Clear cell carcinoma of the pancreas: an adenocarcinoma with unusual phenotype of duct cell origin.

Although clear cell carcinoma has been found in various organs, only six cases have been reported in the pancreas. Moreover, the histogenesis of clear cell carcinoma of the pancreas remains controversial. We report a case of clear cell carcinoma of the pancreas in a 61-year-old woman, with an unusual pheno- or genotype detected by histochemical, immunohistochemical, and K- ras oncogene analyses. Histologically, the pancreatic tumor was predominantly composed of clear cell nests with scanty fibrous stroma and scattered duct-like structures. Neither clear cell nor duct-like components of the tumor showed mucin production. Immunohistochemical analysis of neoplastic cells showed a positive reaction to antibodies against cytokeratins 8 and 19, carbohydrate antigen 19-9, and alpha-1-antitrypsin, and showed no reaction to antibodies against carcinoembryonic antigen, neuroendocrine markers, trypsin, amylase, and HMB45. K- ras analysis revealed no mutation at codon 12 in either clear cell or duct-like components. The patient has had no recurrence as yet. The pancreatic carcinoma in our patient may be of duct cell origin, but the results of histochemical, immunohistochemical, and gene analyses and patient's outcome were unusual compared with those of previous cases.