Intraductal Oncocytic Papillary Neoplasm of the Pancreas

Definition

Cystic lesion of the pancreatic ducts containing papillary proliferations of oncocytic cells

Compact cell type intraductal papillary mucinous neoplasm (IPMN)
IOPN
Considered by WHO 2010 to be a subtype of IPMN
- Lack of KRAS mutation suggests an independent entity

Unilocular or multilocular cysts formed by dilated ducts
- Communication with ducts may be difficult to identify
Variably complex intraluminal papillary proliferations
- Usually complex arborizing branching
- Usually with thin fibrovascular cores
Lining ranges from simple to stratified to fused solid areas
- Non-papillary areas lined by flattened or cuboidal epithelium
Cysts and papillae lined by oncocytic cells
- Oxyphilic granular cytoplasm
- Scattered goblet cells frequently seen
Intracytoplasmic lumens frequent
- Lumens in solid areas create a cribriform pattern
Large round uniform nuclei
- Prominent nucleoli
- Mitotic figures may be up to 5/hpf
Paucicellular stroma
- Frequently hyalinized
Infrequent findings
- Psammoma bodies
- Focal squamous metaplasia
- Acellular mucin lakes
- Focal severe cytologic atypia
Locally invasive carcinoma reported in 2/11 cases
- Composed of similar cells
- No cancer related deaths yet reported
Age range 39-78

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342