Oncocytoma of the parotid gland: a case report and review of the literature

Cystic lesions in the salivary gland. Pitfalls to be avoided on cytology

Cystic lesions of the salivary glands are very uncommon entities. However, on occasion, some neoplasms of the salivary glands show a cystic component, which may be predominant or only partially cystic. Basal cell adenoma, canalicular adenoma, oncocytoma, sebaceous adenoma, intraductal papilloma, epithelial-myoepithelial carcinoma, intraductal carcinoma, and secretory carcinoma are such cystic entities. Cystic degeneration and necrosis, which can develop within solid tumours, represent another possibility. The ability to recognise this type of lesion is a challenge in diagnostic cytology because hypocellular fluid is frequently recovered. Furthermore, evaluating all of the differential diagnoses for cystic lesions of the salivary glands is helpful in obtaining the correct diagnosis. Herein, we evaluate the various types of cystic lesions within the salivary glands.

Incidentally Detected 131-Iodine Avid Parotid Oncocytoma Coexistent with Papillary Carcinoma Thyroid

131-I radioactive iodine (RAI) scan is an important modality in the management of differentiated thyroid cancer to detect recurrent or residual disease. Thus it is important to have knowledge about the possibility of false positive findings in these scans to avoid wrongful diagnosis and unnecessary treatment. We here by present a patient who underwent total thyroidectomy with lymph node dissection and followed by radioactive iodine therapy for papillary thyroid cancer. He had 131-I iodine avid nodular lesion in the left parotid gland which was later proven to be oncocytoma on histopathology. False positive findings on radioactive iodine scans are a possibility which should be known to surgeons as well as nuclear medicine physicians for accurate diagnosis and appropriate management.

Oncocytoid Variant of High-Grade Salivary Duct Carcinoma: A Potential Diagnostic Pitfall. A Report on Two Patients

Salivary duct carcinoma (SDC) is an uncommon and aggressive salivary malignancy. The oncocytoid variant of salivary duct carcinoma (OSDC) has only been reported in the English literature once before. Here we detail two new patients. A 71-year-old female presented with a painless enlarging left parotid mass. Imaging and fine-needle aspiration were nondiagnostic. The second patient, a 79-year-old male, presented with painless swelling in the right cheek. Imaging was nondiagnostic. Both patients underwent surgical resection. Histopathology revealed bland yet infiltrative OSDC in both cases. These tumors were AR+ (androgen receptor) by immunohistochemistry. Potential difficulty exists in distinguishing the oncocytoid variant of SDC, a rare and relatively bland tumor, from oncocytoma, a more commonly encountered entity. AR expression can aid in the correct diagnosis.

Advanced magnetic resonance imaging findings in salivary gland tumors

Salivary gland tumors (SGTs) make up a small portion (approximately 5%) of all head and neck tumors. Most of them are located in the parotid glands, while they are less frequently located in the submandibular glands, minor salivary glands or sublingual gland. The incidence of malignant or benign tumors (BTs) in the salivary glands varies according to the salivary gland from which they originate. While most of those detected in the parotid gland tend to be benign, the incidence of malignancy increases in other glands. The use of magnetic resonance imaging (MRI) in the diagnosis of SGTs is increasing every day. While conventional sequences provide sufficient data on the presence, localization, extent and number of the tumor, they are insufficient for tumor specification. With the widespread use of advanced techniques such as diffusion-weighted imaging, semi-quantitative and quantitative perfusion MRI, studies and data have been published on the differentiation of malignant or BTs and the specificity of their subtypes. With diffusion MRI, differentiation can be made by utilizing the cellularity and microstructural properties of tumors. For example, SGTs such as high cellular Warthin’s tumor (WT) or lymphoma on diffusion MRI have been reported to have significantly lower apparent diffusion values than other tumors. Contrast agent uptake and wash-out levels of tumors can be detected with semi-quantitative perfusion MRI. For example, it is reported that almost all of the pleomorphic adenomas show an increasing enhancement time intensity curve and do not wash-out. On quantitative perfusion MRI studies using perfusion parameters such as Ktrans, Kep, and Ve, it is reported that WTs can show higher Kep and lower Ve values than other tumors. In this study, the contribution of advanced MRI to the diagnosis and differential diagnosis of SGTs will be reviewed.

