Multispectral optoacoustic tomography of benign parotid tumors in vivo: a prospective observational pilot study.

Parotid lumps are a heterogeneous group of mainly benign but also malignant tumors. Preoperative imaging does not allow a differentiation between tumor types. Multispectral optoacoustic tomography (MSOT) may improve the preoperative diagnostics. In this first prospective pilot trial the ability of MSOT to discriminate between the two most frequent benign parotid tumors, pleomorphic adenoma (PA) and Warthin tumor (WT) as well as to normal parotid tissue was explored. Six wavelengths (700, 730, 760, 800, 850, 900 nm) and the parameters deoxygenated (HbR), oxygenated (HbO2), total hemoglobin (HbT), and saturation of hemoglobin (sO2) were analyzed. Ten patients with PA and fourteen with WT were included (12/12 female/male; median age: 51 years). For PA, the mean values for all measured wave lengths as well as for the hemoglobin parameters were different for the tumors compared to the healthy parotid (all p < 0.05). The mean MSOT parameters were all significantly higher (all p < 0.05) in the WT compared to healthy parotid gland except for HbT and sO2. Comparing both tumors directly, the mean values of MSOT parameters were not different between PA and WT (all p > 0.05). Differences were seen for the maximal MSOT parameters. The maximal tumor values for 900 nm, HbR, HbT, and sO2 were lower in PA than in WT (all p < 0.05). This preliminary MSOT parotid tumor imaging study showed clear differences for PA or WT compared to healthy parotid tissue. Some MSOT characteristics of PA and WT were different but needed to be explored in larger studies.

High Intraepithelial Mast Cell Density in Warthin's Tumor.

BACKGROUND/AIM: Warthin's tumor, the second most frequent neoplasia of the parotid gland, is characterized by a proliferation of both epithelial and lymphoid components. In addition to epithelial and lymphoid cells, various other cell types are implicated to varying degrees in the immune response. Notably, mast cells have long been recognized as a consistent cell population within this tumor. Despite the historical acknowledgment of mast cell presence, their true distribution and significance within Warthin's tumor remain unclear. In this study, we aimed to elucidate the distribution and significance of mast cells in Warthin's tumor. MATERIALS AND METHODS: Histochemical and immunohistochemical methods were employed for the evaluation of mast cells within tumor specimens. RESULTS: Our study revealed a notable concentration of mast cells in the epithelial component of Warthin's tumor. Microscopic examination showed predominant lymphoid and epithelial elements with occasional cystic formations. Immunohistochemical analysis identified mast cells in both components, emphasizing their role in the tumor microenvironment. Double immunostaining (mast cell tryptase and CD34) revealed no significant correlation between mast cells and blood vessels. Intraepithelial mast cells (IEMCs) had a significantly higher density in the epithelial component, suggesting a potential association with the tumor's benign nature. The relationship between IEMCs and epithelial cells, especially in the presence of cystic structures, offers valuable insights into the unique features of Warthin's tumor. CONCLUSION: Our study contributes to the understanding of mast cells in Warthin's tumor, highlighting a substantial concentration within the epithelial component. This knowledge may pave the way for further investigations into the roles of mast cells in the pathogenesis and treatment of Warthin's tumor.

Clinical decision making when cytology indicates a Warthin tumor.

Warthin tumor (WT) is a benign tumor usually affecting the parotid gland. The main diagnostic tool remains ultrasound combined with fine-needle aspiration cytology (FNAC). This study aims to examine how reliably FNAC indicates WT for clinical decision making regarding surgical versus conservative management. We included all patients who underwent FNAC from a parotid gland lesion between 2016 and 2018 at our institution, and whose FNAC revealed WT suspicion. The FNACs were divided into three groups based on the cytology report: certain, likely, and possible WT. The patients were divided into two groups based on having had either surgery or follow-up. We sent a questionnaire to patients who had not undergone surgery in order to obtain follow-up for a minimum of four years. Altogether, 135 FNAC samples, from 133 tumors and 125 patients, showed signs of WT. Of the 125 patients, 44 (35%) underwent surgery, and 81 (65%) were managed conservatively. Preoperative misdiagnosis in FNAC occurred in three (7%) surgically treated tumors. Their FNACs were reported as possible WTs, but histopathology revealed another benign lesion. In the conservatively treated group, two patients underwent surgery later during the follow-up. Cytological statements of WT were seldom false, and none were malignant. The majority of the patients were only followed-up and rarely required further treatment. A certain or likely diagnosis of WT in the FNAC report by an experienced head and neck pathologist is highly reliable in selecting patients for conservative surveillance.

