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.

Lymphoma presenting as preauricular tumor in unilateral parotid gland agenesis: a case report and review of literature.

BACKGROUND: Parotid gland agenesis is a rare, congenital, usually asymptomatic disorder. Until now, only 24 cases with unilateral, incidentally found, parotid gland agenesis have been described. Here, we present the first reported case of an ipsilateral preauricular neoplasm in a patient with unilateral parotid gland agenesis. During surgery, the position of the greater auricular- and facial nerves was documented. Furthermore, we performed the first sialendoscopy for this rare disorder to assess the number of duct branches, which might be indicative of the abundance of parotid tissue. Moreover, we looked for sialendoscopic characteristic features that could aid in identifying these patients in the ambulatory setting. CASE PRESENTATION: A 50-year-old Greek man presented with a painless, slowly enlarging mass in the right parotid space. Magnetic resonance imaging revealed a complete absence of the right parotid gland without accessory parotid tissue. The right parotid gland was replaced by fatty tissue and the radiologist suggested a benign parotid tumor. Fine needle aspiration was indicative of a reactive lymph node. Sialendoscopy revealed only two branches within the right parotid duct. Surgical resection was performed through a conventional lateral parotidectomy. This revealed typical anatomic position of the greater auricular- and facial nerves despite the parotid tissue agenesis. Histopathology revealed a small lymphocytic lymphoma. CONCLUSIONS: Surgeons should feel confident to resect tumors of the parotid space in patients with parotid gland agenesis. Reduced branching observed during sialendoscopy might indicate parotid gland agenesis. Physicians should be even more cautious than usual with the watch and wait strategy in patients with tumors of parotid gland agenesis, since the probability of a tumor being a benign salivary gland tumor might be lower than usual.

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.

Basal cell adenoma and basal cell adenocarcinoma of the parotid gland: clinical findings and surgical outcomes in a single-institution study.

BACKGROUND: Basal cell adenoma (BCA) is a rare benign tumor within the salivary glands. Basal cell adenocarcinoma (BCAC), the malignant counterpart of BCA, is also an exceedingly rare tumor with very limited clinical studies conducted. This study aims to investigate the clinical characteristics, demographics, and surgical outcomes of patients diagnosed with BCA and BCAC within the parotid gland. METHODS: A retrospective analysis from May 2003 to August 2023 was performed for all patients undergoing parotidectomy for masses. Retrospective data on gender, age, tumor characteristics, and outcomes were collected. Surgical approaches, including negative margin attainment, capsule removal, and histological diagnosis, were also detailed. RESULTS: The study included 1268 patients who underwent parotidectomy, resulting in 81 cases of BCA and 7 cases of BCAC. BCA patients, with a mean age of 55.1 years, showed diverse age distribution and predominantly presented in the 50s. In BCAC cases, seven female patients exhibited a predominant location in the deep lobes. FNA revealed BCAC in three out of seven cases, and subsequent parotidectomy was performed, resulting in no observed recurrences or metastases. CONCLUSION: This study reports the largest number of BCA cases from a single institution and provides comprehensive insights into the demographics, tumor characteristics, and clinical outcomes of both BCA and BCAC. Although further research should be conducted, based on clinical follow-up results, appropriately including the capsule in the tumor excision indicates favorable outcomes, especially when the tumor size is not large.

Chinese surgical robot-assisted surgery for parotid tumor: a case report.

Robotic surgery is known as the "third technological revolution" in the field of surgery, and is an important milestone in the development of modern surgery. However, our country's innovative surgical robot industry is still in its early stages, and it is only being utilized in certain surgical fields. To explore the effectiveness of the application of domestic surgical robot in oral and maxillofacial surgery, the author successfully completed a case of benign parotid tumor resection with the assistance of a domestic autonomous robot. The operation was successful, facial nerve function was preserved, and postoperative wound healing was good.

Unicentric Castleman's disease in the parotid gland associated with psoriasis: a case report.

