Adenosquamous Carcinoma and Pure Squamous Cell Carcinoma of the Pancreas: Report of two Cases.

Adenosquamous carcinoma (ASC) and pure squamous cell carcinoma (SCC) of the pancreas are very rare diseases. The author herein reports two cases of ASC and SCC of the pancreas. The first case is ASC. An 80-year-old woman was admitted to our hospital because of abdominal pain and weakness. Imaging modalities including CT, MRI and ERCP revealed a pancreatic body tumor. Distal partial resection of the pancreas and splenectomy were performed. Grossly, an infiltrative solid tumor measuring 3 × 4 × 4 cm was present in the pancreatic body. Histologically, it was an ASC consisting of poorly differentiated adenocarcinoma element (20% in area) and SCC element (80%). There was a gradual transition between the two. Many perineural invasions and lymphovascular permeations were recognized. The patient died of systemic metastasis five months after operation. The second case is an SCC. A 69-year-old woman presented with abdominal pain and jaundice. Imaging modalities including CT, MRI and ERCP revealed a tumor in the head of the pancreas. Pancreaticoduodenectomy was performed. Grossly, an infiltrative solid tumor measuring 5 × 5 × 6 cm was present. Histologically, the tumor was pure SCC. The SCC was moderately differentiated SCC. A large number of perineural invasions and lymphovascular permeations were present. The patient died of systemic metastasis three months after operation. The author speculates that ASC of the pancreas may be derived from squamous tansdifferentiation of adenocarcinoma element or from pluripotent stem cells, and that SCC of the pancreas may arise from malignant transformation of squamous metaplasia of pancreatic ducts or from pluripotent stem cells.