Parotid Incidentaloma Identified by Positron Emission/Computed Tomography: When to Consider Diagnoses Other than Warthin Tumor

Abstract

Introduction Parotid gland incidentalomas (PGIs) are unexpected hypermetabolic foci in the parotid region that can be found when scanning with whole-body positron emission/computed tomography (PET/CT). These deposits are most commonly due to benign lesions such as Warthin tumor.

Objective The aim of this study was to determine the prevalence of PGIs identified in PET/CT scans and to assess the role of smoking in their etiology.

Methods We retrospectively reviewed all PET/CT scans performed at our center in search of PGIs and identified smoking status and standardized uptake value (SUVmax) in each case. We also analyzed the database of parotidectomies performed in our department in the previous 10 years and focused on the pathologic diagnosis and the presence or absence of smoking in each case.

Results Sixteen cases of PGIs were found in 4,250 PET/CT scans, accounting for 0.4%. The average SUVmax was 6.5 (range 2.8 to 16). Cytology was performed in five patients; it was benign in four cases and inconclusive in one case. Thirteen patients had a history of smoking. Of the parotidectomies performed in our center with a diagnosis of Warthin tumor, we identified a history of smoking in 93.8% of those patients.

Conclusions The prevalence of PGIs on PET/CT was similar to that reported by other authors. Warthin tumor is frequently diagnosed among PGIs on PET/CT, and it has a strong relationship with smoking. We suggest that a diagnosis other than Warthin tumor should be considered for PGIs in nonsmokers.

Keywords

parotid gland - adenolymphoma - PET scan - cigarette smoking

• References

• 1 Lee SK, Rho BH, Won KS. Parotid incidentaloma identified by combined 18F-fluorodeoxyglucose whole-body positron emission tomography and computed tomography: findings at grayscale and power Doppler ultrasonography and ultrasound-guided fine-needle aspiration biopsy or core-needle biopsy. Eur Radiol 2009; 19 (9) 2268-2274
• 2 Horiuchi M, Yasuda S, Shohtsu A, Ide M. Four cases of Warthin's tumor of the parotid gland detected with FDG PET. Ann Nucl Med 1998; 12 (1) 47-50
• 3 Klijanienko J, Petras S, De Bosschere L, Paulmier B, Le Tourneau C, Rodriguez J. False-positive FDG PET/CT uptake in Warthin tumor in head and neck oncological patients confirmed by a fine needle aspiration. Diagn Cytopathol 2012; 40 (3) 282-284
• 4 Enomoto A, Nakahara H, Uchihashi T, Tsuji H, Hamada S. Fluorodeoxyglucose-positive Warthin tumor in a neck node mimicking metastasis in primary intraosseous left posterior mandibular cancer staging with positron emission tomography/computed tomography. J Oral Maxillofac Surg 2011; 69 (7) 2052-2054
• 5 Iwai T, Baba J, Shibasaki M , et al. 18F-fluorodeoxyglucose-positive Warthin tumor in a contralateral cervical lymph node mimicking metastasis in tongue cancer staging with PET/CT. J Craniofac Surg 2012; 23 (5) e507-e509
• 6 Coronado Poggio M, Couto Caro RM, Rodado Marina S, Martín Curto LM. 18F-FDG PET/TAC Semiology. Rev Esp Med Nucl 2008; 27 (4) 284-304, quiz 305–306
• 7 Peter Klussmann J, Wittekindt C, Florian Preuss S, Al Attab A, Schroeder U, Guntinas-Lichius O. High risk for bilateral Warthin tumor in heavy smokers—review of 185 cases. Acta Otolaryngol 2006; 126 (11) 1213-1217
• 8 Pinkston JA, Cole P. Cigarette smoking and Warthin's tumor. Am J Epidemiol 1996; 144 (2) 183-187
• 9 Sadetzki S, Oberman B, Mandelzweig L , et al. Smoking and risk of parotid gland tumors: a nationwide case-control study. Cancer 2008; 112 (9) 1974-1982
• 10 Reddy VM, Thangarajah T, Castellanos-Arango F, Panarese A. Conservative management of Warthin tumour. J Otolaryngol Head Neck Surg 2008; 37 (5) 744-749
• 11 Wang HC, Zuo CT, Hua FC , et al. Efficacy of conventional whole-body 18 F-FDG PET/CT in the incidental findings of parotid masses. Ann Nucl Med 2010; 24 (8) 571-577
• 12 Zbären P, Schär C, Hotz MA, Loosli H. Value of fine-needle aspiration cytology of parotid gland masses. Laryngoscope 2001; 111 (11 Pt 1) 1989-1992
• 13 Chedid HM, Rapoport A, Aikawa KF, Menezes AdosS, Curioni OA. Warthin's tumor of the parotid gland: study of 70 cases. Rev Col Bras Cir 2011; 38 (2) 90-94