Ewing's sarcoma of the parotid gland: A rare entity with review of the literature.

Background: Ewing's sarcoma is a rare malignant entity. Extraosseous Ewing's sarcoma (EES) of the head and neck region is a rare occurrence, and Ewing's sarcoma of the parotid gland is even rarer. To the best of our knowledge, we reported the first case of extraskeletal ES originating from the parotid gland in the Tunisian literature. Case report: We report a rare case of EES of the parotid gland in a 35-year-old female. She presented with left parotid tumefaction. Physical examination revealed solid and fixed mass associated with facial paralysis. Magnetic resonance imaging illustrated a left intra-parotid process occupying the entire gland measuring 42 mm infiltrating the masseter and pterygoid muscles. The patient had a total left parotidectomy with ipsilateral triangular lymph node dissection. The definitive pathological examination and the immunohistochemical staining confirmed a primary peripheral neuroectodermal tumor or PNET with the presence of a specific EWING/PNET-type translocation in 60% of the tumor cells. She had an adjuvant chemotherapy (four cycles of vincristine, doxorubicin, cyclophosphamide alternating with ifosfamide and etoposide) followed by external radiotherapy. Conclusion: A clinical and radiological follow-up by cervical MRI was done every 3 months and The 10-month follow-up showed no locoregional and distant recurrence.

Introduction: Le sarcome d'Ewing est une entité maligne rare. La localisation extra osseuse en particulier la région de la tête et du cou est caractérisée par son agressivité locorégionale. Nous rapportons le cas d'un sarcome d'Ewing de la parotide. A notre connaissance, il s'agit du premier cas rapporté dans la littérature tunisienne. Presentation du cas: Il s'agit d'une femme âgée de 35 ans qui a consulté initialement pour une tuméfaction au niveau de la glande parotide gauche. L'examen clinique a révélé une masse sous angulomandibulaire associée à une paralysie faciale périphérique gauche. Une IRM parotidienne a objectivé un processus intra-parotidien gauche occupant l'entièreté de la glande mesurant 42 mm mal limitée infiltrant modérément le muscle masséter et ptérygoïdiens. Le bilan d'extension était sans anomalie. La patiente a eu une parotidectomie gauche large avec un curage triangulaire homolatéral. L'examen anatomopathologique définitif et l'étude par hybridation in situ en fluorescence (FISH) ont confirmé la présence d'une translocation spécifique type EWING/PNET dans 60% des cellules tumorales. La patiente a été traitée par une chimiothérapie type VDC/IE (vincristine, doxorubicine, cyclophosphamide en alternance avec ifosfamide, et etoposide) suivie d'une radiothérapie externe. Un suivi clinique et radiologique trimestrielle n'a montré aucune récidive locorégionale ni à distance à ce jour soit à 10 mois de recul. Conclusion: Une surveillance clinique et radiologique trimestrielle a été faite et le contrôle à 10 mois n'a pas montré de récidive locorégionale ou à distance.

Extra-oral, Non-mucosal Approach for Oncologic Resections of the Mandible: A Case Series.

Introduction: Malignant tumors afflicting the sub-condylar area and ascending ramus of the mandible without mucosal involvement are extremely rare. Traditional approaches such as lip-split-cheek flap and Visor flap would prove sub-optimal and excessive for such limited lesions and entail salivary contamination and mental nerve sacrifice. To circumvent these limitations, we developed a surgical approach that achieves wide, extra-oral exposure to the condyle and ascending ramus and permits controlled resection, affording protection to the facial nerve branches and mental nerve, while avoiding salivary contamination. Case Report: The main features of the approach include a pre-auricular skin crease incision extendable both ways, trans-parotid dissection with protection of facial nerve branches, and controlled bony resection. In all cases, monobloc resection was possible with preservation of the uninvolved facial nerve branches, avoidance of salivary contamination, and prompt healing. Conclusion: An extra-oral non-mucosal surgical approach is described for highly selected cases of mandibular resection.

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.

Bilateral Sialadenitis as an Uncommon Initial Manifestation of Infectious Mononucleosis: A Case Report.