Sine Qua Non: Oncocytoma

Oncocytomas of the salivary gland are uncommon neoplasms that are characterized by polygonal cells with abundant granular eosinophilic cytoplasm and relatively uniform nuclei. They are benign in nature and have a low recurrence rate with complete surgical excision. Though uncommon, oncocytic and clear cell variants of malignant tumors may histologically mimic oncocytomas and identification of their distinguishing features is essential. A classic example of an oncocytoma is discussed.

Atypia of undetermined significance in the Milan System for Reporting Salivary Gland Cytopathology: Cystic versus non-cystic masses

The term "Atypia" has been employed to describe a wide spectrum of cytomorphologic features associated with reactive/inflammatory processes as well as those suspicious for neoplasms in cytology. Similar to other cytopathology reporting systems, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has reserved the atypical category for cytology specimens lacking quantitative and/or qualitative cytomorphologic features to be diagnosed with confidence as either non-neoplastic or neoplastic. In MSRSGC, the atypical category is associated with a risk of malignancy and recommendation for clinical management. In this review, we discuss the value of atypical diagnostic category of MSRSGC in both cystic and non-cystic salivary gland lesions by evaluating our institutional case cohort.

Parotid Oncocytoma on 99mTc-Sestamibi Scintigraphy and SPECT/CT

ABSTRACT

Oncocytomas in the parotid gland are a rare benign neoplasm composed of mitochondrial-rich oncocytes. Here we present the case of an 85-year-old man with a history of biopsy-proven right parotid gland oncocytoma who underwent 99mTc-sestamibi scintigraphy and SPECT/CT in the context of primary hyperparathyroidism. Focal intense uptake of radiotracer is detected within the right parotid gland on sestamibi scintigraphy. SPECT/CT confirms the localization of sestamibi uptake to the hyperattenuating parotid gland oncocytoma.

Magnetic resonance imaging of salivary gland tumours: Key findings for imaging characterisation

Salivary gland tumours are rare, representing only 3% of all head and neck neoplasms, with the parotid gland being the most common site (80 %). The risk of malignancy is inversely proportional to the size of the gland: lesions arising in the sublingual or minor salivary glands are more likely to be malignant, whereas parotid gland neoplasms are mostly benign. Fine needle aspiration cytology and core needle biopsy are considered the most accurate modalities for the diagnosis of a salivary gland neoplasm; however, they are not always conclusive due to procedural sampling errors and for the presence of a cytological / histological overlap between benign and malignant tumours. Moreover, they cannot be easily performed for parotid deep portion localisation. The role of magnetic resonance imaging (MRI) is growing and advanced techniques (diffusion-weighted and dynamic contrast-enhanced perfusion-weighted imaging) can provide useful additional information for the assessment of salivary gland neoplasms. The aim of this review is to present the main MRI and clinical features of salivary gland tumours to improve their comprehensive evaluation and characterisation.

Imaging features of parotid gland oncocytoma: a case series study

Background

Reports regarding the imaging findings of parotid gland oncocytoma are limited and prospective definitive diagnosis is difficult. This case series is aimed at furthering the knowledge of imaging for parotid gland oncocytoma.

Methods

Seven patients with pathologically confirmed parotid gland oncocytoma were identified between January, 2016 and August, 2020. They were subjected to computed tomography, magnetic resonance imaging or ultrasound. Imaging features of lesions were retrospectively analyzed and documented by a senior radiologist.

