Clear cell carcinoma of the stomach: a rare tumor variant imparting poor prognosis.

Clear cell gastric cancer (CCGC) represents an extremely rare variant of adenocarcinoma of the stomach. It can be mistaken for a clear cell metastatic lesion arising from other anatomic parts, especially renal cell carcinoma. We describe the case of a 66-year-old woman who was operated for a pyloric adenocarcinoma which resulted to be a CCGC at definitive histology. Moreover, we offer a systematic review of the current pertinent literature on CCGC. Our case represents the 160th example of CCGC. Clear cell aspect is due to the intracytoplasmic accumulation of glycogen in most cases, followed by mucin, lipid or water; the reason of the underlying biochemical process is still unclear. Paralleling other epithelial clear cell malignancies (as ovarian, bladder, urothelial or pancreatic cancers), also CCGC shows a more aggressive clinical behavior over conventional neoplastic counterparts. Differently from clear cell carcinomas involving other organs, CCGC has been rarely investigated by the literature. Since, compared to non clear cell cancers, this particular phenotype of gastric cancer appears to be associated with poorer prognosis, further studies are needed in order to corroborate its real adverse prognostic significance and standardize the correct management and treatment.