What is classed as a enlarged lymph node ?

Sometimes >1 cm: On ct scans, sometimes >1 cm is called enlarged, but in certain parts of the body 6-9mm may be called enlarged, when radiologists are looking for cancer. An important question is why is the lymph node the size it is, whether it is 8mm, 18mm, or 28mm. For example, in normal children, many of them have neck lymph nodes 1 cm or bigger.

Monitoring Centers: Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells and digested food. Lymph nodes "taste" the lymph for anything bad like bacteria/viruses/cancers, etc. When it detects a problem, it alerts the immune system and your body reacts. They enlarge in response to the inflammation they create when they react. They shrink when all is well.