BACKGROUND: Castleman's disease is a rare lymphoproliferative disorder that is often misdiagnosed because of its untypical clinical or imaging features except for a painless mass. Besides, it is also difficult to cure Castleman's disease due to its unclear pathogenesis. CASE PRESENTATION: We present a Castleman's disease case with diagnostic significance regarding a 54-year-old Chinese male who has a painless mass in his left parotid gland for 18 months with a 30-years history of autoimmune disease psoriasis. Computed tomography scan showed a high-density nodule with clear boundaries in the left parotid and multiple enlarged lymph nodes in the left submandibular and neck region. General checkup, the extremely elevated serum interleukin-6 and lymph node biopsy in the left submandibular region gave us an initial suspicion of Castleman's disease. Then the patient underwent a left superficial parotidectomy. Based on histopathologic analysis, we made a certain diagnosis of Castleman's disease and gave corresponding treatments. In 18 months of follow-up, the patient showed no evidence of recurrence, with the level of serum interleukin-6 decreased. CONCLUSIONS: Clinicians should be aware of the possibility of Castleman's disease when faced with masses or enlarged lymph nodes in the parotid gland to avoid misdiagnosis, especially in patients with autoimmune diseases and elevated serum interleukin-6.

Deep learning for the automatic detection and segmentation of parotid gland tumors on MRI.

OBJECTIVES: Parotid gland tumors (PGTs) often occur as incidental findings on magnetic resonance images (MRI) that may be overlooked. This study aimed to construct and validate a deep learning model to automatically identify parotid glands (PGs) with a PGT from normal PGs, and in those with a PGT to segment the tumor. MATERIALS AND METHODS: The nnUNet combined with a PG-specific post-processing procedure was used to develop the deep learning model trained on T1-weighed images (T1WI) in 311 patients (180 PGs with tumors and 442 normal PGs) and fat-suppressed (FS)-T2WI in 257 patients (125 PGs with tumors and 389 normal PGs), for detecting and segmenting PGTs with five-fold cross-validation. Additional validation set separated by time, comprising T1WI in 34 and FS-T2WI in 41 patients, was used to validate the model performance. RESULTS AND CONCLUSION: To identify PGs with tumors from normal PGs, using combined T1WI and FS-T2WI, the deep learning model achieved an accuracy, sensitivity and specificity of 98.2% (497/506), 100% (119/119) and 97.7% (378/387), respectively, in the cross-validation set and 98.5% (67/68), 100% (20/20) and 97.9% (47/48), respectively, in the validation set. For patients with PGTs, automatic segmentation of PGTs on T1WI and FS-T2WI achieved mean dice coefficients of 86.1% and 84.2%, respectively, in the cross-validation set, and of 85.9% and 81.0%, respectively, in the validation set. The proposed deep learning model may assist the detection and segmentation of PGTs and, by acting as a second pair of eyes, ensure that incidentally detected PGTs on MRI are not missed.

Metastasizing pleomorphic adenoma of the parotid gland: A common tumour with a very unusual presentation.

Metastasizing pleomorphic adenoma is recognized as a subtype of pleomorphic adenoma in WHO classification 5th edition of salivary glands. The controversy pertaining to the entity is the benign features of the disease even at a metastatic site. We present a rare case of left recurrent pre-auricular swelling in a young male reported as metastasizing pleomorphic adenoma. A nineteen-year-old male presented with left preauricular swelling seven years ago which was diagnosed as pleomorphic adenoma and underwent complete excision of tumour. The tumour recurred twice - two and five years after the surgery. At the second recurrence, the level II neck dissection showed multiple encapsulated deposits of pleomorphic adenoma having similar morphology in the cervical soft tissue with no features of high-grade transformation.

[Diffuse thickening of bronchial walls with multiple nodular mucosal protrusions].

