Primordial Odontogenic Tumor in Anterior Mandible: A Case Image.

The primordial odontogenic tumor (POT) is a rare mixed odontogenic tumor believed to develop during early odontogenesis. It is composed of a fibromyxoid stroma with proliferation of mesenchymal cells surrounded by a layer of columnar cells exhibiting reverse polarity and pale cytoplasm. This article presents a case of primordial odontogenic tumor in the anterior region of the mandible of a 10-year-old male Caucasian patient who presented with an expansive intraosseous lesion in the anterior portion of the mandible and a delay in tooth eruption, with a 1-year history of asymptomatic swelling. An incisional biopsy was performed and sent to an external pathology service that diagnosed as ameloblastoma. The clinician sent the paraffin block and hematoxylin/eosin (H&E) slides for diagnosis review to the University of Sao Paulo, Oral Pathology Service. The H&E slides revealed an abundant myxoid cell-rich stroma containing a few islands of ameloblastic-like epithelium and areas of loosely arranged stellate/spindle-shaped cells resembling stellate reticulum. The odontogenic-like epithelium was also noted at the periphery of the specimen, as well as discrete areas of hyalinization. Cellular pleomorphism and mitotic figures were not observed, supporting the diagnosis of ameloblastic fibroma. The clinician proceeded with surgical excision and sent us the whole specimen. After reviewing the slides and discussing the case, the final diagnosis was primordial odontogenic tumor. This report is relevant to provide more information for clinicians and pathologists about this rare entity.