Mucoepidermoid Carcinoma Presented as a Lymph Node Metastasis in 9-Year-Old Child: A Case Report.

Salivary gland neoplasms are rare in pediatric and adolescent populations. Mucoepidermoid carcinoma (MEC) is the most common malignant neoplasm of the salivary glands that most frequently arises in the parotid gland as a painless swelling. Herein we present a rare case of MEC in a child with metastasis to the cervical lymph node as primary presentation. A nine-year-old female without significant past medical history presented with a neck mass behind the ear for two months. Imaging study showed a heterogeneous soft tissue mass with a radiologic impression of a suppurative lymph node with surrounding lymphadenopathy. Histological sections of the lymph node showed metastatic carcinoma formed of sheets of epidermoid-looking cells and scattered mucin producing cells (mucocytes). Immunohistochemistry (IHC) study showed that the tumor cells were diffusely positive for Pan-Cytokeratin, p40, and p63 with focal Mucicarmine expression. Follow up positron emission-computed tomography (PET-CT) scan showed a right parotid gland mass-like lesion. MECs are presented in either major or minor salivary glands. The primary presentation of MEC in children and in lymph node is extremely rare. Although the IHC and molecular profiling of the MECs in the pediatric population shows similarities to those tumors observed in the adult population, the overall prognosis in the pediatric group is excellent with approximately 95% five-year overall survival rate.