Intraductal tubulopapillary neoplasm of the bile ducts

Intraductal tubulopapillary neoplasms of the bile ducts are rare intraluminal masses forming pre-invasive biliary neoplasms with no mucin production. 

Epidemiology

Intraductal tubulopapillary neoplasm of the bile ducts are rare tumors of unknown incidence, found more frequently in women at their 60s ^1,2. 

Pathology

These tumors are postulated as the counterpart of the pancreatic intraductal tubulopapillary neoplasms ².

Macroscopic appearance

On gross specimen, the lesions are seen as single or multiple intraductal tan granular nodules within a dilated bile duct. When an invasive component is present, it is shown as an infiltrative white scirrhous area within the liver parenchyma, of firm consistency ². 

Microscopic appearance

The intraductal polypoid masses are usually covered by the bile duct epithelium and show a characteristic tubular pattern of intraductal tubulopapillary neoplasm with solid tubular areas ². 

Immunophenotype

They typically express the mucin glycoproteins MUC1 and MUC6 and do not express MUC2 and MUC5AC ¹.

Radiographic features

On imaging, intraductal tubulopapillary neoplasm of the bile ducts present as intraductal soft tissue masses that are usually larger than the ones seen in intraductal papillary neoplasms of the bile duct (IPNB), and are not associated with downstream biliary tree dilatation given its lack in mucin production ¹. The mass is usually associated with upstream biliary tree dilatation and focal liver atrophy/hepatic capsule retraction. 

CT

Postcontrast CT images show tumor enhancement and patchy enhancement within the liver parenchyma surrounding the dilated ducts ¹. 

Treatment and prognosis

Metastatic disease has been described involving the lungs, duodenum, peritoneum, and retroperitoneum ^1. 

Although the studies series on this condition are still scarce, intraductal tubulopapillary neoplasms are believed to have a worse prognosis compared to intraductal papillary neoplasms of the bile duct but better compared to cholangiocarcinoma ¹.