Major Salivary Glands Research Articles

Submandibular Sialolithiasis Associated with Sialadenitis –A Case Report

Sialadenitis, an inflammation of major salivary glands is commonly associated with the obstruction of the salivary duct due to sialolith. The submandibular gland is particularly susceptible to sialolithiasis. This case report discusses a 33 year old female patient who reported with a swelling below the tongue/floor of the mouth associated with pain for a week A comprehensive investigation has indicated the presence of multiple sialoliths. The treatment involved surgical removal of the sialoliths, accompanied by antibiotic therapy. Therefore, this case report emphasizes the presence of multiple sialoliths in a female patient.

Stroma-and Tumor-Associated Predictive Features inSalivary Gland Adenoid Cystic Carcinoma of the Headand Neck.

There is lack of knowledge on the utility of prognostic histopathologic characteristics in adenoid cystic carcinoma (ACC) of the head and neck. We evaluated the prognostic value of tumor and stroma-related histopathologic features in ACC. A total of 65 cases of ACC from minor and major salivary glands were included in this study. We evaluated tumor budding, tumor-infiltrating lymphocytes (TILs), and tumor-stroma ratio (TSR) in hematoxylin and eosin (HE) stained sections. Stroma-rich ACCs recurred more frequently (p = 0.029) during follow-up and associated with distant metastasis (p = 0.038). In multivariable analysis, stroma-rich tumors associated with poorer disease-specific survival with a hazard ratio of 3.76 (95% CI 1.10-12.83, p = 0.034). ACCs commonly showed a low infiltration of TILs as 89% of the tumors was characterized by an immune desert pattern. Low infiltration of TILs associated significantly with increased tumor budding (p = 0.039). Adverse features of TSR and tumor budding are widely expressed in ACC, and stroma-rich tumors are associated with poor prognosis. Low number of TILs in ACC tissue indicates a weak immune response by the host and illustrates the nature of ACC as a relentless malignancy.

Radioanatomy of Salivary Glands

Salivary glands are the first organs of digestion secreting their digestive juices into the oral cavity. Parotid, submandibular, and sublingual glands are the major paired salivary glands in the decreasing order of their size. In addition, multiple small minor salivary glands are noted randomly distributed in the upper aerodigestive tract, including paranasal sinuses and parapharyngeal spaces. The imaging is directed to the major salivary glands. Commonly used imaging methods include plain radiography and conventional sialography. Recently, high-resolution ultrasonography (HRUS) is being increasingly used for targeted salivary gland imaging. However, the advent of cross-sectional imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have revolutionized the imaging of salivary glands. This article illustrates the role of imaging in evaluating the variegated disease pattern of the major salivary glands.

Psychological resilience in patients with primary Sjögren's syndrome: effect of involvement of major salivary and lacrimal glands.

The aim of this study was to assess whether the involvement of major salivary and lacrimal glands in primary Sjögren's syndrome (pSS) affected the psychological resilience of patients. This cross-sectional study included 116 patients with pSS. Data were collected through clinical examinations, measurement of salivary flow rates (SFRs), and from Schirmer's test, as well as from patient-reported outcome measures (PROMs), such as the European League Against Rheumatism (EULAR) Sjögren's Syndrome Patient Reported Index (ESSPRI), Brief Resilience Scale (BRS), Work Productivity and Activity Impairment (WPAI), Oral Health Impact Profile-14 (OHIP-14), and the Hospital Anxiety and Depression Scale (HADS). Hyposalivation was defined as an unstimulated SFR of≤0.1mL/min. The BRS score (mean±SD=2.60±0.69) was lower in patients with recurrent parotitis (2.11±0.37) than in those without recurrent parotitis (2.67±0.86), in the whole group. In patients with an unacceptable symptom state (ESSPRI score≥5 points), a lower BRS score was observed in patients with both hyposalivation and ocular dryness (2.59±0.69) than in patients with isolated hyposalivation (2.84±0.84). The BRS score was also negatively associated with the WPAI-Daily Impairment and OHIP-14 scores in patients with hyposalivation as well as with HADS-A (the seven items of HADS relating to the anxiety dimension) and HADS-D (the seven items of HADS relating to the depression dimension) in the whole group. The results suggest that psychological resilience in pSS may be affected by recurrent parotitis, the levels of anxiety and depression, as well as hyposalivation with ocular dryness.