Differentiation of salivary gland tumours using diffusion-weighted image-based virtual MR elastography: a pilot study.

OBJECTIVES: Differentiation among benign salivary gland tumours, Warthin tumours (WTs), and malignant salivary gland tumours is crucial to treatment planning and predicting patient prognosis. However, differentiation of those tumours using imaging findings remains difficult. This study evaluated the usefulness of elasticity determined from diffusion-weighted image (DWI)-based virtual MR elastography (MRE) compared with conventional magnetic resonance imaging (MRI) findings in differentiating the tumours. METHODS: This study included 17 benign salivary gland tumours, 6 WTs, and 11 malignant salivary gland tumours scanned on neck MRI. The long and short diameters, T1 and T2 signal intensities, tumour margins, apparent diffusion coefficient (ADC) values, and elasticity from DWI-based virtual MRE of the tumours were evaluated. The interobserver agreement in measuring tumour elasticity and the receiver operating characteristic (ROC) curves were also assessed. RESULTS: The long and short diameters and the T1 and T2 signal intensities showed no significant difference among the 3 tumour groups. Tumour margins and the mean ADC values showed significant differences among some tumour groups. The elasticity from virtual MRE showed significant differences among all 3 tumour groups and the interobserver agreement was excellent. The area under the ROC curves of the elasticity were higher than those of tumour margins and mean ADC values. CONCLUSION: Elasticity values based on DWI-based virtual MRE of benign salivary gland tumours, WTs, and malignant salivary gland tumours were significantly different. The elasticity of WTs was the highest and that of benign tumours was the lowest. The elasticity from DWI-based virtual MRE may aid in the differential diagnosis of salivary gland tumours.

Oncocytoid Salivary Tumors: Differential Diagnosis and Utility of Newly Described Immunohistochemistry.

BACKGROUND: Oncocytoid salivary tumors include several entities such as oncocytoma, Warthin tumor, secretory carcinoma (SC), salivary duct carcinoma (SDC), acinic cell carcinoma (AciCC), oncocytic mucoepidermoid carcinoma (OMEC), intraductal carcinoma, and epithelial myoepithelial carcinoma (EMC). This review investigates the differential diagnosis of oncocytoid salivary tumors and explore the role of newly described immunostains as valuable tools for their diagnosing and potentially guiding treatment options. METHODS: We assess the utility of incorporating new immunohistochemical markers in routine practice to aid in diagnosing oncocytoid salivary tumors and potentially provide treatment options. RESULTS: In SDC, AR and Her2 immunostains are utilized as diagnostic tools and biomarkers for selecting patients who might benefit from Androgen-deprivation therapy (ADT) and HER2-targeted therapy. Furthermore, nuclear Pan-Trk immunostaining can aid in diagnosing SC. Additionally, NR4A3 immunostaining has been shown high sensitivity and specificity in identifying AciCC in both surgical and cytologic specimens. Similarly, RAS Q61R mutant-specific immunostaining, detected in EMC, may offer a cost-effective diagnostic marker for this tumor. Although further studies are required to evaluate the role of BSND, this marker has been reported to be positive in Warthin tumor and oncocytoma, aiding in differentiating them from other oncocytoid tumors, particularly OMEC. In addition, BRAFV600E mutant-specific immunostaining can serve as a diagnostic and potentially therapeutic marker for oncocytic intraductal carcinoma in mutation positive cases. CONCLUSION: Oncocytoid salivary tumors may have overlapping morphologies, posing diagnostic challenges for pathologists. Recently described immunohistochemical markers may offer valuable tools for diagnosing and potentially guiding treatment options for these tumors.

Differentiation of parotid pleomorphic adenoma from Warthin tumor using signal intensity ratios on fat-suppressed T2-weighted magnetic resonance imaging.

