Pancreatic intraductal tubulopapillary neoplasm

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

Epidemiology

Incidence/prevalence is unclear. Small series show an even male:female distribution and an average age of presentation of 58 years old .

Clinical presentation

Nonspecific. Presents similarly 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, intraductal papillary mucinous neoplasm (IPMN), and intraductal variant of pancreatic acinar cell carcinoma.

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

  • positive for cytokeratin 7 and/or cytokeratin 19
  • negative for trypsin, MUC2, MUC5AC, and fascin.
  • aberrant expression of b-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
    • 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
  • 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 are still alive after pancreaticoduodenectomy.

Differential diagnosis