A 58-year-old woman presented with a six-month history of nasal congestion, sore throat and cough, and a five-month history of dyspnea. She had a history of xerostomia for one year. On examination, the bilateral submandibular gland and parotid glands were enlarged. Parotid and anterior cervical lymph nodes were palpable. There were rales in both lungs. The rest of the physical examination was unremarkable. Sialographic analysis showed normal caliber in the main duct, stenosis in secondary ducts, and dilation in the proximal ducts. Minor salivary gland biopsy demonstrated periductal lymphocytic infiltration. Chest computed tomography (CT) showed diffuse thickening of the tracheal and bilateral bronchial walls. Bronchoscopy revealed macroscopic multiple nodules mainly in the trachea and bilateral main bronchus. Endobronchial biopsy showed lymphocytic infiltration in the bronchial submucosa. She was diagnosed with Sjögren's syndrome and treated with glucocorticoids. The dose of prednisone was started at 30 mg/d and tapered gradually. Following treatment, the patient's clinical condition improved dramatically, with shrinkage of the enlarged lymph nodes, bilateral submandibular and parotid glands. A repeated chest CT scan revealed improvement of the tracheal and bilateral bronchial thickening. Multiple nodules in the airway regressed, as evidenced by repeated bronchoscopic examination. The final diagnosis was a large-airway disease associated with Sjögren's syndrome.Among airway diseases in Sjögren's syndrome, peripheral airway diseases including bronchiolitis and bronchiectasis are common; however, central airway lesions in Sjögren's syndrome, especially with macroscopic nodules, are rare. In this case, we demonstrated tracheal and endobronchial nodules in Sjögren's syndrome as determined by clinical features, CT scan, bronchoscopy, and response to therapy.

Parotid Gland Cancer With First Bite Syndrome Detected via CT-Guided Fine Needle Aspiration Cytology.

BACKGROUND/AIM: First bite syndrome (FBS) is a symptom of severe pain at the beginning of a meal that lessens as the meal progresses. It is a common postoperative complication of parapharyngeal space tumors and is rarely reported as the first symptom of parotid carcinoma. The parapharyngeal space is considered a difficult area for approach; hence, preoperative histopathology is often challenging. However, there are hardly any reports on the approach of performing biopsies under computerized tomography (CT) guidance. CASE REPORT: A 28-year-old woman presented to our hospital with the chief complaint of pain in the left parotid region since the past year. Contrast-enhanced magnetic resonance imaging of the parotid gland revealed a 10-mm high-signal area on T2-weighted images extending from the deep lobe of the left parotid gland to the parapharyngeal space, which could not be visualized on ultrasound. She was suspected to have a malignant tumor because of the presence of a parotid tumor with FBS. Therefore, she underwent CT-guided fine-needle aspiration cytology (FNAC) and was diagnosed with adenoid cystic carcinoma. The patient underwent left parotid tumor resection and left cervical dissection, and her pain during feeding improved postoperatively. CONCLUSION: In a patient with parotid tumor extending into the parapharyngeal space with FBS as the initial symptom, CT-guided FNAC was successfully used to diagnose parotid carcinoma. Symptoms of pain, including FBS, should be considered in cases of malignancy. CT-guided FNAC is effective for lesions that cannot be visualized by ultrasound, such as those in the parapharyngeal space.

Characterization of parotid gland tumors using diffusion-relaxation correlation spectrum imaging: a preliminary study.

