Sialadenoma Papilliferum of the Hard Palate: A Case Report

Abstract

Sialadenoma papilliferum (SP), which forms a group of ductal papillomas with inverted ductal papilloma and intraductal papilloma, is a rare benign papillary salivary gland tumor usually discovered as a whitecolored exophytic mass in the oral and maxillofacial region. Since the first 2 cases of SP in the parotid gland and the palate were reported in 1969, only 48 cases of the tumor have been reported in the Englishlanguage literature. The clinical appearances of the tumor in the oral cavity are similar to papilloma. However, the tumor consists of dilated salivary duct-like structures with papillary and exophytic proliferation of doubleor multiple-layered epithelium, as well as a concomitant overgrowth of surface squamous epithelium that exhibits verrucous acanthotic hyperplasia. Microscopic studies of SP were performed to better understand the cell origin of the tumor, and the findings suggested the lesion to originate from the intercalated duct cells. However, other studies reported that the tumor cells appeared to exhibit characteristic features of various cell types of the salivary gland duct apparatus. Furthermore, immunohistochemical analyses of SP showed the cell origin of the tumor to be the excretory ducts. However, the cell origin of the umor is still unclear. This report presents a new case of SP of the hard alate occurring in a 62-year-old man and includes a iscussion of the cell origin of the tumor.