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. 2023 Nov 1;149(11):1034-1041.
doi: 10.1001/jamaoto.2023.3212.

Risk of Carcinoma in Pleomorphic Adenomas of the Parotid

Helena Levyn  1 , Tejas Subramanian  2 , Alana Eagan  1 , Nora Katabi  3 , Oscar Lin  3 , NatalieDeana Dizon Badillo  2 , German Martinez  3 , Daniel W Scholfield  1 , Richard J Wong  1 , Jatin P Shah  1 , Babak Givi  1 , Luc G T Morris  1 , Ian Ganly  1 , Snehal G Patel  1
Affiliations

Risk of Carcinoma in Pleomorphic Adenomas of the Parotid

Helena Levyn et al. JAMA Otolaryngol Head Neck Surg. .

Abstract

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.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Patel reported holding equity in Summit Biomedical LLC outside the submitted work and having patents for methods of cancer detection using PARPI-FL; an apparatus, system, and method for providing laser steering and focusing for incision, excision, and ablation of tissue in minimally invasive surgery; systems, methods, and apparatus for multichannel imaging of fluorescent sources in real time; cyclic peptides with enhanced nerve-binding selectivity, nanoparticles bound with said cyclic peptides, and use of same for real-time in vivo nerve tissue imaging; and imaging systems and methods for tissue differentiation, such as for intraoperative visualization. No other disclosures were reported.

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