Clear-cell Variant of Mucoepidermoid Carcinoma Presenting as a Palatal Mass in a 10-Year-old Boy

Abstract

Background: The clear-cell variant of mucoepidermoid carcinoma (MEC) involving minor salivary glands is extremely rare in children.

Case report: We report a case of clear-cell variant MEC in the minor salivary gland in a 10-year-old boy who presented with a mass of the right hard palate. Fine-needle aspiration showed features suggestive of clear-cell variant of MEC. Microscopically, the tumor cells showed predominant clear cells and scattered mucous cells. There was increased mitotic activity (6/mm²). No tumor necrosis or nuclear pleomorphism was identified. The tumor cells were positive for cytokeratin 7 (CK7), tumor protein p63, P40 (ΔNp63), CK5/6 and mucicarmine. Rearrangement of mastermind-like transcriptional coactivator 2 (MAML2) (11q21) gene was present in the tumor cells by fluorescence in situ hybridization, supporting the diagnosis of an intermediate-grade clear-cell variant of MEC. A right infrastructure maxillectomy for palate carcinoma with negative margins was performed. Grossly, the tumor was a 2.1 cm well-circumscribed, friable, pale tan mass with focal areas of cystic change. The final pathological diagnosis was clear-cell variant of MEC, intermediate grade, pT2. Post surgery, the patient recovered and was doing well, with no tumor recurrence or metastasis at the 6-month follow-up.

Conclusion: To the best of our knowledge, this is the first documented case of clear-cell variant MEC in a child. Due to low to intermediate tumor grade, an overtly aggressive treatment should be avoided in a child.

Keywords: Child; MAML2 rearrangement; clear-cell variant; fluorescence in situ hybridization; minor salivary gland; mucoepidermoid carcinoma.