CT Features of Parotid Gland Oncocytomas: A Study of 10 Cases and Literature Review

Abstract

SUMMARY: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-radiologicpathologic 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.O ncocytomas of the salivary gland, which were first described by Jaffé in 1932, are benign epithelial tumors that occur most commonly in adults in their sixth to eighth decades, [1][2][3][4][5][6] with no clear sex predilection. 3,4,[6][7][8][9] These neoplasms are histologically composed of monotonous sheets of oncocytes, epithelial cells named by Hamperl in 1931, which are characterized by an intensely eosinophilic and granular cytoplasm. These metabolically altered epithelial cells accumulate numerous cytoplasmic mitochondria through the process of oncocytic metaplasia. 1,4,5,7,[10][11][12] Synonyms for this tumor include oncocytic adenoma, oxyphilic granular-cell adenoma, and oxyphilic adenoma.Oncocytomas are rare, comprising just 0.5%-1.5% of salivary gland tumors. 4,[7][8][9][13][14][15][16] The parotid gland is the most commonly involved salivary gland, accounting for 78%-84% of salivary gland oncocytomas.2,3 Oncocytomas occurring in the submandibular gland and the minor salivary glands have been reported but are relatively uncommon. 2,7,9 CT is one of the established first-line imaging modalities used in the assessment of major salivary gland tumors. 2,17,18 To the authors' knowledge, there is limited description of the CT imaging features of parotid gland oncocytomas in the published literature, apart from a few case reports. 15,16,[19][20][21] Because the surgical resection of parotid tumors is generally the treatment of choice and allows histopathologic confirmation, the identification of specific CT imaging features suggestive of benign parotid oncocytomas will become helpful in terms of simply managing the patient expectantly when certain clinical scenarios arise-for example, if the patient declines surgical intervention, when patient factors such as age and multiple comorbidities preclude surgical resection, or when biopsy results are not diagnostic. In this study, we describe the CT features of 10 histopathologically proved cases of parotid oncocytomas, the largest imaging series in the published literature, to our knowledge. Materials and MethodsA review of parotid tumors that were discussed at combined clinicalradiologic-...

Oncocytoma of the Parotid Gland:A Case Report and Review of the Literature

“…Oncocytomas are rare tumors that constitute 0.1–1.5% of salivary gland tumors [4, 6, 7, 8] and only 2.3% of benign epithelial salivary gland neoplasms [5]. Oncocytomas were first described by Jaffé in 1932 [see reference 6].…”

“…Oncocytomas were first described by Jaffé in 1932 [see reference 6]. The parotid gland is the most commonly involved organ accounting for 78–84% of salivary gland oncocytomas [6]. Oncocytomas are benign epithelial tumors characterized by oncocytes with eosinophilic granular cytoplasm rich in mitochondria [3, 4, 9].…”

“…Oncocytic cells are thought to originate from the transformation of epithelial cells of salivary gland ducts or acini [10]. They occur most commonly in their sixth to eighth decades and are slightly predominant in women [6, 11]. …”

“…They are firm, may be multilobulated and mobile on examination [6, 12]. They are classified according to the new World Health Organization (WHO) classification, and histologically there are three distinct types, namely oncocytosis, oncocytoma and oncocytic carcinoma [2].…”

“…CT has been established as the first-line image modality in the assessment of major salivary gland tumors [6]. Oncocytomas and Warthin's tumors have very similar imaging features; thus, they are indistinguishable in standard CT and MR images [13].…”