AIM: To assess the performance of diffusion-relaxation correlation spectrum imaging (DR-CSI) in the characterization of parotid gland tumors. MATERIALS AND METHODS: Twenty-five pleomorphic adenomas (PA) patients, 9 Warthin's tumors (WT) patients and 7 malignant tumors (MT) patients were prospectively recruited. DR-CSI (7 b-values combined with 5 TEs, totally 35 diffusion-weighted images) was scanned for pre-treatment assessment. Diffusion (D)-T2 signal spectrum summating all voxels were built for each patient, characterized by D-axis with range 0∼5 × 10-3 mm2/s, and T2-axis with range 0∼300ms. With boundaries of 0.5 and 2.5 × 10-3 mm2/s for D, all spectra were divided into three compartments labeled A (low D), B (mediate D) and C (high D). Volume fractions acquired from each compartment (VA, VB, VC) were compared among PA, WT and MT. Diagnostic performance was assessed using receiver operating characteristic analysis and area under the curve (AUC). RESULTS: Each subtype of parotid tumors had their specific D-T2 spectrum. PA showed significantly lower VA (8.85 ± 4.77% vs 20.68 ± 10.85%), higher VB (63.40 ± 8.18% vs 43.05 ± 7.16%), and lower VC (27.75 ± 8.51% vs 36.27 ± 11.09) than WT (all p<0.05). VB showed optimal diagnostic performance (AUC 0.969, sensitivity 92.00%, specificity 100.00%). MT showed significantly higher VA (21.23 ± 12.36%), lower VB (37.09 ± 6.43%), and higher VC (41.68 ± 13.72%) than PA (all p<0.05). Similarly, VB showed optimal diagnostic performance (AUC 0.994, sensitivity 96.00%, specificity 100.00%). No significant difference of VA, VB and VC was found between WT and MT. CONCLUSIONS: DR-CSI might be a promising and non-invasive way for characterizing parotid gland tumors.

Correlation between MRI (DWI and DCE) and cellularity of parotid gland pleomorphic adenomas.

PURPOSE: Parotid pleomorphic adenomas present a risk of recurrence, higher when the tumour is a hypocellular subtype. The aim of the study was to determine whether it is possible to characterize this histological subtype with diffusion and perfusion sequences of the preoperative MRI. METHODS: This retrospective study included 97 patients operated between 2010 and 2020. Histologic slides review was performed to classify tumours into three histologic subtypes: hypocellular, classical and hypercellular. Univariate and multivariate analyses studied the correlation between histology and diffusion and perfusion MRI parameters obtained with OleaSphere® software. RESULTS: The hypocellular subtype had higher apparent diffusion coefficient values than the other two subtypes: 2.13 ± 0.23, 1.83 ± 0.42, and 1.61 ± 0.4 × 10-3 mm2/s for hypocellular, classical and hypercellular subtype respectively (p < 0.0001). Multivariate analysis showed that an ADCmean > 1.88 × 10-3 mm2/s was suggestive of a hypocellular pleomorphic adenoma in 79% of the cases, with a specificity and PPV of 94 and 96% (p < 0.001), respectively. CONCLUSION: The histological subtype of a pleomorphic adenoma can be predicted preoperatively with ADC values. A prospective and multicentric study on a larger cohort is needed to confirm our results.

Mucosa-associated lymphoid tissue lymphoma at the parotid gland.

MALT (mucosa-associated lymphoid tissue) lymphomas are low-grade extra-nodal B-cell lymphomas that may involve various sites in the head and neck including the thyroid, salivary, and lacrimal glands. Development of MALT lymphoma in the head and neck is often associated with auto-immune diseases such as Sjögren syndrome or Hashimoto thyroiditis. Here, we report a case of a MALT lymphoma of the left buucal mucosa that likely arose in the parotid gland. The patient was successfully treated with surgical excision with chemotherapy and remained disease-free at the 10-year follow-up. Since it was rare in the head and neck region, we present this case.

Diagnostic Challenges and Imaging Considerations for Intraparotid Facial Nerve Schwannoma: A Case Report and Literature Review.

BACKGROUND A mass in the parotid gland usually indicates parotid gland neoplasia. Warthin tumors or pleomorphic adenomas are common differential diagnoses. Less frequently, other differential diagnoses and sites of origin are considered. Schwannomas are rare, benign tumors in the head and neck region. Even more rarely, these tumors occur in the intraparotid course of the facial nerve. In the following, we report about 2 patients in whom a mass in the right parotid gland was found incidentally during magnetic resonance imaging (MRI). CASE REPORT We reviewed data from the literature on intraparotid facial nerve schwannomas (IPFNS) and compared them with those from our cases. The focus was on data such as clinical history, clinical symptoms, electroneurography, and various imaging modalities, such as ultrasonography and MRI combined with diffusion-weighted imaging. CONCLUSIONS It is challenging to distinguish facial nerve schwannomas from other neoplasms. Patient's history, clinical symptoms, MRI examination with diffusion-weighted imaging, and high-resolution ultrasound imaging are decisive factors for diagnosis and should be performed when IPFNS is suspected. Diagnosis and therapy for IPFNS remain challenging. A wait-and-scan approach could be an option for patients with small tumors and good facial nerve function. On the other hand, patients with advanced tumors associated with limited facial nerve function can benefit from surgical approaches or stereotactic radiosurgery.

