Comments on "The tubarial salivary glands: First description of a potential new organ at risk for head-neck radiotherapy"

A Prospective Evaluation of Tubarial Gland Doses With Acute Dysphagia and Treatment Tolerance in Head and Neck Cancer Patients

Background This study prospectively analyzed the clinical significance of tubarial glands (TGs) doses in head and neck cancer (HNC) patients. Methods Patients diagnosed with HNC in Ankara Bilkent City Hospital, Turkey were analyzed. TGs volumes and doses were noted. The patients were evaluated in terms of acute dysphagia (AD) and radiation therapy (RT)-associated xerostomia. Results The median volume of the TGs was 3.5(2.1-5.9)cc. No increased standardized uptake values (SUV) were observed in the TGs. There was no significant relationship between TGs values and the third or sixth months of xerostomia after RT. There was a significant relationship between grade ≥2 AD and TGs-Dmean (p0.020); TGs-V25(%) (p0.007); TGs-V30(%) (p0.009); TGs-V40% (p0.011); TGs-V50% (p0.010), TGs-V60% (p0.045). In terms of the risk of grade ≥2 AD, the cut-off value of the TGs-Dmean was analyzed for 50 Gy, with 75% sensitivity and 73.3% specificity (p 0.020; AUC 0.746; 95% CI 0.561-0.929). Additionally for grade ≥2 AD, the cut-off value of the TGs-V25(%) was analyzed 78 with 81.3% sensitivity and 80.0% specificity (p 0.011; AUC 0.769; 95% CI 0.591-0.947). Conclusion A significant correlation was found between TGs doses and AD during RT. TGs-V25(%) value showed higher significance. In future studies, the clinical significance of TGs can be studied especially on this value. The relationship between TGs doses and xerostomia should be evaluated with a larger series.

Initial evaluation and external validation of 68Ga-PSMA-11 PET/CT in tubarial gland characterization

INTRODUCTION

Radiotracer 68Ga-PSMA-11 used in PET/CT scans allows for identification and localization of gland tissue. It allows for their consideration in clinical scenarios and to design further and stronger research to answer pertinent questions regarding their function and implications. We aimed to externally validate first reported findings of location, size, and ligand uptake of the tubarial glands using 68Ga-PSMA-11 PET/CT.

MATERIALS AND METHODS

A cross-sectional study was performed with 68Ga-PSMA-11 PET/CT studies of patients with prostate cancer confirmed diagnosis from the database of the Radiology Department from 2018 to 2022. The maximum cephalocaudal length (CCL) in the tubarial glands and the Maximum Standardized Uptake Value (SUVmax) of major glands were recorded.

RESULTS

A total of 202 patients were included (mean age 67.43 ± 8.5). The mean CCL of the tubarial glands was 37.38 ± 9.84 and a SUVmax of 6.56 ± 2.14. The rest of the glands were as follows: parotid 15.12 ± 4.43, submandibular 16.82 ± 5.43 and sublingual 5.84 ± 3.24. No differences were found between laterality. A weak correlation between age and SUVmax of tubarial glands was identified. Tubarial glands had a similar 68Ga-PSMA-11 uptake to that of sublingual glands.

CONCLUSION

This study corroborates the existence of a conglomerate of glands in the nasopharynx roof, near the posterolateral pharyngeal recess. It serves as validation in a different population with similar results in previous research. Without 68GA-PSMA-11 PET/CT the abundance, configuration and potential clinical relevance of these glands would probably not have been identified. Radiotracer uptake was similar amongst the major salivary glands, with a more similar uptake to that shown by the sublingual gland.

Immunohistological profiling confirms salivary gland-like nature of the tubarial glands and suggests closest resemblance to the palatal salivary glands

BACKGROUND AND PURPOSE

High label uptake in 68 Ga-PSMA-11 PET/CT recently identified a bilateral nasopharyngeal structure as a salivary gland (SG)-like additional 'area of interest', to be considered in conditions affecting SGs. These structures were termed 'tubarial glands'. We aimed to further characterize their histological and immunohistochemical position compared to established SGs.

METHODS

Tubarial gland tissue was compared with parotid, submandibular, sublingual, palatal and labial SGs tissue using immunohistological techniques.