Sialadenitis has rarely been reported in patients with infectious mononucleosis (IM). Our patient was a 22-year-old man who presented with bilateral swelling of the parotid and submandibular glands, a fever, malaise, and splenomegaly. Laboratory tests revealed an increased percentage of atypical lymphocytes in the leukocyte fraction. Serological testing for antibodies against Epstein-Barr virus (EBV) revealed an acute infection pattern. The patient was diagnosed with sialadenitis associated with IM caused by EBV infection. With symptomatic treatment, the salivary gland swelling completely resolved within a week. This case suggests that EBV-induced IM should be included in the differential diagnosis of diffuse sialadenitis with elevated atypical lymphocyte counts.

Factors influencing Frey syndrome after parotidectomy with acellular dermal matrix.

BACKGROUND: Frey syndrome, also known as ototemporal nerve syndrome or gustatory sweating syndrome, is one of the most common complications of parotid gland surgery. This condition is characterized by abnormal sensations in the facial skin accompanied by episodes of flushing and sweating triggered by cognitive processes, visual stimuli, or eating. AIM: To investigate the preventive effect of acellular dermal matrix (ADM) on Frey syndrome after parotid tumor resection and analyzed the effects of Frey syndrome across various surgical methods and other factors involved in parotid tumor resection. METHODS: Retrospective data from 82 patients were analyzed to assess the correlation between sex, age, resection sample size, operation time, operation mode, ADM usage, and occurrence of postoperative Frey syndrome. RESULTS: Among the 82 patients, the incidence of Frey syndrome was 56.1%. There were no significant differences in sex, age, or operation time between the two groups (P > 0.05). However, there was a significant difference between ADM implantation and occurrence of Frey syndrome (P < 0.05). ADM application could reduce the variation in the incidence of Frey syndrome across different operation modes. CONCLUSION: ADM can effectively prevent Frey syndrome and delay its onset.

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.

Mucoepidermoid microcarcinoma in the context of parotid gland cyst.

Mucoepidermoid carcinoma is a type of salivary gland cancer that can develop in the context of a parotid gland cyst. This type of tumor is composed of mucous, epidermoid, and intercalated cells, and usually presents as a slow-growing and painless mass. A parotid gland cyst is a condition in which a fluid-filled sac forms in the parotid gland. The tumor can be masked as it develops within the parotid cyst. A 45-year-old female patient presented with a suspect of benign neoplasm of the major salivary gland. She underwent partial right parotidectomy, which upon pathological analysis confirmed the diagnosis of mucoepidermoid microcarcinoma associated with parotid gland cysts. The patient did well and continues under regular follow-up with no further treatment.

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.

Case-tailored indicated extracapsular dissection versus "one-size-fits-all" nerve dissection: Has the bet been won?

OBJECTIVE: The aim of the study was to trace the development of surgical therapy in a large cohort, examine its changes at one single institution that has been specializing in salivary gland pathologies over the last 22 years, and to determine the extent to which a possible shift in the surgical therapy of parotid benign tumors towards less radical methods was correlated with a change in the incidence of facial palsy and Frey's syndrome. STUDY DESIGN: Retrospective clinical study. METHODS: A retrospective evaluation of the records of all patients treated for benign parotid tumors at a tertiary referral center between 2000 and 2022 was carried out. Surgical methods were classified into four groups: extracapsular dissection, partial superficial parotidectomy, superficial parotidectomy and complete parotidectomy. RESULTS: A total of 4037 patients were included in the study. Our analysis demonstrated an increase in the total number of parotidectomies for benign lesions from 71 (2000) to 298 (2022), mostly due to the increase in extracapsular dissections (from 9 to 212). The increased performance of less radical surgery was associated with a significantly decreased incidence of perioperative complications. CONCLUSIONS: Our study showed that the increased performance of less radical surgery was associated with better functional outcomes over the years.

Radiation-induced xerostomia is related to stem cell dose-dependent reduction of saliva production.

