colorectal signet ring cell adenocarcinoma
Friday 15 February 2013
In contrast to that in the stomach, signet ring cell adenocarcinoma is rare in the colorectum, representing <1% of all colorectal carcinomas.
Similar to mucinous carcinoma, signet ring cell carcinoma is defined by the presence of >50% of tumor cells showing signet ring cell features characterized by a prominent intracytoplasmic mucin vacuole that pushes the nucleus to the periphery.
Signet ring cells may show an infiltrative growth pattern or are present within the pools of extracellular mucin.
By definition, signet ring cell carcinoma is poorly differentiated (high grade) and carries a worse outcome than conventional adenocarcinoma.
However, some signet ring cell carcinomas may be MSI-H tumors and thus may behave as low grade tumors biologically.