Clinicopathological features of incidental parotid lesions

Parotidectomy for deep lobe pleomorphic adenomas is associated with higher rates of complications and recurrence

BACKGROUND

Pleomorphic adenoma (PA) is a common parotid tumor, yet due to the relative rarity of deep lobe PA (DLPA), there is a paucity of information about its clinical presentation and surgical outcomes.

METHODS

We reviewed the charts of patients with previously untreated parotid PA between the years 1990 and 2015. Clinical parameters and surgical outcomes were compared between superficial lobe PA (SLPA) and DLPA.

RESULTS

The cohort comprised 147 cases of DLPA and 222 cases of SLPA. DLPA were larger (median 2.6 cm vs. 2.0 cm, p < 0.001), more often discovered incidentally on imaging (33%, n = 48) and had unique presentations (pharyngeal mass, dysphagia, otalgia). Postsurgical complications were more frequently observed in DLPA (41% vs. 30% in SLPA, p = 0.025), mainly transient facial nerve weakness. DLPA also showed higher recurrence rates (n = 6, 4.1% vs. n = 1, 0.4%, p = 0.016).

CONCLUSIONS

Parotidectomy for DLPA carries a higher risk of complications and recurrence compared to SLPA.

An ultrasound-based ensemble machine learning model for the preoperative classification of pleomorphic adenoma and Warthin tumor in the parotid gland

OBJECTIVES

The preoperative classification of pleomorphic adenomas (PMA) and Warthin tumors (WT) in the parotid gland plays an essential role in determining therapeutic strategies. This study aims to develop and validate an ultrasound-based ensemble machine learning (USEML) model, employing nonradiative and noninvasive features to differentiate PMA from WT.

METHODS

A total of 203 patients with histologically confirmed PMA or WT who underwent parotidectomy from two centers were enrolled. Clinical factors, ultrasound (US) features, and radiomic features were extracted to develop three types of machine learning model: clinical models, US models, and USEML models. The diagnostic performance of the USEML model, as well as that of physicians based on experience, was evaluated and validated using receiver operating characteristic (ROC) curves in internal and external validation cohorts. DeLong's test was used for comparisons of AUCs. SHAP values were also utilized to explain the classification model.

RESULTS

The USEML model achieved the highest AUC of 0.891 (95% CI, 0.774-0.961), surpassing the AUCs of both the US (0.847; 95% CI, 0.720-0.932) and clinical (0.814; 95% CI, 0.682-0.908) models. The USEML model also outperformed physicians in both internal and external validation datasets (both p < 0.05). The sensitivity, specificity, negative predictive value, and positive predictive value of the USEML model and physician experience were 89.3%/75.0%, 87.5%/54.2%, 87.5%/65.6%, and 89.3%/65.0%, respectively.

CONCLUSIONS

The USEML model, incorporating clinical factors, ultrasound factors, and radiomic features, demonstrated efficient performance in distinguishing PMA from WT in the parotid gland.

CLINICAL RELEVANCE STATEMENT

This study developed a machine learning model for preoperative diagnosis of pleomorphic adenoma and Warthin tumor in the parotid gland based on clinical, ultrasound, and radiomic features. Furthermore, it outperformed physicians in an external validation dataset, indicating its potential for clinical application.

KEY POINTS

• Differentiating pleomorphic adenoma (PMA) and Warthin tumor (WT) affects management decisions and is currently done by invasive biopsy. • Integration of US-radiomic, clinical, and ultrasound findings in a machine learning model results in improved diagnostic accuracy. • The ultrasound-based ensemble machine learning (USEML) model consistently outperforms physicians, suggesting its potential applicability in clinical settings.

Risk of Carcinoma in Pleomorphic Adenomas of the Parotid

Importance

Surgery is the mainstay of treatment for pleomorphic adenomas (PAs) of the parotid to prevent further growth and potential future malignant transformation. While historical case series have reported transformation rates as high as 10%, there is a lack of contemporary methodologically sound data.

Objective

To examine the rate of carcinoma ex pleomorphic adenoma (CXPA) detection in untreated PAs and investigate factors associated with malignant neoplasm.

