Intraductal tubulopapillary neoplasm of pancreas with stromal osseous and cartilaginous metaplasia; a case report.

Recently, a surgically resected case of intraductal tubulopapillary neoplasm (ITPN) with stromal osseous and cartilaginous metaplasia was encountered. A CT scan showed calcification at the tail of the pancreas two years before the operation. In the resected specimen, macroscopically, the main pancreatic duct was dilated and filled with a whitish solid mass without mucinous material. The tumor showed mainly a solid and papillary growth pattern. The tumor cells had no evidence of acinar differentiation. The tumor cells, at the tail of the pancreas, invaded focally to surrounding pancreatic parenchyma with stromal desmoplastic and fibrosclerotic reaction and also formed nodular stromal osseous and cartilaginous metaplasia. The tumor did not invade extrapancreatic tissue and showed no lymph node metastasis. As there were no signs of chronic calcifying pancreatitis, it is hypothesized that the metaplastic stroma was formed by a stromal reaction due to the tumor growth. It is thought, therefore, that the intraducal component of the tumor had existed at least for two years. This case suggests that ITPN is a relatively indolent tumor with a better prognosis than that of other types of invasive ductal adenocarcinoma of the pancreas.