Calcification is the accumulation of calcium in body tissues. Although this normally occurs in bone formations, it can occur in soft tissue, which causes the tissues to harden. Calcified lymph nodes are found commonly in abdominal x-rays but are asymptomatic and are usually ignored, notes the Radiology Masterclass. Despite this, lymph nodes found in the mediastinal area of the body can be quite dangerous.
According to Radiopaedia, potential causes of mediastinal lymph nodes include: infection granulomatous diseases, sarcoidosis, silicosis, or treated lymphoma. More uncommon causes include: pneumocystis carinii or jerovecii pneumonia, metastases, amyloidosis, sclerdoerma, and Castleman disease.
Calcified lymph nodes may develop over an area affected by pathological calcification. A radiologist can compare a current image with older x-rays, if they are available to determine whether there is any importance to the calcified lymph node.
According to HealthTap, calcified lymph nodes can be felt while the lymphatic system is doing its job. The lymphatic system carries things through the body that are too large to be carried through the arteries and veins. The lymph nodes try to detect anything bad that passes through them, such as bacteria, viruses, or cancer. If it detects something dangerous, the immune system will react to that lymph node. The lymph node will enlarge as part of its response to this detection. If the lymph node is calcified, it will feel hard.