Nonmucinous, glycogen-poor cystadenocarcinoma of the pancreas.

True cystic neoplasms of the pancreas generally have mucinous, glycogen-rich, or acinar-type-cyst-lining epithelium. A malignant polycystic pancreatic neoplasm in a 74-year-old black woman whose cyst-lining epithelium had none of the above-cited attributes and thus appears to represent an exception is described. The primary tumor was a large, encapsulated mass whose cysts contained watery fluid. Basically, two types of epithelium lined the cysts: a single layered, low-grade malignant-appearing type and a proliferative, overtly malignant-appearing pseudostratified and papillary type. Oncocytic metaplasia, canaliculi, and microvilli were ultrastructural features.