Design, Setting, and Participants

This cohort study reviewed all cases of primary PAs managed at a quaternary referral center between December 1990 and January 2015. Patients whose clinical presentation was compatible with a primary benign PA and whose history indicated tumor duration of over 1 year were included. Data were analyzed from January to April 2023.

Exposure

Untreated PA.

Main Outcomes and Measures

Rate of CXPA detection among untreated PAs and association of tumor duration with rates of CXPA detection. Pathology slides of patients who underwent surgery were reviewed by a single expert pathologist for the presence of CXPA. Univariable logistic regression was performed to evaluate possible factors associated with CXPA.

Results

A total of 260 patients (median age, 47 years [IQR, 38-60 years]; 174 [66.9%] female) had a median tumor duration of 3.2 years (range, 1-30 years; mean [SD], 5.7 [5.5] years). Patients were divided into 4 groups by tumor duration: 1 to 4 years (158 [60.7%]), 5 to 9 years (47 [18.1%]), 10 to 14 years (27 [10.4%]), and 15 to 30 years (28 [10.8%]). In 156 of 170 patients who underwent preoperative fine-needle aspiration (91.8%), a benign tumor was diagnosed; 5 of these patients (3.2%; 95% CI, 1.4%-7.3%) were later diagnosed with CXPA on pathology after eventual excision, and the rate of high grade CXPA was 1.3%. None of the patients had permanent facial nerve paralysis. Tumor size at presentation (odds ratio [OR], 1.66; 95% CI, 1.22-2.24) and incremental (per year) increase in age (OR, 1.04; 95% CI, 1.01-1.08) were found to be associated with CXPA, whereas tumor duration was not (OR, 1.00; 95% CI, 1.00-1.01).

Conclusions and Relevance

In this study, the rate of malignant neoplasm detection among initially untreated PA was 3.2%. The results suggest that tumor size and older age are associated with the development of CXPA, while tumor duration is not. Observation of PA for longer periods was not associated with serious permanent complications.

Preoperative Diagnosis of Warthin Tumors Combining Cytological, Clinical and Ultrasonographic Information within a Multidisciplinary Approach in a Lump Clinic

(1) Background: Warthin tumors account for about 20% of all benign salivary tumors, approaching 50% if we consider only the parotid gland. Wait and see is considered a reasonable option, but the diagnosis should be certain. Diagnosis can be based on morphological and cytological data, but the sensitivity of the fine needle aspiration cytology (FNAC) is not absolute, with a high rate of non-diagnostic findings in the event of a Warthin tumor, hindering the counseling and therapeutic decisions. The aim of the study is to evaluate the reliability of FNAC and its combination with anamnestic, clinical, and ultrasonographic data in diagnosing Warthin tumors. (2) Methods: A total of 413 patients affected by masses within the major salivary gland and managed between 2017 and 2022 at our institution have been included in the present retrospective study. Each patient underwent fine needle aspiration biopsy (FNAB) with a subsequent cytological diagnosis; successively, for each patient, the clinician (otolaryngologist) and the histopathologist discussed the combination of cytological (even non-diagnostic), clinical, and ultrasonographic data in order to make a "multiparametric" diagnosis. A total of 214 cases were subsequently submitted to surgical resection and had a final histopathology report, to which the cytological and the multiparametric diagnoses can be compared. We extracted all the patients with a cytological, multiparametric, and/or histological diagnosis of Warthin tumors in order to assess the sensitivity and specificity of FNAC and of multiparametric analysis in diagnosing Warthin tumors in case of a major salivary gland mass. (3) Results: One hundred thirty-two cases had a cytological, multiparametric, and/or histological diagnosis of Warthin tumors. FNAC displays a sensitivity of 68.4% and a specificity of 98.7% in diagnosing Warthin tumors. The multiparametric evaluation allowed a considerable improvement in sensitivity (92.9% vs. 68.4%), minimizing the number of non-diagnostic results and preserving at the same time a similar value of specificity (95.5% vs. 98.7%). Notably, none of the patients with a cytological or multiparametric diagnosis of Warthin were affected by a malignant lesion in the final histopathological report. (4) Conclusions: In the case of Warthin tumors, a multiparametric evaluation encompassing anamnestic, clinical, and cytological data is effective in reducing the number of non-diagnostic reports and can safely guide the management of a tumor (e.g., antibiotic treatment of infectious complications, assign a low priority to surgery, even consider observation avoiding surgery) which is absolutely benign and can be associated with no clinically relevant issues.

