to resemblance of the macroscopic and microscopic features with “bunch of grapes.” Case Presentation A male patient, aged 50 years, visited to a dental practitioner with a chief complaint of swelling on cheek area and pain in area of the right lower back teeth. Clinical inspection revealed a well-circumscribed and a well-defined ovoid swelling of size 2 cm × 1 cm on the lower right canine to premolar region (►Fig. 1). The swelling was nontender in nature, and there was absence of any pulsations. Clinically the teeth were non- carious and vital. Radiographic examination affirmed a well-defined radiolucency (pear-shaped) in the upper and middle third of 43 and 44 with a sclerotic border. Also, interdental bone loss was clearly evident in between them (►Fig. 2). Based on aforementioned findings, a diagnosis of LPC was given clinicoradiologically. Dent J Adv Stud Published online: 29.08.2019