Case of clear-cell oncocytoma of parotid gland and literature review.

Oncocytoma is a benign tumor of the salivary gland. Its incidence is very low and very seldom documen-ted in literature. Clear-cell dominant oncocytoma is even less common. The tumor's clinical symptoms and imaging results are nonspecific, so distinguishing other salivary gland tumors (such as oncocytic carcinoma) from clear-cell renal carcinoma is difficult, possibly leading to misdiagnosis and maltreatment. Here, a case of clear-cell dominant oncocytoma was presented, and the relevant literature was evaluated to investigate the diagnosis and management of clear-cell dominant oncocytoma.

Carcinoma showing thymus-like elements (CASTLE) with amyloid deposition in the parotid gland.

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that commonly occurs in the thyroid gland. Extrathyroidal CASTLE is rarer, and only 11 cases of CASTLE of major salivary glands have been reported to date. We report the first case of amyloid deposition in parotid CASTLE. A 63-year-old man presented with a slowly growing mass in the left parotid region. Computed tomography revealed an approximately 28 × 23 mm mass lesion in the left parotid gland, and squamous cell carcinoma was suspected on biopsy. The patient underwent a parotidectomy with neck dissection. Morphologically, the tumor cells were squamoid and formed nests with lymphoid infiltration. Immunohistochemically, the tumor cells exhibited immunoreactivity for CD5, CD117/c-kit and Bcl-2, p40, and CK5 but not for p16. We diagnosed the tumor as parotid CASTLE. Amyloid deposition was also observed in the primary tumor and metastatic lymph node lesions, which were immunoreactive for cytokeratin 5. Tumor cytokeratin-derived amyloid deposition may be one of characteristics of parotid CASTLE.

Persistent bleeding following biopsy of an epidermoid cyst within the parotid gland.

Epidermoid cysts are benign lesions most commonly found in the skin but which can arise in many other locations including, very rarely the salivary glands. This rarity often leaves them off standard differential lists and can create a diagnostic dilemma. A patient with an incidentally detected parotid mass on MRI underwent core biopsy, which was unfortunately complicated by formation of a pseudoaneurysm and persistent arterial bleeding requiring coil embolisation. The histology showed only keratinous material and, in retrospect, the signal characteristics of the mass were entirely typical of an epidermoid cyst. Recognition of this common, benign entity in a very rare location can obviate the need for invasive tests and potential complications and direct management to more appropriate imaging follow-up.

Differential expression of TRKB tyrosine kinase in the two histological types of parotid salivary duct carcinoma with cancer aggressiveness.

Parotid salivary duct carcinoma (SDC) is a rare and aggressive parotid gland carcinoma (PGC). SDC has two origins: de novo and ex pleomorphic adenoma (SDC ex PA); however, because of its rarity, the clinical and molecular features of the two types of SDC are not sufficiently understood. Here, we studied the differences in their clinicopathological and molecular features using clinical specimens while comparing them to those of adenoid cystic carcinoma (AdCC), an intermediate-grade PGC. Clinicopathological analysis of tissues from patients with PGC revealed significant associations between histological types and malignant phenotypes, including nodal metastasis, recurrence, vascular invasion, and neural invasion, and revealed more malignant phenotypes of de novo SDC than of SDC ex PA. The de novo SDC showed a significantly higher frequency of intra-neural invasion (intra-NI) and vascular invasion than AdCC and SDC ex PA. PGCs with high intra-NI were significantly correlated with malignant phenotypes and survival rates. Recently, we observed the overexpression of tropomyosin receptor kinase B (TRKB), a receptor tyrosine kinase, in PGC cells. Here, immunohistochemical and clinicopathological analyses showed that TRKB was highly expressed in SDC cells, particularly de novo SDC cells, and was significantly associated with poor survival and highly malignant phenotypes, including intra-NI and vascular invasion. Collectively, these data show that TRKB expression is significantly elevated in PGC, particularly in de novo SDC, and can be one of the biomarkers of their aggressiveness.