Results

Among the 7 recruited parotid gland oncocytoma patients, 4 were males and 3 were females. They were aged between 47 and 87 years with a median age of 63 years. The range of maximum diameter of the mass was about 1.6-4.5 cm, with the median size being 3.5 cm. All cases were unilateral single masses. Three patients had their parotid gland oncocytoma located in the deep lobe of the parotid gland and 4 patients had their parotid gland oncocytoma located in the superficial lobe. Most lesions exhibited a clear boundary and irregular shapes or lobulated, and contain cystic components. Local pain was the most common clinical manifestation. Most of the lesions exhibited a hypoechoic mass on ultrasound, soft tissue density on computed tomography, iso to hypointense signal on T1 weighted imaging, slightly hypersignal on T2 weighted imaging, while contrast-enhanced computed tomography, magnetic resonance imaging, and ultrasound showed avid enhancement.

Conclusions

Parotid gland oncocytomas usually exhibit a clear boundary to surrounding parotid tissue, lobulated or irregular shape and avid enhancement, sometimes accompanied with cystic components. Diagnosis of parotid gland oncocytoma should be considered when these features are encountered in clinical practice.

Diagnostic imaging of parotid gland oncocytoma: a pictorial review with emphasis on ultrasound assessment

Parotid gland oncocytoma (PGO) is a rare benign epithelial tumor that usually occurs in the elderly population. The most common clinical presentation is a painless, slow-growing, non-tender, lobulated, and mobile mass. Histologically, it is composed of monotonous sheets of epithelial cells (oncocytes) with a central scar. The cross-sectional appearance is not specific, and it overlaps with other parotid lesions. On ultrasound (US), oncocytoma appears as an ovoid, well-defined, homogeneous, and hypoechoic lesion. Cystic and hemorrhagic areas as well as intralesional fat may be observed. Doppler analysis shows intratumoral vessels, sometimes with a spoke-wheel pattern. The peak systolic flow is high (up to 100 cm/sec). Furthermore, oncocytoma is avid of FDG on a PET scan, as well as a malignant tumor. Thus, a combined clinical, imaging, and pathologic assessment is essential to establish the most accurate diagnosis and plan the best treatment. US, combined with Doppler techniques, can play an important role in suggesting the diagnosis and confirming it through percutaneous sampling. The purpose of this review is to show the imaging findings in PGO, with special emphasis on the US appearance.

Parotid oncocytoma: CT and pathologic correlation of a rare benign parotid tumor

Oncocytoma, also known as oxyphilic adenoma or mitochondrioma of the parotid gland is a rare benign tumor constituting less than 1.5% of all parotid lesions. As there are no characteristic imaging findings, this lesion often poses a diagnostic and clinical challenge. We present a rare case of a parotid oncocytoma posing a diagnostic challenge in a 55-year-old woman presenting with a facial mass. We hope to bring awareness of this benign entity affecting the parotid gland.

Incidental Findings in TMJ Imaging

For years, the conventional imaging modalities are generally used in dental practice routine. They provide precious information about dentomaxillofacial region; they also have some limitations such as superimpositions, magnifications, distortions, and low-image quality. Because of these limitations, some pathologies, calcifications, and anatomical variations may be missed. Any findings on a radiographic image which are not related to the research areas of interest could be a description of “incidental findings.” Calcifications are one of these incidental findings. They are asymptomatic and also common in TMJ images. Although most of the calcifications require no treatment, correct identification will reduce further diagnostic assessments. Incidental findings on TMJ images were rare, while examining images for temporomandibular disorders and associated issues, it is important not only to examine the TMJ structures but also to look at the nearby anatomical features to check for evidence of incidental findings pathologies that may have mimicked signs and symptoms of TMJ disorders.

