Adenosquamous carcinoma of the pancreas: preoperative diagnosis and molecular alterations

Adenosquamous carcinoma of the pancreas is a rare tumor which has a less favorable prognosis than common ductal cell carcinoma of the pancreas, and a definite preoperative diagnosis of this tumor is quite difficult. We herein report two cases of this rare variant. The patients were a 41-year-old man (patient 1) and a 67-year-old woman (patient 2). Patient 1 had a hypoechoic mass measuring 3 cm in the uncus of the pancreas, while patient 2 had a huge mass, measuring 8 cm, in the tail of the pancreas. Patient 2 was successfully diagnosed preoperatively as having an adenosquamous carcinoma, by cytological examination of the pure pancreatic juice obtained by endoscopic retrograde pancreatic juice aspiration. A pylorus-preserving pancreatoduodenectomy was performed for patient 1, and a distal pancreatectomy with resection of the spleen and the left kidney was performed for patient 2. Subsequent pathological findings of these two tumors revealed adenosquamous carcinoma of the pancreas. K-ras point mutation, p53 overexpression, and telomerase activity in both tumor specimens were detected by the mutant allele specific amplification method, immunohistochemical staining, and telomeric repeat amplification protocol assay, respectively. The two patients died of recurrent disease 5 and 4 months, respectively, after surgery. Cytological examination of pure pancreatic juice is a useful modality for the preoperative diagnosis of this tumor, and frequent molecular alterations may be associated with the poor prognosis of adenosquamous carcinoma of the pancreas.