A tumour deposit is a group of tumour cells outside of the original tumour. A tumour deposit can be found close to the original tumour, or in other organs and body sites far from the original tumour. Another name for a tumour deposit is metastasis.
Tumour deposits are commonly found in lymph nodes, lungs, bones, and the liver. Tumour deposits can also be found in the same organ as the original tumour. In this situation, the deposit is distinct and clearly separated from the original tumour.
Tumour deposits are important because your pathologist will use this information to determine the pathologic cancer stage (pTNM). Specifically, tumour deposits found in lymph nodes close to the original tumour are often used to determine the nodal stage (pN). Tumour deposits found in lymph nodes further from the original tumour, or in another organ (lung, liver, or bone), are frequently used to determine the metastatic stage (pM) of cancer.