Oncocytic carcinoma of the accessory lobe of the parotid gland

Rationale for Increasing Oncological Vigilance in Relation to Clinical Findings in Accessory Parotid Gland-Observations Based on 2192 Cases of the Polish Salivary Network Database

The accessory parotid gland (APG, Vth level) differs in histological structure from main parotid tissue. This gives rise to the hypothesis, mirrored in clinical observations, that the representation of tumours is different than in the rest of the gland. The aim of the study was to analyse the epidemiological and histological differences of parotid tumours located in regions I-V, with particular emphasis on the distinctiveness of region V. To define the epidemiological factors that will indicate the risk of histological malignancy from clinically benign appearance, multicentre prospective studies conducted between 2017-2021 by five Head and Neck Surgery University Departments, cooperating within the Polish Salivary Network Database 1929 patients (1048 women and 881 men), were included. The age, gender, patient occupation, place of inhabitation, tumour size, clinical features of malignancy, histology, and facial nerve (FN) paresis were analysed for superficial (I_II) and deep (III_IV) lobes and with special regard to the tumours affecting region V. Twenty eight tumours were located exclusively in region V (1.45% total) and seventy-two tumours were found in region V exhibiting extensions to neighbouring regions (3.7% total), characterised as significantly younger and less frequent in retirees. In I-IV regions, approximately 90% of tumours were benign, with pleomorphic adenoma (PA) and Whartin tumour (WT) predominance. In region V, PA exceeded 75% but WT were casuistic (2/28). Incidences of malignancies in region V was 40% but clinical signs of malignancy were evident only in tumours > 4 cm or in the presence of FN paresis. In 19% of patients with a benign appearance, imaging revealed malignancy; however, 38% of patients showed false negative results both in terms of clinical and radiological features of malignancy. Logistic regression models in 28 patients with tumours located exclusively in region V vs. 1901 other patients and in 100 patients with V extension vs. 1829 other patients showed no clinical symptoms of malignancy binding with final malignant tumour histology as a single variable or in combination with other variables. The logistic regression models obtained in this study show strong linkage between tumour location and predictors (age, male gender, and tumour diameter) and also aimed to function as a good classifier. Our conclusion is that, despite the very clear image of the mid-cheek tumour which is easily accessible in palpation and ultrasound examination, it is necessary to improve oncological vigilance and preoperative patient preparation.

The key radiologic and cytomorphologic features of oncocytic and oncocytoid lesions of the salivary gland

Oncocytic and oncocytoid lesions represent a distinct subset of salivary gland lesions. True oncocytic lesions of the salivary gland are entirely composed of oncocytes. These are characterized by the presence of abundant eosinophilic granules due to the presence of abundant cytoplasmic mitochondria. Oncocytic lesions of the salivary gland include oncocytosis, oncocytoma, and oncocytic carcinoma. In addition to the true oncocytic lesion, there exists another group of salivary gland lesions, which demonstrate cells with abundant and occasionally granular cytoplasm. These are often termed as "oncocytoid" lesions. The recently proposed Milan System for reporting salivary gland cytology clearly states that fine-needle aspiration specimens representing oncocytic/oncocytoid lesions of salivary gland cannot effectively distinguish between a nonneoplastic lesion, benign and malignant neoplasms. Therefore, most lesions lacking classic cytomorphologic features will be classified under the umbrella diagnostic term of "Salivary Gland Neoplasm of Uncertain Malignant Potential" (SUMP). In this review, we discuss and illustrate key clinicopathologic and radiologic features that can help the practicing cytopathologist narrow down the differential and provide the best management based diagnosis.

Management of accessory parotid gland tumours: 32-year experience from a single institution and review of the literature

Accessory parotid gland tumours (APGTs) are very rare. Regarding their anatomical location, an adequate surgical approach is necessary to provide safe resection and satisfactory postoperative results. The aims of this study were to present our tertiary centre experience in surgical treatment and management of APGTs and to review the literature regarding their treatment, particularly in terms of surgical modalities. Data of 13 patients with primarily surgically treated APGTs have been collected and analysed. Well-documented English-literature articles of surgically treated APGTs have been extracted from the PubMed, Scopus and Web of Science databases ending in May 2018, and analysed. Mean age at diagnosis was 41.1 years. The most common benign histological subtype was pleomorphic adenoma (53.8%), while mucoepidermoid carcinoma (23.1%) was most common in malignant counterparts. The malignancy rate was 38.5%. Postoperative results were satisfactory, and the follow-up period was uneventful in all patients except one who died of locoregional recurrence. A total of 57 papers with reported series in APGTs have been identified with a total of 306 APGT cases. From oncological, functional and aesthetic standpoints, approaches through a standard parotidectomy provide satisfactory results.

An invasive adenocarcinoma of the accessory parotid gland: a rare example developing from a low-grade cribriform cystadenocarcinoma?

Low-grade cribriform cystadenocarcinoma (LGCCA) is a rare tumor of the salivary gland that exhibits clinically indolent behavior. In this paper, we present a case of invasive adenocarcinoma of the accessory parotid gland in a young male that exhibited histology suggestive of an association of LGCCA. A 27-year-old man presented with a subcutaneous tumor in his left cheek. The tumor was separated from the parotid gland and located on the masseter muscle. The tumor was resected, and the postoperative histological diagnosis was adenocarcinoma, not otherwise specified (ANOS). The tumor exhibited papillary-cystic and cribriform proliferation of the duct epithelium and obvious stromal infiltration. Some tumor nests were rimmed by myoepithelium positive for smooth muscle actin, p63, and cytokeratin 14, indicating the presence of intraductal components of the tumor. Tumor cells exhibited mild nuclear atypia, and some of them presented an apocrine-like appearance and had cytoplasmic PAS-positive/diastase-resistant granules and hemosiderin. Other cells had foamy cytoplasm with microvacuoles. Immunohistochemistry revealed that the almost all of the tumor cells were strongly positive for S-100. These histological findings suggest the possibility that ANOS might arise secondarily from LGCCA. This is an interesting case regarding the association between ANOS and LGCCA in oncogenesis.