About the Gallbladder

The gallbladder is a small, pear-shaped organ located underneath the right lobe of the liver. Both the liver and the gallbladder are underneath the right lower ribs. The gallbladder is usually about 3 to 4 inches long and normally no wider than 1 inch. The gallbladder concentrates and stores bile, a fluid produced in the liver that helps digest fats in the small intestine. Bile may be released from the liver directly into the small intestine, or stored in the gallbladder and released later. When food is being digested, the gallbladder contracts and releases bile into the small intestines through a passageway called the common bile duct.

Types of Gallbladder Tumors

Most gallbladder cancers are adenocarcinomas. An adenocarcinoma is a cancer beginning in the cells that line many internal and external surfaces of the body, including the inside of the digestive system. There are other types of cancer that may develop in gallbladders, but these are uncommon.

Gallbladder cancers whose cells grow along a finger-like skeleton of connective tissue and blood vessels are called papillary cancers. In general, papillary cancers are not as likely to invade the liver or nearby lymph nodes. They tend to have a better prognosis (outlook) than most other kinds of gallbladder cancers called non-papillary adenocarcinomas. More than 75% of gallbladder adenocarcinomas are nonpapillary adenocarcinomas. About 6% of all gallbladder cancers are papillary adenocarcinomas, and almost all the rest are mucinous adenocarcinomas, adenosquamous carcinomas, squamous cell carcinomas, or small cell carcinomas.

Gallbladder cancers are graded by how closely they look like normal (non-cancerous) gallbladder tissue when viewed under a microscope. Low-grade cancers more closely resemble normal gallbladder tissue. High-grade cancers are made up of cells that look very different from normal gallbladder tissue. Typically, low-grade cancers are less likely to spread outside the gallbladder than high-grade cancers, and have a more favorable outlook. Intermediate grade cancers have an appearance and prognosis between that of low- and high-grade cancers.

Revised: 08/06/2006