Case Report Indian Journal of Pathology and Oncology, July-September 2016;3(3);522-525 522 Giant Plexiform Unicystic Ameloblastoma: A rare variant of Ameloblastoma Yashita Gupta 1,* , Mohd. Jafar Memon 2 , Nighat Hussain 3 , Renuka Gahine 4 1 Senior Resident, 3 Associate Professor, Dept. of Pathology & Laboratory Medicine, AIIMS, Raipur, 2 Assistant Professor, Pt. JNM Medical College, Raipur, 4 Professor & Head, Dept. of Pathology, Govt. Medical College, Rajnandgaon *Corresponding Author: Email: yashigupta@gmail.com Abstract Ameloblastoma is the most common clinically significant odontogenic tumor of the gnathic bones, characterized as a benign but persistent and locally aggressive neoplasm. According to the WHO, it presents in four forms: unicystic, multicystic, peripheral (within soft tissue), and desmoplastic, with the conventional solid intra-osseous type being the most common (86%). Microscopically, many subtypes or patterns have been described: follicular, plexiform, acanthomatous, papilliferous –keratotic (including so-called keratoameloblastoma), granular cell, desmoplastic, vascular, and with dentinoid induction (dentinoameloblastoma). This report describes a case of a giant unicystic ameloblastoma involving the left side of the mandible. Radiographically appearing as a unilocular radiolucency and non-dentigerous in nature. Histopathological analysis showed features of plexiform pattern of a unicystic ameloblastoma. Keywords: Ameloblastoma, Odontogenic neoplasm, Unicytic, Plexiform Access this article online Quick Response Code: Website: www.innovativepublication.com DOI: 10.5958/2394-6792.2016.00096.X Introduction Churchill first used the term ameloblastoma in 1934 [1] . Ameloblastoma, is derived from the English word “amel” which means enamel and the Greek word “blastos” which means the germ [2] . Ameloblastoma is defined as most common benign epithelial odontogenic tumor, which is slow growing, but locally aggressive, persistent, and frequently recurrent [3] . It accounts for about 1% of all oral tumors and about 9-11% of odontogenic tumors [4] . The majority of ameloblastomas occur in the posterior mandible, with a wide variety of radiographic and clinical presentations, each carrying treatment and prognostic implications. The tumor arises from the enamel organ or its progenitor cell lines [3] . Unicystic ameloblastoma (UA) is considered at best an in situ or superficially invasive form of ameloblastoma and accounts for 6% of reported cases of ameloblastoma [5] . UA is defined as variant of ameloblatoma in which there is de novo development of a cyst or neoplasm (ameloblastomatous) development in a pre-existing cyst [6] . We report a case of giant plexiform unicystic ameloblastoma which is a relatively rare variant of UA. Case Report A 22-year-old male patient presented with the chief complaint of left side progressively increasing facial swelling since 2 years. Swelling initially appeared in the left infraorbital region and gradually increased in size completely involving the left side of the face. Swelling was painless initially, but the patient now complains of mild persistent pain. The patient was prescribed antibiotics and ointments by a general practitioner multiple times in the last 2 years The swelling was roughly oval in shape with approximate size of 16 x 13 x 12.5 cm.The margins of the swelling were diffuse. The skin overlying the swelling was smooth with a scar mark in the centre due to local application of some ointment given by general practitioner (Fig. 1). Fig. 1: Diffuse large swelling involving the left side of the face On local examination, swelling was found to be firm to soft and temperature of overlying skin was slightly elevated. At angle of mandible expansion of the cortical plates was noted. Intraoral examination revealed a single swelling in retromolar area. Clinically provisional diagnosis of benign odontogenic lesion was made. Differential diagnosis of