OBJECTIVE: To investigate the value of magnetic resonance imaging (MRI) signal intensity ratios (SIRs) based on fat-suppressed T2-weighted imaging (FS-T2WI), together with demographic features, MRI anatomical characteristics, and SIRs of histopathological patterns of the tumors, in the differentiation of parotid pleomorphic adenoma (PA) from Warthin tumor (WT). STUDY DESIGN: In total, 90 patients with PA and 56 patients with WT were enrolled in the study. SIRs of tumor to normal parotid gland (SIR-T/P), spinal cord (SIR-T/S), and muscle (SIR-T/M) were calculated. Demographic and radiological features of the 2-patient groups were compared with univariate analysis and multivariate logistic regression analysis. The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were analyzed to evaluate the utility of SIRs in distinguishing between PA and WT. RESULTS: SIR-T/P exhibited outstanding discriminating ability (AUC = 0.934), SIR-T/S had excellent discrimination (AUC = 0.839), and SIR-T/M showed acceptable discrimination (AUC = 0.728). When SIR-T/P of 1.96 was selected as the cutoff value, sensitivity and specificity were 0.756 and 0.982, respectively. SIR-T/P, age, sex, and number of lesions were identified as independent predictors by multivariate logistic regression analysis. Differences in SIRs between histopathological patterns were significant. CONCLUSION: SIR-T/P based on FS-T2WI is an effective discriminator in the differential diagnosis between PA and WT. Age, sex, and number of lesions provided additional value in differentiation.

Primary intranodal Warthin-like variant of mucoepidermoid carcinoma.

This report describes a rare case of primary intranodal Warthin-like mucoepidermoid carcinoma (WL-MEC) presenting as a left level II lymph node mass in a 48-year-old man. Warthin-like mucoepidermoid carcinoma is a recently defined variant of MEC that bears a close histologic resemblance to Warthin tumor. Whereas MEC has readily identifiable key histologic features that render diagnosis relatively straightforward, WL-MEC is a challenging diagnosis due to overlapping histologic features and only limited case reports in the literature. This case was initially diagnosed as primary intranodal MEC after the exclusion of metastasis by imaging. It was not until years later, upon review of historic cases, that the diagnosis of WL-MEC was established. This diagnosis was further supported by molecular testing that was not available at the time of the original diagnosis.

Growth rates over time of unoperated parotid benign tumors.

INTRODUCTION: The treatment of parotid benign tumor is in principle surgery, but observation may be necessary in some cases. The purpose of this study was to investigate the growth rates over time of unoperated parotid benign tumors. METHODS: We retrospectively reviewed the medical records of 63 patients with unoperated parotid benign tumors diagnosed at our institution between January 2010 and December 2022. RESULTS: Forty-nine of the 63 patients had a Warthin tumor and 13 patients had a pleomorphic adenoma. On average, the unoperated parotid benign tumors grew 0.02 cm in length and 0.4 cm3 in volume per year. Compared to pleomorphic adenomas, Warthin tumors were more predominant in male patients and in those with a smoking history and a longer duration of smoking history; patients with Warthin tumors were also followed up longer (p < 0.05). However, the length and volume growth rates of unoperated Warthin tumors and pleomorphic adenomas did not significantly differ. CONCLUSION: Surgery is the standard treatment for parotid benign tumors. However, small benign parotid tumors identified during preoperative examination can be observed through close follow-up, taking into account the patient's medical and general condition.

Bilateral intra-lymph node Warthin's tumor as a potential diagnostic pitfall mimicking metastatic carcinoma.

Warthin's tumor (WT) is a benign and frequent salivary gland tumor primarily affecting the parotid gland. In some cases, this tumor can involve the extra parotid region and affect cervical lymph nodes. Fine-needle aspiration can be the first step in the diagnostic approach to lymphadenopathy; however, specimens from intra-nodal WT can present a potential pitfall, leading to a misdiagnosis of metastasis. Here, we report an unusual case of a patient with bilateral WT in parotid lymph nodes misdiagnosed as metastases. In addition, we highlight the cytopathological aspects of WT to alert cytopathologists about this challenging diagnosis.

Keratocystoma: A Distinctive Salivary Gland Neoplasm Characterized by RUNX2 Rearrangements.