Acinic cell carcinoma of left parotid gland: A case report

Acinic cell carcinoma (ACC) is an uncommon and gradually developing tumour primarily found in the major salivary glands, most frequently originating in the parotid gland and less commonly in the submandibular and sublingual glands. ACC represents 3 to 4% of parotid gland tumours, 2 to 6% of all salivary gland tumours, and 10 to 17% of all malignant tumours in the salivary glands.

Using Machine Learning on MRI Radiomics to Diagnose Parotid Tumours Before Comparing Performance with Radiologists: A Pilot Study.

The parotid glands are the largest of the major salivary glands. They can harbour both benign and malignant tumours. Preoperative work-up relies on MR images and fine needle aspiration biopsy, but these diagnostic tools have low sensitivity and specificity, often leading to surgery for diagnostic purposes. The aim of this paper is (1) to develop a machine learning algorithm based on MR images characteristics to automatically classify parotid gland tumours and (2) compare its results with the diagnoses of junior and senior radiologists in order to evaluate its utility in routine practice. While automatic algorithms applied to parotid tumours classification have been developed in the past, we believe that our study is one of the first to leverage four different MRI sequences and propose a comparison with clinicians. In this study, we leverage data coming from a cohort of 134 patients treated for benign or malignant parotid tumours. Using radiomics extracted from the MR images of the gland, we train a random forest and a logistic regression to predict the corresponding histopathological subtypes. On the test set, the best results are given by the random forest: we obtain a 0.720 accuracy, a 0.860 specificity, and a 0.720 sensitivity over all histopathological subtypes, with an average AUC of 0.838. When considering the discrimination between benign and malignant tumours, the algorithm results in a 0.760 accuracy and a 0.769 AUC, both on test set. Moreover, the clinical experiment shows that our model helps to improve diagnostic abilities of junior radiologists as their sensitivity and accuracy raised by 6 % when using our proposed method. This algorithm may be useful for training of physicians. Radiomics with a machine learning algorithm may help improve discrimination between benign and malignant parotid tumours, decreasing the need for diagnostic surgery. Further studies are warranted to validate our algorithm for routine use.

Morphology of Larger Salivary Glands in Peccaries (Pecari tajacu Linnaeus, 1758).

This work aims to study the major salivary gland morphology of peccaries during their growth. The glands were analyzed using macroscopic description, light microscopy, electron microscopy, histochemistry, and immunohistochemistry. Topographically, the salivary glands resemble other animals, including domestic animals and pigs. During growth, the parotid enlarges and mandibular gland loses weight. Histologically, the parotid has serous production, and sublingual has mucous production, resembles most species, however, mandibular gland produces mucous, unlike other animals, including pigs, which produce seromucous secretion. Histochemically, parotid produces more acidic mucins than pigs and it undergoes maturation during development; mandibular, and especially the sublingual gland, produce more acidic and basic mucopolysaccharides than pigs. The results found with transmission and scanning electron microscopy techniques corroborate the histological and histochemistry findings. The major salivary glands were positive to different lecithins (Com-A, BSA-I-B4, WGA and PNA), which were also more positive than in pigs and sheep. We conclude that collared peccaries have a salivary secretion that facilitates the digestion of carbohydrates, and biometric characteristics and positivity to lecithins that facilitate adaptation to foods with antinutritional factors.

HMGA2-positive salivary gland neoplasms with prominent trabecular/canalicular morphology: a focus on carcinomas arising within this phenotype.

