Human papilloma virus (HPV) is not implicated in the etiology of Warthin's tumor of the parotid gland

Pathogenesis of Warthin's Tumor: Neoplastic or Non-Neoplastic?

Warthin's tumor is the second most frequent neoplasm next to pleomorphic adenoma in the salivary gland, mostly in the parotid gland. The epithelial cells constituting a tumor are characterized by the presence of mitochondria that undergo structural and functional changes, resulting in the development of oncocytes. In addition to containing epithelial cells, Warthin's tumors contain abundant lymphocytes with lymph follicles (germinal centers) that are surrounded by epithelial cells. The pathogenesis of Warthin's tumor is not fully understood, and several hypotheses have been proposed. The risk factors for the development of Warthin's tumor, which predominantly occurs in males, include aging, smoking, and radiation exposure. Recently, it has been reported that chronic inflammation and aging cells promote the growth of Warthin's tumor. Several reports regarding the origin of the tumor have suggested that (1) Warthin's tumor is an IgG4-related disease, (2) epithelial cells that compose Warthin's tumor accumulate mitochondria, and (3) Warthin's tumor is a metaplastic lesion in the lymph nodes. It is possible that the pathogenesis of Warthin's tumor includes mitochondrial metabolic abnormalities, accumulation of aged cells, chronic inflammation, and senescence-associated secretory phenotype (SASP). In this short review, we propose that DNA damage, metabolic dysfunction of mitochondria, senescent cells, SASP, human papillomavirus, and IgG4 may be involved in the development of Warthin's tumor.

Surgical treatment strategy in Warthin tumor of the parotid gland

Introduction

Warthin tumors are the second most common benign tumors of the parotid gland. We examined the clinical features of Warthin tumors in our hospital, and analyzed the consistency within the literatures.

Objective

The aim of this study is to analyze the clinical features of Warthin tumors in our 10-year experience of 118 Warthin tumors undergoing surgery at a single institute.

Methods

From December 2006 to December 2016, 110 patients who underwent surgical treatment for Warthin tumors were identified based on their medical records.

Results

A total of 118 parotid gland operations were performed in 110 patients. Almost 90% of Warthin tumors were found in males, and average patient age was 66.1 ± 6.1 years. The prevalence of smoking history was 89.1% (98/110). Eight patients (7.3%) had bilateral Warthin tumors. Seventy-seven lesions (65.3%) were located in the parotid tail portion, followed by 34 lesions in the superficial lobe (28.8%) and 7 lesions in the deep lobe (5.9%).

Conclusion

We determined the appropriate extent of surgery depending on the fine needle aspiration cytology and tumor location by computed tomography scans. Partial facial dysfunction after the operation was detected in 12 cases, and facial nerve function recovered within 3 months. Only one patient experienced a recurrence, and was disease free after the re-operation. We suggest that our treatment algorithm, depending on the location of tumors and the result of fine needle aspiration cytology, can be useful to determine the appropriate extent of surgery for Warthin tumors.

A proportion of primary squamous cell carcinomas of the parotid gland harbour high-risk human papillomavirus

AIMS

In the current study, we aimed to examine primary parotid squamous cell carcinoma (ParSCC) for the presence of high-risk human papillomavirus (HR-HPV) and associated molecular alterations.

METHODS AND RESULTS

Eight cases of ParSCC were retrieved after a detailed clinicopathological review to exclude the possibility of metastasis and/or extension from another primary site. HR-HPV status was determined on the basis of immunohistochemistry (IHC) for p16 expression and chromogenic in-situ hybridization (CISH) for HR-HPV. All cases were genotyped with a multiplexed mass spectrometry assay interrogating 91 hotspot mutations in eight cancer-related genes (EGFR, KRAS, NRAS, BRAF, PIK3CA, AKT1, MEK1 and ERBB2), and studied by fluorescence in-situ hybridization for PTEN copy number alteration. Three of eight cases (37.5%) were positive for the presence of HR-HPV by CISH and p16 IHC. One of three (33%) HR-HPV-positive cases harboured a PTEN hemizygous deletion, and one (33%) HR-HPV-positive case harboured a PIK3CA E545K somatic mutation. No alteration of the PTEN-PI3K pathway was detected in HR-HPV-negative tumours. Over a median follow-up period of 66.2 months, only the patient with the HR-HPV-positive PIK3CA-mutated tumour died of his disease, the remaining seven patients being disease-free.

CONCLUSIONS

Given the established aetiological role of HR-HPV in other head and neck squamous cell carcinomas, it is likely that HR-HPV represents an oncogenic driver in the pathogenesis of more than one-third of ParSCCs. The presence of HR-HPV in ParSCC may be coupled with alterations in the PTEN-PI3K pathway. Further studies on HR-HPV and the molecular characterization of a larger number of ParSCCs are needed to determine the clinical significance of these findings.

Warthin's tumour: Aetiopathogenesis dilemma, ten years of our experience

Despite the volume of studies written after the initial report by Hildebrand (1895) on Warthin's tumour (WT), its aetiopathogenesis continues to be an unresolved and controversial question. Many different genetic and/or environmental aetiological factors seem to act on heterotopic ductal inclusions and may give rise to WT following an unknown tumorigenic event. Recent studies discussed the importance of immunological reactions during the formation of the tumour. A hypersensitive/allergic reaction may play a role in epithelial proliferation and may stimulate the reactivity of the germinal centres in the lymphoid stroma as showed at histological examination. The aim of this study was to inform readers of the current understanding of possible risk factors with a suggested aetiological role in Warthin's tumorigenesis. From 2001 to 2011, a total of 342 patients with benign salivary neoplasm were admitted in the Department of Maxillofacial Surgery of the University of Naples "Federico II". A histological diagnosis of WT was made in 115 of the patients (33.6%); these were retrospectively investigated in our study. Correlation between the onset of WT and positivity for autoimmune diseases and smoking habits was calculated. The incidence rate of autoimmune thyroiditis in our series (9.5%) was significantly greater than that of the general population (0.58%) (p < 0.001). Analysis of our series and review of the literature support the hypothesis that this tumour is the result of an autoimmune reaction. Further studies and larger series are required to confirm this hypothesis and investigate the role of other aetiological factors in WT genesis.