Clear cell ductal adenocarcinoma of pancreas: a case report and review of the literature.

We present a unique carcinoma of the pancreas with predominantly clear cell morphology (>95% clear cells). Mucicarmine stain revealed abundant intraluminal and intracytoplasmic mucin. Immunohistochemically, the cells were positive for the epithelial markers cytokeratin 7 and CAM 5.2, and were focally positive for cytokeratin 20. These cells also expressed monoclonal carcinoembryonic antigen. Stains for the neuroendocrine markers synaptophysin and chromogranin were negative, as were stains for vimentin, p53, HMB-45, and CD10. An additional outstanding feature was the presence of dense intraluminal and intracytoplasmic hyaline globules, which were immunohistochemically positive for alpha1-antitrypsin. Sequencing of the K-ras oncogene revealed a point mutation in codon 12, providing molecular evidence of ductal origin. In the proper morphologic context supported by immunohistochemistry, clear cell carcinoma can be regarded as a rare variant of ductal adenocarcinoma.