Clinical Review & Education

Clinical Challenge | RADIOLOGY

A Pediatric Soft Palate Mass Amy L. Hughes, MD; Edward Yang, MD; Sara O. Vargas, MD

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Figure. Pediatric soft palate mass. A, Sagittal T2-weighted magnetic resonance image. B, Axial T1-weighted fat saturation. C, Axial apparent diffusion coefficient imaging. D, Intraoperative image.

A teenage girl presented with a 3-month history of a gradually enlarging soft palate mass associated with a change in her voice. She had no associated pain, difficulty swallowing, or difficulty breathing. She was otherwise healthy, with no medical or surgical history. Findings from her physical examination were unremarkable with the exception of a 2 × 2-cm firm, nontender, submucosal posterior soft palate mass just left of the uvula. Quiz at There was no overlying ulceration or discoloration. jamaotolaryngology.com Flexible nasopharyngoscopy was normal. Prior to presentation, a computed tomographic scan and biopsy had been performed at an outside hospital. Magnetic resonance imaging (MRI) of the face with contrast was also performed (Figure, A-C). Imaging showed a well-circumscribed solid lesion with no evidence of infiltration of soft-tissue structures, the pterygopalatine fossa, or palatine nerve foramina. There was no cervical lymphadenopathy. The lesion was resected via a transoral approach and was easily dissected from the surrounding tissue (Figure, D). The overlying mucosa was spared.

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WHAT IS YOUR DIAGNOSIS?

A. Mucoepidermoid carcinoma B. Pleomorphic adenoma C. Hemangioma D. Granular cell tumor

(Reprinted) JAMA Otolaryngology–Head & Neck Surgery April 2015 Volume 141, Number 4

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Clinical Review & Education Clinical Challenge

Diagnosis B. Pleomorphic adenoma

Discussion Of all salivary gland neoplasms, only 3% to 5% occur in children and adolescents.1 These lesions may be benign or malignant and may show epithelial/myoepithelial, mesenchymal, or mixed differentiation. Pleomorphic adenoma (PA), also known as “benign mixed tumor,” is benign and shows a mixture of epithelial/myoepithelial and mesenchymal elements. It is the most common benign minor salivary gland tumor in children. A review of the literature by Ritwik and Brannon2 demonstrated that PA represented 42 of 49 pediatric benign minor salivary gland tumors (85.7%), with myoepithelioma, cystadenoma, and sialadenoma papilliferum accounting for the remainder. The female to male ratio was 2.8:1, the mean age was 12 years, the mean size was 2.4 cm, and the palate was the most common minor salivary gland location. These lesions typically presented as a painless, firm, submucosal mass.2 The differential diagnosis for a mass in a child’s soft palate includes benign and malignant salivary gland tumors, hemangioma, granular cell tumor, hematolymphoid tumors, and metastases. Radiologic imaging narrows the differential by defining an intraglandular vs extraglandular location, detecting malignant features, and assessing local extension, invasion, and nodal metastasis. The mass in the patient described herein was centered in the soft palate and completely separate from the hard palate, effectively excluding consideration of odontogenic and other lesions with a propensity for bone. This made the most likely diagnosis that of a minor salivary gland neoplasm, with pleomorphic adenoma being most common. Extrapolation of imaging data from all salivary tumors (primarily adult parotid tumors) suggests that lesions such as the one seen in this patient, with a marked T2 hyperintensity are typical of a miARTICLE INFORMATION

REFERENCES

Author Affiliations: Department of Otolaryngology and Communication Enhancement, Boston Children’s Hospital, Boston, Massachusetts (Hughes); Department of Neuroradiology, Boston Children’s Hospital, Boston, Massachusetts (Yang); Department of Pathology, Boston Children’s Hospital, Boston, Massachusetts (Vargas).

1. Luna MA, Batsakis JG, el-Naggar AK. Salivary gland tumors in children. Ann Otol Rhinol Laryngol. 1991;100(10):869-871.

