Low-grade adenocarcinoma of the oral cavity: polymorphous or papillary?

Polymorphous low-grade adenocarcinomas are low-grade malignant salivary-gland neoplasms with a broad variety of architectural patterns. Whether papillary structures fall within this spectrum or whether they should lead to a diagnosis of papillary low-grade adenocarcinoma is a subject of debate. This problem was investigated by analyzing a series of 22 salivary gland neoplasms. It was concluded that papillary structures form part of the histologic spectrum of polymorphous low-grade adenocarcinoma but that there are also tumors with papillary structures as a single component. In most instances these are more properly classified as papillary cystadenocarcinomas. As the designation papillary low-grade adenocarcinoma has been used for polymorphous low-grade adenocarcinomas with papillary structures as well as for papillary cystadenocarcinoma, it is advocated that the diagnosis of papillary low-grade adenocarcinoma should be discontinued.