Pleomorphic adenoma (PA) with a prominent trabecular/canalicular morphology has consistent HMGA2 protein expression, and association with HMGA2 fusions. We report our experience with this subtype, with emphasis on the carcinomas that can arise in this context. A retro- and prospective review (2013-2024) of major salivary gland tumours with prominent trabecular/canalicular morphology was performed. Twenty-one parotid tumours met the criteria: 14 benign (66.7%), six carcinomas (28.6%), and one of uncertain behaviour (4.7%). HMGA2 immunohistochemistry (IHC) was performed on all cases. Next-generation sequencing was successfully performed on 18. Seven benign cases had a conventional PA component. In all cases, the tumour cells in these trabecular/canalicular areas demonstrated variable papillary thyroid carcinoma-like nuclear changes, including chromatin clearing, overcrowding, membrane irregularities, and intranuclear pseudoinclusions. Benign tumours were well-demarcated, whereas carcinomas demonstrated either a multinodular pattern of invasion or subtle infiltration. Two carcinomas showed increased cytologic atypia and architectural complexity and one had perineural invasion. By IHC, all were positive for HMGA2. In the trabecular/canalicular areas, there was consistent strong expression of CAM5.2, S-100, and SOX-10 and variable expression of p63 but negative p40. HMGA2 alterations were detected in 16 of 18 cases (89%). Follow-up was available on two carcinomas, with one being locally recurrent. While most HMGA2-positive salivary gland neoplasms with a prominent trabecular/canalicular growth pattern are benign, they, like traditional PAs, may give rise to carcinomas that can locally recur. These carcinomas can be deceptively bland, subtly infiltrative, or have a multinodular pattern of invasion.

A rare pathology that mimics lung cancer: IgG4-related vasculitis.

Immunoglobulin-G4 (IgG4)-related disease is essentially a fibro-inflammatory disease that can affect any organ simultaneously or at different times. The disease usually presents with organ growth that mimics a tumour and can affect the lacrimal glands, major salivary glands, pancreas, bile ducts, retroperitoneal area, lungs, kidneys, aorta, meninges and thyroid gland. The immunopathogenesis behind this new disease has not yet been elucidated. Histopathological distinguishing features of the disease include dense lymphoplasmocytic infiltrates dominated by IgG4 positive plasma cells, storiform fibrosis and obliterative phlebitis. The likelihood of developing with immunoglobulin G4 (IgG4-RD) is a recently identified rare systemic fibroinflammatory disease with an estimated incidence of less than 1 in 100,000 people worldwide. We present our case, which was diagnosed with IGG4-related vasculitis by lung fine needle aspiration biopsy, which is very rare in the literature.

Pancreatic Differentiation of Oral Minor Salivary Gland Stem Cells.

Stem cells from various sources including major salivary glands have been used to establish pancreatic differentiation in an attempt to provide new treatment options for patients with diabetes mellitus. In contrast, the potential of using the more easily accessible intraoral minor salivary glands has not been evaluated so far. Salivary stem cells were isolated from normal labial minor salivary glands that were removed during the excision of a mucocele and were attempted to differentiate into pancreatic cell lines using a culture medium enriched with activin A, retinoic acid and GLP-1.Real time RT-PCR was used to evaluate the expression of the genes of pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx. Complementary, 22 labial minor salivary gland paraffin-embedded specimens were examined using immunohistochemistry for the presence of the relevant gene products of the pancreatic transcription factors Arx, MafA, Ptf1a and Pdx1. The differentiated salivary stem cells(cells of passage 3) expressed the genes of the pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx even on the first day of the experiment while immunohistochemistry also confirmed the presence of the protein products of Arx, MafA, Ptf1a as well as Pdx1[> 50% of the specimens for Arx(5/8) and MafA(7/8), < 50% for Ptf1a(5/11) and Pdx1(5/11)] in ducts, mesenchymal connective tissue and acinar cells. Labial minor salivary glands may share gene and protein characteristics with pancreas suggesting a possible usefulness for pancreatic regeneration or substitution in cases of deficiency.

Proton- compared to X-irradiation leads to more acinar atrophy and greater hyposalivation accompanied by a differential cytokine response.

Proton therapy gives less dose to healthy tissue compared to conventional X-ray therapy, but systematic comparisons of normal tissue responses are lacking. The aim of this study was to investigate late tissue responses in the salivary glands following proton- or X-irradiation of the head and neck in mice. Moreover, we aimed at investigating molecular responses by monitoring the cytokine levels in serum and saliva. Female C57BL/6J mice underwent local fractionated irradiation with protons or X-rays to the maximally tolerated acute level. Saliva and serum were collected before and at different time points after irradiation to assess salivary gland function and cytokine expression. To study late responses in the major salivary glands, histological analyses were performed on tissues collected at day 105 after onset of irradiation. Saliva volume after proton and X-irradiation was significantly lower than for controls and remained reduced at all time points after irradiation. Protons caused reduced saliva production and fewer acinar cells in the submandibular glands compared to X-rays at day 105. X-rays induced a stronger inflammatory cytokine response in saliva compared to protons. This work supports previous preclinical findings and indicate that the relative biological effectiveness of protons in normal tissue might be higher than the commonly used value of 1.1.

