Original ArticlesOlfactory Epithelial Hamartoma A New Subtype of Sinonasal HamartomaKossai, Myriam MD*,†; El Zein, Sophie MD*,†; Wassef, Michel MD*,†; Guichard, Jean-Pierre MD‡; Pouliquen, Christelle MD§; Herman, Philippe MD, PhD†,∥; Vérillaud, Benjamin MD, PhD∥; Classe, Marion MD*,†Author Information Departments of *Pathology ‡Neuroradiology ∥Otolaryngology, Head and Neck Surgery, Assistance Publique, Hopitaux de Paris, Lariboisière Hospital †Faculty of Medicine, Paris Diderot University §Department of Pathology, Assistance Publique, Hopitaux de Paris, Tenon Hospital, Paris France Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Michel Wassef, MD, Department of Pathology, Lariboisière Hospital, 2 rue Ambroise Paré, Cedex 10, Paris 75475, France (e-mail: [email protected]). The American Journal of Surgical Pathology: January 2018 - Volume 42 - Issue 1 - p 9-17 doi: 10.1097/PAS.0000000000000967 Buy Metrics Abstract Sinonasal epithelial hamartomas occurring in adults are classified as seromucinous hamartoma (SMH) or respiratory epithelial adenomatoid hamartoma (REAH). We describe herein a novel subtype of adult sinonasal hamartoma that contains olfactory epithelium, a histologic feature not previously reported in the literature. Our pathology department database was retrospectively searched for sinonasal hamartomas containing areas of olfactory epithelium. Six relevant cases (3 male and 3 female patients; age, 30 to 77 y) were retrieved, and available pathology slides and clinical and imaging data from patient charts were reviewed. Five of the lesions were unilateral solitary, polypoid, pedunculated masses, 38 to 80 mm in length, lodged in the nasal olfactory cleft. The sixth lesion was associated with bilateral nasal polyposis, and its precise localization was not known. All patients were treated by transnasal endoscopic surgery. None of the 3 patients who had received adequate follow-up evaluation exhibited recurrence. Histologically, all lesions resembled SMH or REAH, with areas of olfactory epithelium comprising olfactory receptors and sustentacular and basal cells. Olfactory epithelium was observed at the lesion surface or in invaginated gland-like structures, and it contained focal aggregates of filamentous cell processes. Some olfactory receptor cells or cell processes were also present in the seromucinous gland component of lesions. Olfactory receptor cells expressed CD56 (neural cell adhesion molecule), and the filamentous aggregates contained CD56, neurofilaments, and synaptophysin. Aside from SMH and REAH, we have described a third subtype of adult sinonasal hamartoma—olfactory epithelial hamartoma—which shares the benign character of the other 2. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.