Salivary gland epithelial neoplasms in pediatric population: a single-institute experience with a focus on the histologic spectrum and clinical outcome.

Salivary gland epithelial neoplasms are rare in children and adolescents, with only a handful of large series having been published. A retrospective study was conducted for 57 cases in patients 20 years or younger. The tumors were located in the parotid (n=36), submandibular gland (n=7), and minor salivary glands (n=14). Nineteen (33%) tumors were pleomorphic adenoma, whereas the remaining (67%) were malignant. The histologic types of carcinomas were mucoepidermoid carcinoma (MEC, n=19, 33%), acinic cell carcinoma (n=7, 12%), adenoid cystic carcinoma (n=6, 11%), secretory carcinoma (mammary analogue) (SC, n=4, 7%), and myoepithelial carcinoma (n=2, 4%). Ninety-three percent (13/14) of the minor and 58% (25/43) of the major salivary gland tumors were malignant. A 7-year-old girl (2%) with a high-grade MEC died from her disease because of uncontrollable locoregional recurrence. Seven patients (16%) developed recurrence including 2 distant metastases from adenoid cystic carcinoma and 6 locoregional recurrences (2 pleomorphic adenomas, 1 SC, 1 myoepithelial carcinoma, 1 adenoid cystic carcinoma, and 1 MEC). The following parameters were associated with decreased disease-free survival in malignant tumors: elevated mitotic index of >4/10 high-power fields (log-rank test, P<.001), and advanced American Joint Committee on Cancer pT (P=.029) and pN stage (P<.001). In conclusion, myoepithelial carcinoma and SC can occur in the pediatric population and should be considered in the differential diagnosis. Salivary gland malignancies in children appear to have better clinical outcome, associated with a 10-year recurrence-free survival rate of 74% and a 10-year disease-specific survival of 94%.