Keratocystoma is a rare salivary gland lesion that has been reported primarily in children and young adults. Because of a scarcity of reported cases, very little is known about it, including its molecular underpinnings, biological potential, and histologic spectrum. Purported to be a benign neoplasm, keratocystoma bears a striking histologic resemblance to benign lesions like metaplastic Warthin tumor on one end of the spectrum and squamous cell carcinoma on the other end. This overlap can cause diagnostic confusion, and it raises questions about the boundaries and definition of keratocystoma as an entity. This study seeks to utilize molecular tools to evaluate the pathogenesis of keratocystoma as well as its relationship with its histologic mimics. On the basis of targeted RNA sequencing (RNA-seq) results on a sentinel case, RUNX2 break-apart fluorescence in situ hybridization (FISH) was successfully performed on 4 cases diagnosed as keratocystoma, as well as 13 cases originally diagnosed as tumors that morphologically resemble keratocystoma: 6 primary squamous cell carcinomas, 3 metaplastic/dysplastic Warthin tumors, 2 atypical squamous cysts, 1 proliferating trichilemmal tumor, and 1 cystadenoma. RNA-seq and/or reverse transcriptase-PCR were attempted on all FISH-positive cases. Seven cases were positive for RUNX2 rearrangement, including 3 of 4 tumors originally called keratocystoma, 2 of 2 called atypical squamous cyst, 1 of 1 called proliferating trichilemmal tumor, and 1 of 6 called squamous cell carcinoma. RNA-seq and/or reverse transcriptase-PCR identified IRF2BP2::RUNX2 in 6 of 7 cases; for the remaining case, the partner remains unknown. The cases positive for RUNX2 rearrangement arose in the parotid glands of 4 females and 3 males, ranging from 8 to 63 years old (mean, 25.4 years; median, 15 years). The RUNX2 -rearranged cases had a consistent histologic appearance: variably sized cysts lined by keratinizing squamous epithelium, plus scattered irregular squamous nests, with essentially no cellular atypia or mitotic activity. The background was fibrotic, often with patchy chronic inflammation and/or giant cell reaction. One case originally called squamous cell carcinoma was virtually identical to the other cases, except for a single focus of small nerve invasion. The FISH-negative case that was originally called keratocystoma had focal cuboidal and mucinous epithelium, which was not found in any FISH-positive cases. The tumors with RUNX2 rearrangement were all treated with surgery only, and for the 5 patients with follow-up, there were no recurrences or metastases (1 to 120 months), even for the case with perineural invasion. Our findings solidify that keratocystoma is a cystic neoplastic entity, one which appears to consistently harbor RUNX2 rearrangements, particularly IRF2BP2::RUNX2 . Having a diagnostic genetic marker now allows for a complete understanding of this rare tumor. They arise in the parotid gland and affect a wide age range. Keratocystoma has a consistent morphologic appearance, which includes large squamous-lined cysts that mimic benign processes like metaplastic Warthin tumor and also small, irregular nests that mimic squamous cell carcinoma. Indeed, RUNX2 analysis has considerable promise for resolving these differential diagnoses. Given that one RUNX2 -rearranged tumor had focal perineural invasion, it is unclear whether that finding is within the spectrum of keratocystoma or whether it could represent malignant transformation. Most important, all RUNX2 -rearranged cases behaved in a benign manner.

Surgical management of Warthin tumor: long-term follow-up of 224 patients from 2002 to 2018.

PURPOSE: Warthin tumors (WT) are the second most common benign parotid gland neoplasms. They can occur as synchronous or metachronous lesions in 6-10% of cases. This study aims to compare the complication rate in 224 patients who underwent extracapsular dissection (ECD) or superficial parotidectomy (SP) for the treatment of a WT. METHODS: This retrospective study was conducted at the Department of Maxillo-Facial Surgery at the University of Naples "Federico II" from February 2002 to December 2018 on a group of patients who underwent surgical treatment for WT. The type of surgical technique was chosen based on Quer's classification. The complications evaluated were facial nerve palsy, hematoma, Frey's syndrome, and bleeding. RESULTS: A total of 224 patients treated from 2002 to 2018 for Warthin tumor were included in the study. Two hundred elven had solitary tumors (94.1%) and 13 had multicentric lesions (5.8%), of which 9 cases presented synchronous lesions and 4 cases presented metachronous lesions. Extracapsular dissection (ECD) was performed in 130 patients (58.3% of cases) and superficial parotidectomy (SP) in the other 94 (41.7% of cases). CONCLUSIONS: We consider both surgical techniques as valid. In our opinion, it is essential to study each case based on Quer's Classification to obtain the best surgical outcome. Based on a lower observed rate of complications such as facial nerve palsy, Frey's syndrome, and bleeding, ECD seems to be the best option for the surgical treatment of Quer Class I lesions.

A Safety and Feasibility Trial of Ultrasound-Guided Radiofrequency Ablation of Parotid Warthin's Tumor.

