Transitional features of benign and malignant oncocytic tumors: report of two cases

Parotid gland oncocytosis: Multifocal adenomatous oncocytic hyperplasia variant - A case report in Singapore

Oncocytosis is a rare, benign, non-neoplastic lesion that can be further classified into diffuse oncocytosis or multifocal adenomatous oncocytic hyperplasia. This tumour has been estimated to account for 0.1% of all parotid gland tumours.¹ Here, we report a rare case of a patient who presented to the Oral and Maxillofacial Surgery Department with a 3-cm swelling of his left parotid gland. Histopathological results from a superficial parotidectomy revealed the lesion to be a multifocal adenomatous oncocytic hyperplasia of the parotid gland. A description of this rare disease and its management are included in this article.

Oncocytic Lesions of Salivary Glands with Morphological and Immunohistochemical Findings

Objectives:

Salivary gland neoplasms are less than 5% of all head and neck neoplasms (1). Although there are morphological similarities between different neoplasms, there may be catchy morphological differences in a single tumour. According to the World Health Organization (WHO), 4^th Head and Neck Tumours Classification oncocytic salivary gland lesions are classified as nodular oncocytic hyperplasia, oncocytoma and oncocytic carcinoma. Oncocytic cells may be a component of other salivary gland neoplasms and metastatic malignities.

Methods:

In this study, salivary gland oncocytic lesions diagnosed in 2016-2017 were evaluated with Haematoxylin and Eosin (H&E) sections and PAS, diastase resistance PAS, p63, DOG1, cytokeratin7 (CK7), androgen receptor (AR) and PAX8 stains.

Results:

Nineteen cases were benign, two cases were malignant. Eighteen of the benign lesions were Warthin tumour (WT), one case was oncocytoma with nodular oncocytic hyperplasia. Acinic cell carcinoma (AciCCA) with oncocytic cells predominant was one of the malignant cases. The other case was high-grade salivary duct carcinoma (SDCA).

Conclusion:

The rarity and heterogeneity of this group of lesions may cause difficulties in diagnosis. We present histochemical and immunohistochemical findings of these lesions in light of the literature.

Imaging of the Eustachian tube and its function: a systematic review

Introduction

The Eustachian tube is a complex and inaccessible structure, which maintains middle ear ventilation to facilitate transmission of sound from the tympanic membrane to the cochlea. A renewed interest in treatments for eustachian tube dysfunction has led to a demand for methods of imaging the Eustachian tube, and assessing tube opening non-invasively. This review aims to summarise the use of imaging in the anatomical assessment of the Eustachian tube, and to explore how radiological techniques can be used to assess tube function.

Methods

A systematic review of the literature was performed with narrative data analysis.

Results

With high-resolution images, the soft and bony anatomy of the Eustachian tube can be assessed in detail. CT and MRI are best suited to identifying features associated with obstructive or patulous Eustachian tube dysfunction, though true assessments of function have only been achieved with contrast enhanced radiographs and scintigraphy. A single modality has yet to provide a complete assessment. No test has entered routine clinical use, but further development and research is underway.

Conclusion

Significant information can be gained from imaging the Eustachian tube, and as faster acquisition techniques are developed, it is possible that dynamic imaging of tubal opening could play an important role in the assessment of patients with ET dysfunction.

CT features of parotid gland oncocytomas: a study of 10 cases and literature review

Oncocytomas of the salivary glands are rare benign epithelial tumors which occur most commonly in the parotid gland. The aim of our study was to characterize the clinical-radiologic-pathologic spectrum of parotid oncocytomas in a series of 10 cases seen in our institution between January 2003 and November 2008. The CT features of parotid oncocytomas in the largest imaging series of this rare but important benign lesion include a well-defined enhancing tumor with a "deformable" appearance when large, and a non-enhancing curvilinear cleft or cystic component. These CT findings are potentially helpful in distinguishing these benign lesions from other parotid tumors in clinical scenarios that preclude surgical resection or when biopsy results are non-diagnostic. Further studies are advocated to validate the specificity and positive predictive value of these imaging features.

Nonparotid parapharyngeal oncocytoma: a case report and literature review

Oncocytoma is a rare, benign salivary neoplasm composed of mitochondria-rich cells called oncocytes. Although oncocytoma usually occurs in the parotid glands, it has much less commonly been reported to occur in minor salivary gland tissues. Although there have been a few reported cases of oncocytomas being found in the parapharyngeal space, most if not all cases seem to be extensions of deep lobe parotid tumors. We present a case of a 73-year-old man with a previous history of prostate cancer that had the incidental finding of an (18)F-fluorodeoxyglucose (FDG) image of a highly avid parapharyngeal space lesion noted on a follow-up positron emission tomography-computed tomography (PET/CT) scan. Excision of the mass, through a transcervical approach, demonstrated it to be an isolated oncocytoma of the parapharyngeal space, noncontiguous with the parotid gland. Based on our literature search, this may be the first such reported case. A brief review of the available literature examining the known body of knowledge regarding these neoplasms is presented.

