The spread of a malignant neoplasm to the lymph nodes. The disease is Monarch Disease Ontology term MONDO_0005438 (metastatic malignant neoplasm in the lymph nodes). Also known as: Metastases to lymph nodes, metastasis to lymph node, metastatic malignant neoplasm to the lymph nodes, metastatic neoplasm to the lymph node, metastatic tumor to lymph node, metastatic tumour to lymph node.