OBJECTIVE: To determine if ultrasound-guided (USG) radiofrequency ablation (RFA) of Parotid Warthin's tumor under local anesthesia is a safe and effective procedure. STUDY DESIGN: Safety and feasibility study. SETTING: Tertiary academic medical center. METHODS: This is an IDEAL phase 2a trial in a tertiary referral center. Twenty patients with Parotid Warthin's tumor were recruited. RFA was done between September and December 2021 for all 20 patients using a CoATherm AK-F200 machine with a disposable, 18G × 7 mm radiofrequency electrode. Results and follow-up statistics were compared with a historic sample of patients with parotid Warthin's tumor who underwent parotidectomy between 2019 and 2021 in the same center. RESULTS: Nineteen patients were included in the analysis as 1 patient dropped out after 4 weeks of follow-up. The mean age for the RFA group was 67 years old with most of them being male smokers. At a median of 45 weeks (44-47 weeks) postprocedure there was a 7.48 mL (68.4%) volume reduction compared to baseline. Three patients had transient facial nerve (FN) paresis, 1 recovered within hours, and the other 2 by 12 weeks follow-up. Three patients had great auricular nerve numbness; 1 patient had infected hematoma treated in an out-patient manner. Compared to a historic cohort of parotidectomy patients for Warthin's tumor, there was no significant difference in FN paresis and other minor complications between the 2 treatment modalities. CONCLUSION: The current analysis suggests that USG RFA of Warthin's Tumor is a safe alternative to parotidectomy with shorter operative time and length of stay.

Salivary Duct Carcinoma Arising in a Warthin Tumor of the Parotid Gland: A Rare Case Report with Review of Literature and PD-L1 Expression.

Warthin's tumor is the second most common neoplasm of the parotid gland and consists of 2 components, including lymphoid stroma and glandular epithelium. Malignant transformation in this tumor is mostly seen in the lymphoid component; however, the carcinomatous transformation of the epithelial component is extremely rare. Cases of latter reported in the literature include squamous cell carcinoma, adenocarcinoma, mucoepidermoid carcinoma, oncocytic carcinoma, Merkel cell carcinoma, and undifferentiated carcinoma. We describe an extremely rare case of salivary duct carcinoma arising in a Warthin tumor in a 64-year-old male. Patient presented with an enlarging left parotid mass, biopsy of which showed salivary duct carcinoma. He subsequently underwent left parotidectomy along with left level II-IV lymph node dissection. Histology revealed both in situ as well as invasive salivary duct carcinoma arising from Warthin tumor. Immunohistochemistry showed tumor cells positive for CK7, AR, and GATA3, while p63 highlighted the myoepithelial cell layer in the in situ component. Her2 was 2+ by immunohistochemistry. In addition, PD-L1 IHC revealed positive expression with a combined positive score of 20%.

Warthin-like mucoepidermoid carcinoma of the parotid gland: Clinicopathological observation and literature review.

Warthin tumor (WT)-like mucoepidermoid carcinoma resembles the histologic pattern of WT and pathologists unaware of this possibility may misdiagnose it as WT with squamous and mucous epithelium metaplasia or WT malignant transfer into mucoepidermoid carcinoma. The present study reported a case of a 41-year-old Chinese female with a solitary mass in the left parotid gland. In this case, microscopic observation revealed prominent lymph node stroma and multiple cystic structures similar to those seen in WT. However, it lacked the two layers of oncocytic epithelial tissue characteristic of WT. Furthermore, fluorescence in situ hybridization detected MAML2 rearrangement in the case. Considering the histological findings, this case was diagnosed as WT-like mucoepidermoid carcinoma. The present case report provides pathological and clinical features to differentiate it from WT malignant transition into mucoepidermoid carcinoma, WT with squamous and mucous epithelium metaplasia and non-sebaceous lymphadenoma-like mucoepidermoid carcinoma. In conclusion, WT-like mucoepidermoid carcinoma as a special subtype of mucoepidermoid carcinoma has special histological characteristics, which required further observations and more case reports to clearly define this variant.

Warthin Tumor of the Parotid Gland: The History of an Eponym.