BACKGROUND AND PURPOSE: Previous studies have shown that the mean dose to the parotid gland stem cell rich regions (Dmean,SCR) is the strongest dosimetric predictor for the risk of patient-reported daytime xerostomia. This study aimed to test whether the relationship between patient-reported xerostomia and Dmean,SCR is explained by a dose-dependent reduction of saliva production. MATERIAL/METHODS: In 570 head and neck cancer patients treated with definitive radiation therapy (RT), flow from the parotid (FLOWPAR) and submandibular/sublingual glands (FLOWSMSL) and patient-reported daytime (XERDAY) and nighttime xerostomia (XERNIGHT) were prospectively measured before, and at 6 and 12 months after RT. Using linear mixed effect models, the relations of mean dose to the parotid glands (Dmean,par), Dmean,SCR, non-SCR parotid gland tissue (Dmean,non-SCR), submandibular glands (Dmean,sub) and oral cavity (Dmean,oral) with salivary flow and xerostomia were analyzed while correcting for known confounders. RESULTS: Dmean,SCR proved to be responsible for the effect of Dmean,par on FLOWPAR (p≤0.03), while Dmean,non-SCR did not affect FLOWPAR (p≥0.11). To illustrate, increasing Dmean,SCR by 10 Gy at fixed Dmean,non-SCR, reduced FLOWPAR by 0.02 (25%) after RT. However, if the opposite happened, no change in FLOWPAR was observed (0.00 ml/min [4%]). As expected, Dmean,sub was significantly associated with FLOWSMSL (p<0.001). For example, increasing Dmean,sub by 10 Gy, reduced FLOWSMSL with 0.07 ml/min (26%) after RT. Xerostomia scores were also affected by dose to the salivary glands. Dmean,SCR and Dmean,oral were associated with higher XERDAY scores (p≤0.05), while Dmean,sub increased XERNIGHT scores (p=0.01). For example, an increase of 10 Gy in Dmean,SCR raised XERDAY scores with 2.13 (5%) points after RT, while an additional 10 Gy in Dmean,subs increased XERNIGHT scores with 2.20 points (6%) after RT. Salivary flow was not only associated with radiation dose, but also with xerostomia scores in line with the salivary glands' functions, i.e., FLOWPAR only influenced XERDAY (p<0.001, 10.92 points lower XERDAY per 1 ml/min saliva), while FLOWSMSL affected XERDAY and XERNIGHT (p≤0.004, 6.69 and 5.74 points lower XERDAY and XERNIGHT, respectively, per 1 ml/min saliva). Therefore, the observed relations between dose and xerostomia were corrected for salivary flow. As hypothesized, Dmean,SCR only increased XERDAY scores via reducing FLOWPAR; whereas the effects of Dmean,oral on XERDAY and of Dmean,sub on XERNIGHT were independent of salivary flow. CONCLUSION: Higher SCR region dose reduced parotid gland saliva production, subsequently resulting in higher daytime xerostomia scores. Consequently, this study supports the clinical implementation of stem cell sparing RT to preserve salivary flow with the aim of reducing the risk of xerostomia.

Treatment of Warthin's Tumors of the Parotid Gland With Radiofrequency Ablation: A Systematic Review of the Current Literature.

Objective: Warthin's tumors of the parotid gland can be safely observed. Definitive treatment usually requires parotidectomy under general anesthesia. The decision to operate on Warthin's tumors of the parotid gland can be complicated in patients who wish to avoid risks of surgery and general anesthesia. This systematic review explores the potential of radiofrequency ablation (RFA) as a minimally invasive alternative. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model was used to collect 3 relevant studies that focused on RFA treatment for Warthin's tumors. The cumulative averages for tumor size and cosmetic scores were then quantified for patients with Warthin's tumors who underwent RFA therapy. The PRISMA systematic review method was employed to the PubMed and EMBASE databases. The comprehensive search term "Warthin Tumor Treatment" yielded 1299 articles from the years 1955 to 2023, 3 of which met inclusion criteria and were then selected. Results: The 3 quantitative studies collectively assessed 37 patients with Warthin's tumors treated with RFA. Patients experienced an average tumor size reduction of 85.03% at 12 months post-RFA. There were minimal complications associated with RFA in these patients. Conclusion: This study suggests that RFA is an alternative to parotidectomy for the symptomatic treatment of Warthin's tumors. RFA procedures demonstrated substantial tumor size reduction with few complications. However, further meta-analysis and comparison with alternative treatments is warranted to establish RFA's role in treatment of Warthin's tumors. The study is limited by its reliance on only 2 databases and a lack of comprehensive examination of different RFA settings.

Oncologic outcomes of the most prevalent major salivary gland cancers: retrospective cohort study from single center.

