Distinction from cystadenoma may be difficult and relies largely on identification of infiltrative growth into salivary parenchyma or surrounding tissues. Review of multiple sections is often helpful. Low-grade mucoepidermoid carcinoma is typically cystic but, unlike cystadenocarcinoma, usually has a wide variety of cell types and areas that are more solid than cystic. The papillary cystic variant of acinic cell carcinoma has focal acinar differentiation and a greater degree of epithelial proliferation. Epidermoid differentiation in cystadeno-carcinomas is rare.
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