Immunohistochemical and genetic features of mucinous and signet-ring cell carcinomas of the stomach, colon and rectum: a comparative study.

Gastric and colorectal cancers are prevalent and fatal cancers worldwide. Although mucinous adenocarcinoma (MAC) and signet-ring cell carcinoma (SRCC) are relatively uncommon, they are of critical importance because of poor prognosis. In Turkey, studies on MSI and other molecular characteristics in mucinous adenocarcinoma (MAC) and signet-ring cell carcinoma (SRCC) of stomach and colon have not been conducted. The present study aimed to investigate the similarities and differences between gastric/colorectal MACs and SRCCs. A total of 590 patients with gastric carcinoma and 1075 patients with colorectal carcinoma, in whom pathologic diagnosis was made within a period of 8 years in our hospital, were retrospectively evaluated. Tissue blocks and slides obtained from the pathology archive were used for immunohistochemical and genetic studies and for microscopic re-evaluation according to the WHO criteria. Data from a total of 135 patients, of whom 78 had been diagnosed with MAC and 57 had been diagnosed with SRCC, were analyzed. MAC patients were significantly older than those with SRCCs. While colorectal localization was more common among MACs, SRCC patients mostly showed gastric localization. Macroscopically, ulceroinfiltrative type was the most prevalent in both groups followed by fungating type in MAC and infiltrative type in SRCC. When compared with SRCC group, MAC group was associated with higher tumor invasion stage, lower rate of patients with infiltrative growth pattern and perineural invasion, and less frequent lymph node invasion. More effective approaches will be developed in the treatment and prevention of cancer along with more data about the incidence, pathogenesis, prognostic factors, and clinical course of cancers.