The eponymous history of Warthin tumor (WT) is a fascinating issue in the field of salivary gland pathology. The late decades of the nineteenth century and the turn of the century saw notable German and French contributions on WT. Especially, the seminal 1910 paper of Albrecht and Arzt of Vienna is the foundation for the current knowledge of WT. It is generally believed that prior to this pioneering study, Hildebrand of Göttingen accurately described the lesion of WT in 1895. However, the historical origins of WT appear to be unsettled, and only a few German pathologists and surgeons are aware that dating back to 1885, the first recognizable reference to WT was that by the renowned German-Swiss pathologist Zahn, whose name is eponymously associated with "Zahn infarct" and "lines of Zahn". Two noted French surgeons with a major interest in pathology, Albarrán in 1885 and Lecéne in 1908, did not contribute to the topic. Since the 1950s, a mostly American group of pathologists and surgeons gradually adopted the term WT to replace the very accurate histologic descriptor "papillary cystadenoma lymphomatosum" coined by Warthin himself in 1929. It is our opinion that from a historical viewpoint, there is no particular reason why this tumor should have been named WT.

Warthin-like papillary carcinoma: Case report.

Warthin-like papillary thyroid carcinoma is a rare variant of papillary carcinoma with a very good prognosis. It is often associated with lymphocytic thyroiditis. Due to its typical histological picture resembling Warthin's salivary gland tumor, the histological diagnosis is not difficult, usually does not require an accompanying immunohistochemical examination and is based on the presence of nuclear features typical of papillary carcinoma and the presence of oncocytes in a background of rich lymphocyte infiltrate. The preoperative cytologic examination is challenging, as many other lesions may have a similar picture. Women are more likely to get affected. It appears a decade earlier than the classic variant. Clinically, it presents similarly to a conventional papillary carcinoma. In our case report, we would like to present the case of a 56-year-old woman with non-toxic multinodular goiter, in whom the presence of this rare variant of papillary carcinoma was revealed by histological examination.

Top Ten Oncocytic Head and Neck Lesions to Contemplate.

BACKGROUND: Oncocytes are a component of many metaplastic and neoplastic lesions throughout the head and neck area, primarily originating in salivary/seromucinous glands and the thyroid gland. In addition, other lesions can contain cells that mimic oncocytes (pseudo-oncocytes); these can be of epithelial or non-epithelial origin. METHODS: Review article. RESULTS: Oncocytic metaplasia is common in seromucinous glands throughout the upper aerodigestive tract, most notable in the oral cavity, nasopharynx and larynx. The main oncocytic salivary gland neoplasms are Warthin tumor and oncocytoma. Infarction of Warthin tumor may lead to recognition difficulties. Oncocytic subtypes of mucoepidermoid carcinoma and intraductal carcinoma have morphologic and immunohistochemical features that allow distinction from major oncocytic entities. Oncocytic thyroid tumors include adenoma, carcinoma (follicular, papillary and medullary), along with poorly differentiated tumors. Oncocytic papillary sinonasal and middle ear tumors must be distinguished from low grade adenocarcinomas. Pseudo-oncocytic entities include paraganglioma, Langerhans cell histiocytosis, giant cell tumor, rhabdomyoma, and metastatic tumors. CONCLUSIONS: Correct diagnosis of oncocytic head and neck lesions requires a knowledge of the spectrum of possible entities, their characteristic sites of occurrence, architecture, histomorphology, and immunohistochemistry. Oncocytic subtypes of several newly described entities are now recognized. Both epithelial and non-epithelial mimics of oncocytes exist. The molecular features of oncocytic tumors can be helpful in their diagnosis and understanding their pathogenesis.

Validation of indications for enucleation for benign parotid gland tumors.

BACKGROUND: Enucleation has been reported as a minimally invasive surgery for Warthin's tumor (WT). However, the definite indications for enucleation have not been clarified. METHODS: Enucleation was indicated by the following findings: findings of WT, cystic fluid, or benign leukocytes by fine-needle aspiration cytology; a well-margined and homogeneous pattern on imaging; and a tumor location in the tail or preauricular area of the parotid gland. We reviewed 552 cases treated with parotid gland surgery in our hospital. RESULTS: A total of 108 tumors were treated with enucleation and included no malignant solid tumors or pleomorphic adenoma. Enucleation demonstrated low invasiveness and complication rates. Revision surgery for WT reappearance after enucleation was rare and showed minimal scarring, with a lower risk of facial weakness. CONCLUSIONS: The indication criteria for enucleation were validated. Such enucleation is useful, as it is associated with minimal invasiveness, low complication rates, and safety in revision surgery.