Acinic Cell Carcinoma : Papillary-Cystic
Acinic cell carcinomas display a variety of growth patterns such as solid, follicular, microcystic, and papillary-cystic. In papillary-cystic pattern, there are variably-sized cystic spaces with papillary projections arising from the cyst wall. The cyst lumen is often filled with eosinophilic proteinaceous material. Sometimes the epithelial proliferation may be seen freely floating in the cyst space (as shown here).