Acta Otorrinolaringol Esp. 2013;64(4):306---309 www.elsevier.es/otorrino CASE STUDY Undifferentiated Carcinoma in Oncocytic Schneiderian Papilloma. A Rarity  Carcinoma indiferenciado en el papiloma oncocítico Schneideriano. Una rareza Pradeep Devadoss, ∗ Pedamally Manodh, Dayashankar Prabhu Shankar, Titus Kuttappan Thomas, Ravanasamudram Sundaram Neelakandan, Shobhit Rastogi Department of Oral & Maxillofacial Surgery, Meenakshi Ammal Dental College & Hospital, Alapakkam Main Road, Maduravoyal, Tamil Nadu, India Received 28 October 2011; accepted 13 December 2011 The term Schneiderian mucosa refers to the ectodermally derived lining of the nasal cavity and paranasal sinuses, com- posed generally of stratified ciliated columnar cells, loose abundant lamina propria, and minor salivary glands and their ducts. This unique mucosa may give rise to three distinct histomorphologic papillomas collectively called Schneide- rian papillomas. Hyams 1 has described these variants and categorized them as inverted, fungiform (exophytic, squa- mous) and oncocytic Schneiderian papilloma (cylindrical cell papilloma) based on their pattern of growth. Schneide- rian papillomas are uncommon, representing only 0.4%---4.7% of all sinonasal tumors. 2---4 Oncocytic Schneiderian papillo- mas are the rarest of the three morphological variants, accounting for only 3 per cent of all sinonasal papillomas. 3,4 Sinonasal papillomas have a small but distinct risk of malignant transformation. 5---10 Here, we report a case of undifferentiated carcinoma arising from oncocytic Schneiderian papilloma (OSP). To the best of our knowledge, the current patient is the fourth reported case of undiffer- entiated carcinoma arising in OSP in English literature.  Please cite this article as: Devadoss P, et al. Carcinoma indifer- enciado en el papiloma oncocítico Schneideriano. Una rareza. Acta Otorrinolaringol Esp. 2013;64:306---309. ∗ Corresponding author. E-mail address: dr pradeepds@yahoo.co.in (P. Devadoss). Case Report A 75-year-old lady presented with recurrent unilateral epis- taxis associated with progressive nasal blockage and right nasal purulent discharge with a foul odor of eight months duration. Clinical examination revealed a fleshy, polypoid mass arising from right lateral nasal mucosa obstructing the right nostril with diffuse swelling on the right side of face. Computed tomography confirmed the presence of soft tis- sue mass in the right lateral nasal cavity and opacification of maxillary and frontal and ethmoid sinuses (Fig. 1). No bony destruction was noted. Incisional biopsy through Caldwell Luc approach revealed it to be a case of OSP. The patient was subjected to general anaesthetia under nasoendotracheal intubation on left side for lateral rhinotomy with medial maxillectomy and frontoethmoi- dospenoidectomy. Intraoperatively, multiple polypoidal masses were found involving right lateral wall of the nasal cavity with extension into the all paranasal sinuses on the right side. The entire tumor mass was delivered en masse and subjected to histopathological examination after staining with hematoxylin---eosin. Other confirmatory tests like immunohistochemical analysis were not carried out for lack of sufficient resources. The patient had an unevent- ful postoperative recovery. She was last seen six months post operatively and there was no recurrence noted. The patient is being followed periodically for any evidence of 2173-5735/$ – see front matter © 2011 Elsevier España, S.L. All rights reserved.