Incidental [18F]FDG-avid focuses in parotid glands on PET/CT.

BACKGROUND: The number of unexpected focal [18F]FDG-avid findings (incidentalomas) within the parotid gland (PGI) continues to increase with the expanding use of PET/CT scanning. The prevalence of malignancy in PGIs is uncertain and appropriate management is unsettled. AIMS: We aimed to explore the underlying pathologies associated with PGI. MATERIALS AND METHODS: A retrospective review of all patients with parotid gland incidentaloma(s) treated at the Ear-Nose-Throat Department, Aarhus University Hospital, Denmark in the period 2012-2021, was performed. RESULTS: In total, 94 patients with one (n = 86) or two (n = 8) PGI(s) were included. In patients with one PGI, 72 (84%) focuses were benign, two (2%) focuses were malignant (both malignant melanoma metastases), and 12 (14%) focuses were undiagnosed. In patients with two PGIs, all 12 lesions with pathological examinations were benign (4 PGIs were undiagnosed). The median SUVmax found in benign lesions was higher (12.0) compared to malignant lesions (5.5) (p = .043). CONCLUSIONS AND SIGNIFICANCE: The prevalence of malignancy was low (2/94, 2.4%) in PGIs. Based on our findings, PGI in patients without a history of parotid malignancy, who undergo PET/CT scanning for reasons other than head and neck cancer (including malignant melanoma), may be managed similarly to patients with asymptomatic parotid gland tumors.

Disease and toxicity outcomes for a modern cohort of patients with squamous cell carcinoma of cutaneous origin involving the parotid gland: Comparison of volumetric modulated arc therapy and pencil beam scanning proton therapy.

OBJECTIVES: We sought to describe outcomes for locally advanced cutaneous squamous cell carcinoma (SCC) involving the parotid treated with volumetric modulated arc therapy (VMAT) versus pencil beam scanning proton beam therapy (PBT). MATERIALS AND METHODS: Patients were gathered from 2016 to 2022 from 5 sites of a large academic RT department; included patients were treated with RT and had parotid involvement by: direct extension of a cutaneous primary, parotid regional spread from a previously or contemporaneously resected but geographically separate cutaneous primary, or else primary parotid SCC (with a cutaneous primary ostensibly occult). Acute toxicities were provider-reported (CTCAE v5.0) and graded at each on treatment visit. Statistical analyses were conducted. RESULTS: Median follow-up was 12.9 months (1.3 - 72.8); 67 patients were included. Positive margins/extranodal extension were present in 34 cases; gross disease in 17. RT types: 39 (58.2 %) VMAT and 28 (41.8 %) PBT. Concurrent systemic therapy was delivered in 10 (14.9 %) patients. There were 17 treatment failures (25.4 %), median time of 168 days. Pathologically positive neck nodes were associated with locoregional recurrence (p = 0.015). Oral cavity, pharyngeal constrictor, and contralateral parotid doses were all significantly lower for PBT. Median weight change was -3.8 kg (-14.1 - 5.1) for VMAT and -3 kg (-16.8 - 3) for PBT (p = 0.013). Lower rates of ≥ grade 1 xerostomia (p = 0.002) and ≥ grade 1 dysguesia (p < 0.001) were demonstrated with PBT. CONCLUSIONS: Cutaneous SCC involving the parotid can be an aggressive clinical entity despite modern multimodal therapy. PBT offers significantly lower dose to organs at risk compared to VMAT, which seemingly yields diminished acute toxicities.