Table 2.

Summary of morphologic features and altered genes of pancreatic ductal adenocarcinoma subtypes

Subtype	Colloid	Medullary	Adenosquamous	Hepatoid	Signet ring cell
Morphologic features	More than 80% of extracellular mucin; focal signet-ring cells can be seen	Minimal glandular differentiation; syncytial growth pattern; abundant inflammatory infiltrate	More than 30% of squamous differentiation	More than 50% of hepatocellular differentiation	More than 80% of signet ring cell component
Altered genes	GNAS; ATM	MMR genes; POLE	SMAD4; CDKN2A	BAP1; Notch1	NA

MMR: Mismatch repair; NA: Not available.