Incidentalomas in the head & neck

Incidental findings (IFs) in the head & neck are a frequent challenge to the reporting radiologist. A combination of complex anatomy, widely varied imaging techniques and the high prevalence of benign pathology, makes safe and appropriate management of head & neck IFs problematic. The non-head & neck radiologist is unlikely to have prior personal experience of the relevant specialties or current involvement with the pertinent multidisciplinary teams, creating unfamiliarity with both the clinical aspects of head & neck disease and the value of examination techniques. This triumvirate of complex anatomy, pathology and imaging creates the perfect environment for excessive investigation and overdiagnosis. In this article, the most frequently encountered and clinically relevant head & neck IFs are summarised. To reflect daily clinical practice, we will firstly consider anatomic abnormalities identified on cross-sectional imaging and ultrasound, followed by a review of PET-CT incidental findings.

Parotid gland incidentalomas: A single-institution experience

PURPOSE

Parotid gland incidentaloma (PGI) management has not been well characterized in the literature. This study assesses clinicopathologic features, initial evaluation, management, and outcomes of PGIs discovered on various imaging modalities.

MATERIALS AND METHODS

This is a retrospective case series from a single academic institution. The study cohort included 34 patients with parotid gland incidentalomas discovered between January 2009 and December 2019.

RESULTS

Parotid gland incidentalomas were most frequently identified on magnetic resonance imaging (16 patients, 47.1%). Most patients (26 patients, 76.5%) underwent further evaluation with subsequent imaging, most often magnetic resonance imaging (18 patients, 69.2%), and fine needle aspiration biopsy (33 patients, 97.1%). Most tumors were benign on fine needle aspiration biopsy (19 patients, 57.6%). Most cases (21 patients, 61.8%) were managed with observation without parotidectomy. Malignant findings on fine needle aspiration cytology were associated with increased likelihood of undergoing parotidectomy (25% vs 0%; p = 0.04). Among the patients who received a parotidectomy, most (8 patients, 61.5%) had benign findings on final histopathology.

CONCLUSION

Parotid gland incidentalomas were discovered across a diverse set of imaging modalities in our institution. Magnetic resonance imaging and fine needle aspiration were often performed for further evaluation. Most cases were found to be benign on fine needle aspiration and were managed with observation. These findings highlight the necessity of appropriate work-up for these tumors, and the need for shared decision making between the patient and the physician in selecting the appropriate treatment strategy.

Prevalence and Clinical Implications of Incidentally Detected Parotid Lesions as Blind Spot on Brain MRI: A Single-Center Experience

Background and objective: This study was conducted to assess the prevalence and clinical implications of parotid lesions detected incidentally during brain magnetic resonance imaging (MRI) examination. Materials and Methods: Between February 2016 and February 2021, we identified 86 lesions in the brain MRI reports of 84 patients that contained the words “parotid gland” or “PG”. Of these, we finally included 49 lesions involving 45 patients following histopathological confirmation. Results: Based on the laboratory, radiological or histopathological findings, the prevalence of incidental parotid lesions was low (1.2%). Among the 45 study patients, 41 (91.1%) had unilateral lesions, and the majority of the lesions were located in the superficial lobe (40/49, 81.6%). The mean size of the parotid lesions was 1.3 cm ± 0.4 cm (range, 0.5 cm–2.8 cm). Of these, 46 parotid lesions (93.9%) were benign, whereas the remaining three lesions were malignant (6.1%). Conclusions: Despite the low prevalence and incidence of malignancy associated with incidental parotid lesions detected on brain MRI, the clinical implications are potentially significant. Therefore, clinical awareness and appropriate imaging work-up of these lesions are important for accurate diagnosis and timely management.