LAUSR

We were interested to read the excellent and comprehensive article by Kennedy [1], reporting and reviewing the neuroepithelial structures (NESs) that are unique to oral soft tissues. The author’s literature analysis indicates that NESs were reported by Palazzolo et al. [2] and Cheng et al. [3] to be associated with the subepithelial nerve plexus of taste buds resembling the juxtaoral organ of Chievitz (JOOC). However, the nature of these structures has been studied with varying conclusions and remains controversial. Few pathologists are aware that this controversial entity was first described in a report of median rhomboid glossitis by Baughman [4], who conducted an anatomical cadaver study of the foramen cecum region of 184 tongues in 1971 and noted three specimens showing epithelial structures (ESs) with a consistent squamous appearance in the lamina propria. Providing a representative photomicrograph, he concluded that ESs represent a marked squamous metaplastic change of the serous (von Ebner’s) glands, and clearly pointed out that the presence of submucosal ESs can lead to a misdiagnosis of squamous cell carcinoma (SCC). Two years later, in a postmortem study of median rhomboid glossitis, van der Waal [5, 6] found various forms of ESs in 11 of 76 tongue specimens from individuals with a mean age of 60 years. These ESs showed no age or gender predilection. Serial sections showed that solid and cystic ESs apparently extended to the overlying lingual epithelium. He concluded that ESs might be a regular feature in the lamina propria of circumvallate papillae, resulting from squamous metaplasia of von Ebner’s glands. At that time, neither of the former authors referred to a neural background [4–6]. In his 1973 microanatomical analysis of the foramen cecum using 100 tongue specimens from cadavers, Soames [7] reported inflammation-associated simple squamous metaplasia of the superficial ducts of both mucous and serous posterior lingual glands. In the absence of any systematic studies, little is known about submucosal ESs in this location. Missing from Kennedy’s review was a case report by Val-Bernal et al. [8] (2006), describing ES under a diagnosis of subgemmal neurogenous plaques (SNPs) with pseudoepitheliomatous hyperplasia [1]. After reading the 2014 paper by Palazzolo et al. [2], Fonseca et al. [9] suggested the term “NESs associated with SNP”. Since the precise origin and nature of lingual ESs are still debatable, a variety of compound names have been adopted, including squamous metaplasia of the salivary gland ducts of serous von Ebner glands mimicking SCC [10], necrotizing sialometaplasia of von Ebner glands mimicking SCC [11], benign NESs associated with subepithelial nerve plexus of taste buds [12], “75 year old woman with a tongue mass” [13], and SNP in close proximity to bland squamous cell nests [14]. It has long been recognized that the posterior one-third of the tongue is replete with epithelial vestiges because of the complexity of the developmental pathway during embryogenesis. On the basis of our literature review, we would now consider so-called lingual NESs to be epithelial and not neuroepithelial in nature; hence, the term residual ESs (RESs) would be more applicable for diagnostic * Yumi Ito [email protected]