Complications after fine-needle aspiration cytology and core-needle biopsy in benign head & neck neoplasms

IntroductionBenign neck masses are one of the most common causes of clinical consultation in head & neck (H&N) clinics. Fine needle aspiration cytology (FNAC) and core needle biopsy (CNB) have become among the main strategies for the diagnostic work-up of palpable and non-palpable neck lumps. Moreover, numerous studies have established the safety, high diagnostic yield, and added value of image-guided H&N biopsies, which play an important role in diagnosis, staging, and treatment planning, and can obviate the need for surgery for many patients. Nonetheless, despite the success of both techniques, there is a lack of recent studies regarding their safety and associated complication rates. Material & methodA retrospective analysis was performed of prospective data on patients undergoing ultrasound-guided FNAC or CNB for benign H&N disease (e.g., salivary gland benign tumors, branchial cleft cyst, thyroglossal duct, cyst, lipoma, or neurinoma) between June 2016 and June 2021 in a tertiary university hospital. ResultsOverall, 192 patients were included (105 [54.7%] men and 87 [45.3%] women). The Kolmogorov-Smirnov test indicated that our data were normally distributed (p = 0.452). The mean age of enrolled patients was 54 ± 10 (range: 18–87). The anatomical site most commonly affected was a major salivary gland (74%). Regarding incidence and type of complications, nine (4.7%) patients experienced complications, infection being the most common problem. The risk of complications was highest in patients with branchial cleft cysts who had undergone FNAC (p = 0.028). Overall, the risk of complications was not associated with the type of technique (p = 0.603; OR: 0.942; 95% confidence interval = 0.245–3.624). ConclusionAccording to our results, FNAC and CNB are generally safe and reliable procedures in the diagnostic work-up of H&N lumps. Nevertheless, physicians should be aware of certain risks associated with these procedures.

Clinical Profile and Histopathological Pattern of Major Salivary Gland Tumors in a Nigerian Tertiary Hospital

Abstract Background: Varieties of tumors can arise from major salivary glands primarily or secondarily. Over 30 histological subtypes have been documented by the World Health Organization, serving as a guide in diagnosis and management. Objectives: To evaluate the clinical and histological pattern of presentation of major salivary gland tumors. Materials and Methods: This is a clinical retrospective study, done at the University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu, Nigeria, assessing records of patients with major salivary gland tumors seen between January 2018 and December 2022. Data obtained were analyzed using Statistical Package for Social Sciences version 26. The results were presented in tables and charts and comparisons were made using the Chi-squared test. Results: Out of the 57 patients with major salivary gland tumors studied, 30 (52.6%) were benign tumors, and 27 (47.4%) were malignant tumors. About 63.2% of patients were predominantly females, whereas 36.8% were males with a male-to-female ratio of 1:1.7. The most common presenting symptom was swelling. The average duration of symptoms before presentation was 24 and 12 months for benign and malignant tumors, respectively. The parotid gland (61.4% total) was the most common site of tumor presentation for both benign and malignant tumors followed by the submandibular and sublingual the least. The most common histological variant was pleomorphic adenoma (40.4%) for benign and mucoepidermoid carcinoma (28.1%) for malignant. Surgery was the first line of treatment given. Conclusion: The observed pattern of clinical and histological presentation of major salivary gland tumors will guide clinicians on the approach for the management.

Pleomorphic adenoma of hard palate: Review of updated literature and "case report".

Pleomorphic adenoma (PA) is a rare benign tumor mainly affecting the major salivary glands, known for its diverse histological appearances that can mimic malignancies. When it occurs in the hard palate it present diagnostic and management challenges compared to other sites due to the anatomical location and potential proximity to critical structures. This case reports a rare presentation PA starting as an ulcer, alongside a review of rare cases of PA reported in last 5 years. We aim to highlight clinical challenges and emphasize the need for awareness in diagnosis of this diverse entity amongst the clinicians before reaching a definitive conclusion. A 41-year-old female reported an asymptomatic large swelling on the right side of the posterior palatal region. Clinical diagnosis revealed a firm, rubbery, and non-tender swelling of approximately 4 cm × 4 cm diameter. A triangular incisional biopsy was performed to confirm the diagnosis. The histopathological evaluation confirmed the presence of a PA with a well-encapsulated and compressed salivary gland. A wide surgical dissection was made to remove the entire encapsulated tumor mass, including the mucoperiosteum and eroded bone of the palate. The borderline of the tumor was carefully identified in the surrounding healthy tissue. The hemostasis was obtained using a simple interrupted suture. The diagnosis of PA is difficult as it usually involves extensive squamous and mucous metaplasia, confusing it with malignant disorders. Histopathological and clinical examinations are important for differentiating this lesion from other tumors. Complete surgical excision is reported as the first line of treatment.