BACKGROUND: The preoperative diagnosis of salivary gland cancer (SGC) is crucial for the application of appropriate treatment, particularly involving the extension of the resection. METHODS: Retrospective search of medical database identified 116 patients treated surgically with malignant tumors of salivary gland between 2010 and 2020. Analysis included the demographical data, clinical course, type of surgical and adjuvant treatment, histology type and margin status, perivascular invasion (LVI), perineural invasion (PNI), metastatic lymph nodes (LN). Facial nerve function, recurrence-free and overall survival were evaluated. Adequate statistics were used for data analysis. RESULTS: The final cohort included 63 SGC patients, with adenoid cystic carcinoma the most common pathological type (27%, n = 17), followed by adenocarcinoma (17.4% n = 11). T1 and T2 patients accounted for majority cases (n = 46). The lymph node metastases were confirmed with the histopathology in 31.7% (n = 20). Distant metastases were observed in 4.8% of cases (n = 3). 38% (n = 24) of SGC were treated selectively with surgery, 49.2% (n = 31) had postoperative radiotherapy and 15.9% (n = 10)-radio-chemotherapy. The final facial nerve function was impaired in 38% of patients. Mean overall survival (OS) for all patients was 108.7 (± 132.1) months, and was the most favorable for acinar cell carcinoma (118.9 ± 45.4) and the poorest for squamous cell carcinoma (44 ± 32). Cox regression analysis of disease-free survival and OS identified significant association only with patients' age over 65 years, the hazard ratio of 7.955 and 6.486, respectively. CONCLUSIONS: The efficacy of treatment modalities for SGC should be verified with regard to the histopathological type, but also the patients' age should be taken into account.

Parotid Mucoepidermoid Carcinoma in a Pediatric Patient: A Case Report.

Mucoepidermoid carcinomas (MECas) are malignant epithelial salivary gland neoplasms composed of a variable mixture of epidermoid and mucus-secreting cells arising from the ductal epithelium. Of all salivary gland tumors, MECas are the most common malignant lesions of the parotid gland. This case report aims to present a 14-year-old female patient with a history of progressive enlargement of a 3 cm in diameter, painless, mobile mass located at the parotid gland without facial nerve dysfunction. The lesion was exhaustively studied preoperatively, and studies were carried out. Contrast-enhanced computerized tomography (CECT) showed an increase in nodule numbers and size at the level of both the jugular and posterior cervical chains. In contrast, the gland's fine needle aspiration (FNA) showed a mucinous background. The histologic depiction established that the tumor was MECa of the parotid gland. The literature reviews on MECa encompass discussions about its prevalence, etiology, histological findings, and treatment.

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.

Evaluation of submandibular and parotid salivary glands by ultrasonography in patients with diabetes.

BACKGROUND: Microvascular complications of diabetes mellitus (DM) include oral manifestations and complications, including xerostomia, reduced salivary flow, susceptibility to infection, periodontal disease and salivary gland enlargement. OBJECTIVE: The present study aims to evaluate B-mode ultrasonography (USG) parameters such as size, volume and echogenicity of the submandibular and parotid salivary glands on both sides, shear-wave elastography (SWE) value and colour Doppler properties in patients with DM and healthy control groups. METHODS: In total, 160 right and left submandibular glands and 160 right and left parotid glands of 80 patients, 40 patients (20 type 1 DM, 20 type 2 DM) and 40 healthy control group, between the ages of 18-70 were examined by USG. Echogenicity, parenchyma internal structure, margin and dimensional measurements (antero-posterior length, supero-inferior length, medio-lateral length and volume) and colour Doppler with 'ML 6-15-D Matrix Array (4-15 MHz)' probe, shear-wave elastography '9L-D (2-8 MHz)' probe was investigated. RESULT: Statistically significant difference was observed in echogenicity in the right submandibular gland, echogenicity in the right parotid gland, margin characteristics, parenchymal homogeneity and colour Doppler characteristics between the type 1 DM, type 2 DM and control groups (p < .05). It was observed that the size, volume and SWE values of both submandibular and parotid glands were higher in the DM patient group than in the control group. Higher values were observed in type 2 DM compared to type 1 DM in the patient group. CONCLUSION: USG is an effective imaging technique in investigating the effects of diabetes on the submandibular and parotid salivary glands.