Update on eustachian tube dysfunction and the patulous eustachian tube

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent knowledge on eustachian tube dysfunction and the patulous eustachian tube.

RECENT FINDINGS

A clinically useful test for eustachian tube function is still lacking. Narrowing of the isthmus alone was demonstrated to be an insufficient cause of otitis media. Inflammatory mediators identified within the eustachian tube and middle ear cells were causally linked with otitis media with effusion. Increasing evidence was found that allergic disease and reflux may be two of the most important contributors of tubal inflammation causing otitis media with effusion. The adenoid size and proximity to the torus tubaris may also be important in considering which patients with persistent otitis media with effusion may benefit from adenoidectomy. Computed tomography scan has documented loss of soft tissue within the cartilaginous eustachian tube in patients with patulous eustachian tubes. An endoscopic approach to seal the tubal lumen has been found to be effective in relieving patulous symptoms.

SUMMARY

These studies suggest that allergic rhinitis and gastroesophageal reflux should be investigated in patients with eustachian tube dysfunction. Adenoidectomy should also be considered in patients who have adenoids that obstruct the torus tubaris. Patients with a patulous eustachian tube may benefit from an endoscopic closure. Further research is needed to identify a clinically useful test for eustachian tube dysfunction.

Relationship of petrous temporal bone pneumatization to the eustachian tube lumen

OBJECTIVES/HYPOTHESIS

Objectives were to determine the incidence of petrous apex pneumatization and to define the relationship between a pneumatized petrous temporal bone and the eustachian tube lumen.

STUDY DESIGN

Retrospective study with institutional review board approval including only adult patients.

METHODS

One hundred head computed tomography (ct) scans and 204 petrous temporal bone CT scans performed at a tertiary teaching hospital were reviewed. The two senior authors (s.h.s., p.c.s.) independently reviewed the petrous temporal bone CT scans for grade of pneumatization. Pneumatized CT scans were then reviewed for the presence of a direct communication with the eustachian tube lumen. Significance was determined using the chi test and Pearson correlation of ranks.

RESULTS

The incidence of peritubal cells opening into the eustachian tube anterior to the tympanic orifice was 92%.

CONCLUSION

The direct communication of peritubal cells with the bony eustachian tube may play a role in the development of persistent cerebrospinal fluid rhinorrhea after cerebellopontine angle surgery.

Eustachian tube function after translabyrinthine vestibular schwannoma surgery

The objective of this study was to evaluate the short-term and long-term effect of the obliteration of the middle ear and the Eustachian tube on its function and on middle ear anatomy. Forty-two patients who underwent a translabyrinthine removal of a vestibular schwannoma were randomly selected from the 329 patients operated on in the last 5 years. According to the length of follow-up they were divided in two groups. The Eustachian tube was found to open in 40% of cases 8 months (group mean) after the operation and at 4 years in 70% of cases (group mean) after the operation. The mechanisms leading to the opening of the tube are discussed. In addition the absence of long-term middle ear disorders in those with a permanently closed Eustachian tube showed that the presence of atrophied connective tissue and scar tissue in the middle ear prevented the retraction of the tympanic membrane. Obliteration of the Eustachian tube and middle ear is an easy and rapid procedure, which is temporary in most cases and does not increase the risk of long-term middle ear disease.

Oncocytic neoplasms of the parotid gland: a 16-year institutional review

BACKGROUND

Oncocytic neoplasms of the parotid gland are a rare collection of salivary gland tumors that include oncocytosis, oncocytoma, and oncocytic carcinoma. Mounting evidence has linked the presence of oncocytes to acquired mitochondrial dysfunction.

OBJECTIVES

The study goals were to further delineate this poorly understood group of salivary gland tumors and to search for genetic alterations indicative of mitochondrial dysfunction.

METHODS

Cases were identified by search of the surgical pathology archival files from 1984 through 2000. Corresponding medical records were reviewed. Tumor mitochondrial DNA (mtDNA) was evaluated for mtDNA mutations within the control region (C-tract).

RESULTS

Twenty-one parotid oncocytic neoplasms were identified. Oncocytoma was the most frequent morphology (62%), followed by oncocytosis (28.5%) and oncocytic carcinoma (9.5%). One specimen displayed synchronous oncocytic morphologies (oncocytoma, oncocytosis, and oncocytic metaplasia). One oncocytoma specimen displayed the mtDNA C-tract alteration.

CONCLUSIONS

Oncocytic neoplasia of the parotid gland is a rare form of salivary gland disease with obscure etiology. The presence of multiple oncocytic morphologies in a single specimen is suggestive of transition between forms. Although oncocytic tumorigenesis secondary to acquired mitochondrial dysfunction is a plausible mechanism, few of these tumors actually harbor mtDNA alterations within the control region.