RESULTS

Expression of acinar cell-associated aquaporin-5 (AQP5) was detected in tubarial glands, in an apical location associated in control, established SGs with polarized, secretory acinar cells. Keratin14 (KRT14) expression in cells peripheral to AQP5+ clusters also suggested presence of myoepithelial cells. α-amylase, prolactin-induced protein, proline rich protein Haelll subfamily 2, and Muc5B expression suggests mucous acinar cell presence, and presence of muco-serous acinar cells peripheral to putative mucous acinar cells. Expression of adrenergic receptor-β1 by acinar-like cells of the tubarial gland suggests ability to transduce sympathetic neuronal signaling. In terms of ductal architecture, tubarial glands contained large excretory-like ducts (similar to all other SGs), and squamous ducts, comprised of intermingled KRT14+ and KRT7+ cells. These squamous ducts were also observed in palatal, sublingual and labial SGs. No striated or intercalated ducts were observed, similar to palatal SGs.

CONCLUSION

Based on histological and immunohistochemical analyses, the tubarial glands resemble SGs. They most convincingly echo characteristics of the palatal SGs in terms of ductal cells, and both the palatal and labial SGs when considering acinar cells.

Morpho-functional characterization of the submucosal glands at the nasopharyngeal end of the auditory tube in humans

BACKGROUND

The auditory tube (AT), an osteocartilaginous channel, connects the nasopharynx to the middle ear cavity. At the nasopharyngeal opening of the AT, there are dense collections of submucosal glands. In a recent article, Valstar et al. proposed these nasopharyngeal tubal glands conglomerate as salivary glands, which starkly contrasts with their previously known anatomy for being a component of the respiratory tract. This study examines the contesting views regarding the taxonomical categorization of the nasopharyngeal tubal glands.

MATERIALS AND METHODS

The AT glands in context were examined in human cadavers grossly, and microscopically using routine and special (Hematoxylin and Eosin [H&E] and Periodic acid-Schiff [PAS] respectively), as well as immunohistochemical (for alpha-SMA and salivary amylase) staining methods and compared with the major and minor salivary glands and the submucosal glands in the trachea. Further, a biochemical analysis was performed to detect the presence of salivary amylase in the oral and nasopharyngeal secretions of the four living human subjects, representing major salivary glands and tubal glands, respectively.

RESULTS

The submucosal seromucous glands with a surface lining of respiratory epithelium were observed at the nasopharyngeal end of AT. The cells in the tubal glands showed cytoplasmic positivity for alpha-SMA, which indicated the presence of the myoepithelial cells; however, this expression was significantly lower than in the seromucous submucosal glands within the trachea. Salivary alpha-amylase was undetectable in the cadaveric tissue samples. Moreover, the amylase level in the nasopharyngeal swabs was negligible compared to the oral swabs.

CONCLUSION

The anatomical location along the respiratory tract, the presence of respiratory epithelium in the overlying mucosa, their morpho-functional resemblance to the seromucous glands in the trachea, and the absence of salivary amylase strongly indicate that the tubal glands are taxonomically different from the salivary glands. Given the available evidence, their existing recognition as a part of the respiratory tract and an integral component of the AT seems more appropriate.

Histologic Investigation of the Salpingopharyngeus

PURPOSE

The purpose of this study was to characterize the histologic contents of the salpingopharyngeal fold. The primary objective was to observe the presence of salpingopharyngeus (SP) muscle fibers, particularly at the section near the muscle origin at the torus tubarius (TT).

METHOD

Histologic samples of the salpingopharyngeal fold from 10 cadavers (six females and four males) were analyzed. Following a head bisection, a tissue sample measuring 5 mm in length along the course of the salpingopharyngeal fold was collected from one side (i.e., right or left). The tissue sample was taken from the estimated base of the TT to a point 5 mm inferiorly. Slides were prepared using a standard histological approach and basic pathological staining and analyzed via bright-field microscopy.

RESULTS

Skeletal muscle fibers were identified in eight of the 10 tissue blocks of the salpingopharyngeal fold, with dense connective tissue identified in the remaining two tissue blocks. Glandular material was also identified in all 10 tissue blocks.

CONCLUSIONS

Skeletal muscle fibers and/or dense connective tissue can be consistently identified in the section of the salpingopharyngeal fold near the TT. Glandular material is also consistently present in this same region of the salpingopharyngeal fold. These findings are discussed in relation to possible functional roles of the salpingopharyngeal fold contents, including the SP muscle.