Corresponding Author: Amy L. Hughes, MD, Department of Otolaryngology and Communication Enhancement, Boston Children’s Hospital, 333 Longwood Ave, LO-367, Boston, MA 02115 ([email protected]).

3. Motoori K, Yamamoto S, Ueda T, et al. Inter- and intratumoral variability in magnetic resonance imaging of pleomorphic adenoma: an attempt to interpret the variable magnetic resonance findings. J Comput Assist Tomogr. 2004;28(2):233-246.

Section Editor: Rebecca S. Cornelius, MD.

4. Lee YYP, Wong KT, King AD, Ahuja AT. Imaging of salivary gland tumours. Eur J Radiol. 2008;66(3): 419-436.

Published Online: February 12, 2015. doi:10.1001/jamaoto.2014.3722. Conflict of Interest Disclosures: None reported.

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nor salivary gland lesion, such as pleomorphic adenoma (Figure, A).3 The central T2 hypointensity of this lesion may have reflected the microscopically confirmed areas of lesional heterogeneity or sequelae of the prior biopsy. Mucoepidermoid carcinomas, however, may also have T2 hyperintensity with areas of T2 hypointensity, without the overtly aggressive imaging features such as perineural spread or invasion of adjacent structures, resulting in an overlap in appearance with pleomorphic adenoma.4 In the pediatric population, the most common malignant tumors of the minor salivary glands include mucoepidermoid carcinoma and acinic cell carcinoma. Advanced imaging, such as diffusionweighted MRI, can assist with discriminating between benign and malignant minor salivary gland tumors. In this patient, the palate lesion did in fact demonstrate high diffusivity favoring benignity (Figure, C).5 Despite these advanced imaging tools, certainty is difficult in any single case, making surgical excision with pathologic evaluation crucial for diagnosis. Specifically, pleomorphic adenomas contain variable degrees of both salivary duct and cartilage differentiation. Heterologous elements, such as bone or adipose tissue, may also occur.6 Most pleomorphic adenomas harbor a chromosomal translocation involving the PLAG1 or HMGA2 gene, either of which creates an abnormal fusion gene that causes or contributes to dysregulated growth.7 The tumor reported herein had fusion of the PLAG1 gene at chromosome 8q12 with an unknown partner at chromosome 10q14, a previously unreported chromosomal translocation. Treatment of PA of the minor salivary gland is complete excision, which provides both a diagnostic and therapeutic purpose. When discussing the procedure with the patient and family, it is important to consider the risk of recurrence. This risk ranges from 0% to 13%; therefore, long-term follow-up of at least 5 years is recommended.2,8

2. Ritwik P, Brannon RB. A clinical analysis of nine new pediatric and adolescent cases of benign minor salivary gland neoplasms and a review of the literature. J Med Case Rep. 2012;6:287-292.

6. Ellis GL, Auclair PL. Benign epithelial neoplasms. In:Rosai, J, ed. Tumors of the Salivary Glands. Washington, DC: Armed Forces Institute of Pathology; 1996:57-68. 7. Eveson JW, Kusafuka K, Stenman G, Nagao T. Pleomorphic adenoma. In: Barnes L, Eveson JW, Reichart P, Sidransky, eds. World Health Organization Classification of Tumours: Pathology and Genetics of Head and Neck Tumours. Lyon, France: IARC Press; 2014: 254-258. 8. Chau MNY, Radden BG. A clinical-pathological study of 53 intra-oral pleomorphic adenomas. Int J Oral Maxillofac Surg. 1989;18(3):158-162.

5. Habermann CR, Arndt C, Graessner J, et al. Diffusion-weighted echo-planar MR imaging of primary parotid gland tumors: is a prediction of different histologic subtypes possible? AJNR Am J Neuroradiol. 2009;30(3):591-596.

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A pediatric soft palate mass. Pleomorphic adenoma.

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