DNA Methylation Profiling of Salivary Gland Tumors Supports and Expands Conventional Classification

Tumors of the major and minor salivary glands histologically encompass a diverse and partly overlapping spectrum of frequent diagnostically challenging neoplasms. Despite recent advances in molecular testing and the identification of tumor-specific mutations or gene fusions, there is an unmet need to identify additional diagnostic biomarkers for entities lacking specific alterations. In this study, we collected a comprehensive cohort of 363 cases encompassing 20 different salivary gland tumor entities and explored the potential of DNA methylation to classify these tumors. We were able to show that most entities show specific epigenetic signatures and present a machine learning algorithm that achieved a mean balanced accuracy of 0.991. Of note, we showed that cribriform adenocarcinoma is epigenetically distinct from classical polymorphous adenocarcinoma, which could support risk stratification of these tumors. Myoepithelioma and pleomorphic adenoma form a uniform epigenetic class, supporting the theory of a single entity with a broad but continuous morphologic spectrum. Furthermore, we identified a histomorphologically heterogeneous but epigenetically distinct class that could represent a novel tumor entity. In conclusion, our study provides a comprehensive resource of the DNA methylation landscape of salivary gland tumors. Our data provide novel insight into disputed entities and show the potential of DNA methylation to identify new tumor classes. Furthermore, in future, our machine learning classifier could support the histopathologic diagnosis of salivary gland tumors.

Predictive value of neutrophil to lymphocyte ratio, platelet to lymphocyte ratio, and systemic inflammatory index for detection of recurrence of pleomorphic adenoma of the major salivary glands: a multicenter study

BackgroundThe aim of this study was to investigate the correlation between inflammatory biomarkers such as the systemic immune-inflammation index (SII), the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) and the recurrence of pleomorphic adenomas (PAs). MethodsRetrospective multicenter study. 608 patients diagnosed with PA and treated by tumor enucleation were included in the analyses. The patients. were extracted from a twenty-year database of two referral centers (January 2000 to January 2020). Data about age, sex, voluntary habits, tumor characteristics, tumor treatment and values of NLR, PLR and SII were collected. A receiver operating characteristic (ROC) curve was used to calculate the optimal cut-off values for SII, PLR and NLR. A linear regression model (LRM) and a non-linear logistic regression model (NLRM) were implemented for NLR, PLR and SII. ResultsAll three inflammatory parameters were statistically significant correlated to the recurrence of the tumor. The best performance was achieved by NLR (cut-off 2.960) with AUC = 0.91, accuracy of 96.1%, sensitivity of 78.4% and specificity of 97.2%, PPV = 64.4% and NPV = 98.6%. LRM and NLRM including all hematological parameters did not improve performance in terms of recurrence detection. ConclusionThe use of three inflammatory biomarkers could be a useful tool to predict recurrence of tumor in case of PA ≤ 3 cm. NLR in particular could be sensitive with a cut-off of 2.960. The use of NLR, PLR and SII could be a good reference point for surgical decision making and follow-up in clinical practice.

Contribution of kelp dashi liquid to sustainable maintenance of taste sensation and promotion of healthy eating in older adults throughout the umami-taste salivary reflex.

