Pancreatic intraductal tubulopapillary neoplasm

Pancreatic intraductal tubulopapillary neoplasms (ITPNs) are rare variants of intraductal papillary neoplasms. Unlike an IPMN, an ITPN does not produce mucin.

Epidemiology

The prevalence is unclear. Small series show no gender predilection and an average age of presentation of 58 years old ¹.

Clinical presentation

The clinical presentation is non-specific and similar to other pancreatic tumors, with signs/symptoms depending on the location of the tumor. They demonstrate high-grade atypia.

Pathology

According to the WHO criteria, ITPN is a subtype of intraductal tubular neoplasms (ITN). Histologically, these tumors are distinct from pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and the intraductal variant of pancreatic acinar cell carcinoma.

Tumor cells form tubulopapillae and contain little cytoplasmic mucin. There is also an absence of acinar differentiation.

• positive for cytokeratin 7 and/or cytokeratin 19

• negative for trypsin, MUC2, MUC5AC, and fascin

• aberrant expression of β-catenin is not observed

Radiographic features

Like a main-duct IPMN, an ITPN demonstrates a dilated and irregular main pancreatic duct, but without an abundance of low-attenuation mucin.

• a "two-tone duct" or "cork-in-bottle" sign has been suggested ²

  • a soft-tissue attenuation "cork" in the main pancreatic duct plugs the lower attenuation pancreatic fluid

• main pancreatic duct distal to the tumor is dilated

CT

• the intraductal tumor is isoattenuating or mildly hyperattenuating relative to surrounding pancreatic parenchyma

• the tumor is relatively hypoattenuating after contrast administration

MRI

• T1: tumor is mildly hypointense

• T2: tumor is mildly hyperintense

• MRCP: tumor fills main pancreatic duct like a "cork"

Treatment and prognosis

Because of the rarity of the tumor, treatment and prognosis are not well established. In one series, 8/10 patients were still alive after pancreaticoduodenectomy.

Differential diagnosis

• pancreatic ductal adenocarcinoma: may invade retroperitoneal structures, ITPN is not known to do this

• intraductal extension of a pancreatic neuroendocrine tumor

• pancreatic acinar cell carcinoma