Oncocytoma of the Parotid Gland with Facial Nerve Paralysis

Parotid gland tumor with facial nerve paralysis is strongly suggestive of a malignant tumor. However, several case reports have documented benign tumors of the parotid gland with facial nerve paralysis. Here, we report a case of oncocytoma of the parotid gland with facial nerve paralysis. A 61-year-old male presented with pain in his right parotid gland. Physical examination demonstrated the presence of a right parotid gland tumor and ipsilateral facial nerve paralysis of House–Brackmann (HB) grade III. Due to the facial nerve paralysis, a malignant tumor of the parotid gland was suspected and right parotidectomy was performed. Oncocytoma was confirmed histopathologically. The facial nerve paralysis was resolved 2 months after surgery. During the follow-up period (one and a half years), no recurrence was observed. As the tumor showed a distinctive dumbbell shape and increased somewhat due to inflammation (i.e., infection), the facial nerve was pinched by the enlarged tumor. Ischemia and strangulation of the nerve were considered to be the cause of the facial nerve paralysis associated with the benign tumor in this case.

Parotid Oncocytoma as a Manifestation of Birt-Hogg-Dubé Syndrome

Birt-Hogg-Dubé syndrome (BHD) is a rare autosomal dominant disease characterized by skin fibrofolliculomas, pulmonary cysts, spontaneous pneumothoraces, and renal cancers. Oncocytomas are benign epithelial tumors that are also rare. Recently, there have been a few case reports of BHD with a parotid oncocytoma that appears to have a BHD phenotype. Here we document the eighth known case and describe the magnetic resonance imaging features of the parotid oncocytoma, which mimicked Warthin's tumor. Radiologists should be aware of the association between these rare disorders.

Vanishing Parotid Tumors on MR Imaging

Background

Of all parotid gland tumors, only oncocytoma has been reported to appear isointense to the parotid gland, namely vanishing, on fat-saturated T2 and T1 postcontrast gadolinium-enhanced magnetic resonance imaging (MRI). The purpose of this study was to evaluate vanishing of parotid tumors on conventional MRI with and/or without postcontrast gadolinium-enhancement and on diffusion weighted imaging (DWI).

Methods

In 8 of 51 patients, ten parotid gland tumors had homogeneously enhanced lesions and were retrospectively analysed. Comparisons of signal intensity between those parotid tumors and parotid glands and evaluations of vanishing were performed on T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), fat-suppressed T2WI (FS-T2WI), postcontrast gadolinium-enhanced T1WI (CE-T1WI) and fat-suppressed CE-T1WI (FS-CE-T1WI), DWI as well as apparent diffusion coefficient (ADC).

Results

Ten parotid gland tumors consisted of five Warthin tumors, two pleomorphic adenomas, two parotid carcinomas (small cell carcinoma and adenoid cystic carcinoma) and one oncocytoma. All tumors showed hypointensity on T1WI and hyperintensity on DWI. Nine of ten tumors showed vanishing on the other MR sequences. All Warthin tumors showed vanishing on FS-T2WI, FS-CE-T1WI and the ADC map. One oncocytoma showed vanishing on FS-T2WI and the ADC map and hyperintensity on FS-CE-T1WI. All pleomorphic adenomas showed vanishing on T2WI and CE-T1WI. One adenoid cystic carcinoma showed vanishing only on CE-T1WI.

Conclusion

Vanishing of parotid tumors can be observed not only on FS-T2WI and FS-CE-T1WI but also on T2WI, CE-T1WI and ADC mapping.

Oncocytoma of the Deep Lobe of the Parotid Gland

BACKGROUND:

Oncocytoma or oxyphilic adenoma is uncommon salivary gland tumour, occurs predominantly in the in patients older than 60 years of age. Clinically oncocytoma resemble other salivary tumours while histology is typically consisting of oncocytes with many hyperplastic mitochondria. It usually occurs in the parotid gland. Because the features of oncocytoma are similar to those of other benign and low-grade malignant salivary tumours, clinical diagnosis is often challenging.

CASE PRESENTATION:

This report presents the pathologic and imaging findings of an oncocytoma arising in the deep lobe of the right parotid gland in a 74-year-old male. Oncocytoma was diagnosed on the basis of histological, magnetic resonance imaging (MRI), scintigraphic findings and fine needle aspiration cytology (FNAC).

CONCLUSION:

This case was unique because in the literature there are few articles about the rare presentation and deep lobe location of this type of parotid oncocytoma.