Incidence of Facial Nerve Paralysis After Parotidectomy: Our Experience.

Facial nerve palsy (FNP) is a well-recognized complication following parotidectomy, with varying reported incidence rates in the literature. Understanding the incidence and factors contributing to FNP is crucial for optimizing patient care and surgical outcomes. A retrospective analysis was conducted on 78 patients who underwent parotidectomy at a tertiary care institution (Hospital de Especialidades Carlos Andrade Marin, Quito) over a 36-month period. Demographic data, preoperative pathology reports, surgical details, and postoperative outcomes, including FNP incidence and severity, were analyzed. The mean age of the cohort was 53 years, with a male-to-female ratio of 0.8:1. Fine needle aspiration revealed benign pathology in 70.5% of cases, with superficial parotidectomy being the most common surgical approach (84.6%). Postoperatively, FNP was observed in 51.2% of cases, with transient paralysis in 62.5% and persistent paralysis in 37.5%. The majority of FNP cases were classified as grade II and III according to the House-Brackmann grading system. A tumor size larger than 4 cm was associated with a higher incidence of FNP (57.5%). This study provides valuable insights into the incidence and severity of FNP following parotidectomy. Despite efforts to standardize surgical techniques, persistent paralysis remains a significant concern.

The anterior lobe of the parotid gland：A CT sialographic study.

OBJECTIVES: To investigate the imaging and anatomic features of the anterior lobe (AL) of the superficial parotid gland. METHODS: Computed tomographic sialography examinations were undertaken for 142 parotid glands in 77 patients. Whole computer tomography (CT) data were analyzed using multi-planar reformation and maximum intensity projection to generate sialographic CT images. The tributary ducts of the superficial parotid gland were analyzed to classify the parotid morphology. Three-dimensional analyses were used to investigate the AL and its relationship with adjacent anatomic landmarks. RESULTS: Four major types (I-IV) and two minor types (V-VI) of the AL and the superficial parotid gland were observed. Type I AL (83/142) was contiguous and not separated from the retromandibular parotid gland. Type II AL (16/142) was detached from the retromandibular parotid gland with one to four tributary ducts. Type III AL (12/142) showed a small isolated lobe above the Stensen's duct around the anterior edge of the masseter. Type IV (28/142) showed the absence of the AL. Type V (3/142) shows the absence of the retromandibular parotid gland. Type VI (3/142) showed the presence of ectopic salivary gland beneath the Stensen's duct anterior to the retromandibular parotid gland. CONCLUSIONS: The AL gives rise to the morphological variations of the superficial parotid gland. AL also gives rise to the accessory parotid gland when it is detached from the retromandibular parotid gland.

Interobserver delineation variability of computed tomography-based radiomic features of the parotid gland.

PURPOSE: To assess the interobserver delineation variability of radiomic features of the parotid gland from computed tomography (CT) images and evaluate the correlation of these features for head and neck cancer (HNC) radiotherapy patients. MATERIALS AND METHODS: Contrast-enhanced CT images of 20 HNC patients were utilized. The parotid glands were delineated by treating radiation oncologists (ROs), a selected RO and AccuContour auto-segmentation software. Dice similarity coefficients (DSCs) between each pair of observers were calculated. A total of 107 radiomic features were extracted, whose robustness to interobserver delineation was assessed using the intraclass correlation coefficient (ICC). Pearson correlation coefficients (r) were calculated to determine the relationship between the features. The influence of excluding unrobust features from normal tissue complication probability (NTCP) modeling was investigated for severe oral mucositis (grade ≥3). RESULTS: The average DSC was 0.84 (95% confidence interval, 0.83-0.86). Most of the shape features demonstrated robustness (ICC ≥0.75), while the first-order and texture features were influenced by delineation variability. Among the three observers investigated, 42 features were sufficiently robust, out of which 36 features exhibited weak correlation (|r|<0.8). No significant difference in the robustness level was found when comparing manual segmentation by a single RO or automated segmentation with the actual clinical contour data made by treating ROs. Excluding unrobust features from the NTCP model for severe oral mucositis did not deteriorate the model performance. CONCLUSION: Interobserver delineation variability had substantial impact on radiomic features of the parotid gland. Both manual and automated segmentation methods contributed similarly to this variation.

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.

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.