Taste decline, including taste loss in older adults, leads to malnutrition and frailty. In a super-aging society, improving taste decline and maintaining taste sensation are crucial for the wellbeing of older adults. Hyposalivation frequently affects older individuals and is the leading cause of taste decline in older adults. Treating taste decline, including taste loss, in older adults presents challenges due to the limited sustainable methods for increasing saliva production, except for drug therapy, which may lead to adverse effects. Umami-taste stimulation results in a prolonged increase in both the whole salivary flow rate (WF), more than 90% of which is secreted from the major salivary glands, and the minor salivary gland flow rate (MF) in healthy volunteers through the umami-taste salivary reflex. We hypothesized that umami-rich kelp dashi liquid (KDL), commonly used in Japanese cuisine, may alleviate taste decline and sustain normal taste sensation in older adults with hyposalivation. This study investigated whether KDL stimulation could improve taste decline. A non-randomized controlled trial was conducted at the dental department of a university hospital, involving those who presented with dry mouth between May 2017 and December 2021. Before and after repeated KDL stimulation, characteristics like changes in WF and MF, the recognition thresholds (RTs) for five basic tastes, and subjective eating and swallowing difficulties were assessed. Statistical comparisons were performed between the values measured before and after KDL stimulation. A total of 35 older patients were included. Patients with reduced MF and with or without reduced WF exhibited umami-taste loss. Repeated stimulation with KDL increased MF and WF and improved taste loss, including umami, decreased RTs, and normalized each taste. Furthermore, subjective taste impairment, subjective eating and swallowing difficulties, and burning sensations in the oral mucosa were alleviated. These findings indicate that KDL stimulation improved umami-taste loss and normalized each taste sensation, further alleviating eating difficulties via the umami-taste salivary reflex. Importantly, umami-taste loss was also observed in patients with normal WF but decreased MF, who are typically not diagnosed with hyposalivation. Therefore, KDL has the potential to sustain taste sensations and promote healthy eating habits in older individuals.

A comprehensive analysis of the tubarial glands.

The tubarial glands (TGs) are a collection of salivary glands (SGs) located within the nasopharynx, proximal to the eustachian tube. Currently, there is no quantitative characterization of the TGs. We investigated the histological architecture of the TGs and compared it with the major and minor SGs for categorization. Tubarial, parotid, submandibular, sublingual, buccal, labial, and lingual glands were excised from human donors (8 male and 3 female). Hematoxylin and eosin-stained tissue sections were analyzed to measure the area of the largest lobule, number of ducts, number of mucinous acini, and mean mucinous acini area. Based on our observation, the TGs' histology resembles the minor SGs, while having some unique characteristics that distinguish them from both major and minor SGs. The area of the largest lobule in the TGs and minor SGs was smaller than the major SGs. TGs have a lower number of ducts than the major and minor SGs. TGs contain densely packed clusters of predominantly mucinous acini surrounded by loose connective tissue resembling minor SGs. This density may explain their previously observed high prostate-specific membrane antigen uptake. In our cohort of donors, sex-based differences were observed in the mean mucinous acini area between male and female TGs, submandibular and sublingual glands. Taken together, our findings suggest the histological characteristics of all SGs are better organized on a spectrum rather than discrete groups (major vs. minor) and provide information to open new avenues for research into the TGs' role in head and neck pathologies and sexual dimorphism of the SGs.

Accuracy of two-dimensional transverse wave elastography of salivary glands in diagnosis of Sjögren’s disease: a systematic review and meta-analysis

ObjectivesTwo-dimensional shear wave elastography (2D-SWE) is a non-invasive technique for the evaluation of Sjögren’s disease (SjD). This study investigated the diagnostic accuracy of 2D-SWE in assessing major salivary gland involvement...

Lysophospholipase D activity on oral mucosa cells in whole mixed human saliva involves in production of bioactive lysophosphatidic acid from lysophosphatidylcholine

We reported that lysophosphatidic acid (LPA) is present at 0.8 μM in mixed human saliva (MS). In this study, we examined the distribution, origin, and enzymatic generation pathways of LPA in MS. LPA was distributed in the medium and cell pellet fraction; a true level of soluble LPA in MS was about 150 nM. The soluble LPA was assumed to be generated by ecto-type lysophospholipase D on exfoliated cells in MS from LPC that originated mainly from the major salivary gland saliva. Our results with the albumin-back extraction procedures suggest that a significant pool of LPA is kept in the outer layer of the plasma membranes of detached oral mucosal cells. Such pool of LPA may contribute to wound healing in upper digestive organs including oral cavity. We obtained evidence that the choline-producing activity in MS was mainly due to Ca2+-activated lysophospholipase D activity of glycerophosphodiesterase 7.