Case Report A Rare Case of Intraductal Papilloma Arising from Minor Salivary Gland in the Floor of the Mouth Agnes Assao, 1 Silas Antonio Juvencio de Freitas Filho , 1 Luiz Antônio Simonetti Júnior, 2 and Denise Tostes Oliveira 1 1 Department of Surgery, Stomatology, Pathology and Radiology (Area of Pathology), Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil 2 Private Practice, Bauru, SP, Brazil Correspondence should be addressed to Denise Tostes Oliveira; denisetostes@usp.br Received 12 July 2020; Revised 9 August 2020; Accepted 16 August 2020; Published 25 August 2020 Academic Editor: Tanja Batinac Copyright © 2020 Agnes Assao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A 77-year-old woman with a rare oral intraductal papilloma arising from the minor salivary gland located on the floor of the mouth and causing the mucus retention is reported. Microscopically, the lesion was characterized by unicystic cavity exhibiting the lumen partially filled by papillary projections of the ductal epithelium with varying degree of oncocytic metaplasia. Based on the histopathological analysis, the differential diagnosis of oral intraductal papillomas and other ductal neoplasms of salivary origin are discussed. 1. Introduction The incidence of oral tumors arising from the salivary ductal glands, such as intraductal papillomas, is difficult to deter- mine because different terminology has been used for the denomination of the same lesion [1]. Specifically, oral intra- ductal papilloma in minor salivary glands is a benign solitary tumor characterized by intracystic papillary growth and duct-like structures that affect predominantly the lip and buccal mucosa of the 50-year-old or older patients [1–6]. The occurrence of intraductal papilloma on the floor of the mouth is extremely rare, and there are only a few cases reported in the English literature [4, 5]. We reported a rare intraductal papilloma that developed in the sublingual region involving a minor salivary duct gland and the differential diagnosis of this lesion with other ductal neoplasms of salivary origin are discussed. 2. Case Report A 77-year-old woman with a two months history of swelling and pain in the floor of the mouth was referred to the dentist. The patient was edentulous, and she has associated the lesion to the trauma of the complete dentures. The intraoral exam- ination revealed a unique soft nodule, tender to palpation, covered with clinically normal mucosa, well-circumscribed, sessile, located at the floor of the mouth, in the anterior left region of the mandible, measuring 1:1×0:9×0:7 cm. Upon extraoral examination, there were no palpable lymph nodes. Her medical history was noncontributory. The clinical hypothesis was of inflammatory fibrous hyperplasia or mucus retention cyst. An excisional biopsy was performed, and the surgical specimen was well defined, with no attach- ment to surrounding tissues. The histopathological analysis revealed a well- circumscribed unique cystic cavity arising from a minor sal- ivary duct gland characterized by papillary projections of the cuboidal/columnar mucous and oncocytic cells to the cysti- cally dilated ductal space and with no nuclear atypia or mitotic figures. The cystic lumen was partially filled by many branching papillary elements, consisting of thin strands of fibrovascular cores, surfaced by columnar cells and by a mucous fluid. The lesion is surrounded by a thick, fibrous tis- sue wall (Figures 1(a)–1(d)). Mucous secretory cells and mucous material exhibited positivity for periodic acid-Schiff staining (P.A.S.) (Figures 1(e) and 1(f)). Based on clinical Hindawi Case Reports in Pathology Volume 2020, Article ID 8882871, 3 pages https://doi.org/10.1155/2020/8882871