Cancer is commonly associated with the term “tumor”. Although this association is not scientifically accurate, it does picture one of the forms of cancer, similar to a swelling. Swollen organs have a chance of becoming cancerous. After all, cancer is nothing but an unchecked division of cells. Regarding lymph nodes, they can be affected by cancer in 2 ways. Firstly, if cancer originated within their tissues or within blood cells, and secondly, if cancer originated in the territory they drain, and cancer cells were filtered through lymph channels and became dislodged within the lymph nodes and continued dividing, this condition is called a “metastatic cancer”. Although both conditions are broadly known as cancer, their management and outcome vary greatly.
An important aspect to consider is how to differentiate between a cancerous and an inflammatory lymph node. The common saying is that “if it hurts, it’s good”. While this is largely true, it can’t be used as a general rule. Some cancerous lymph nodes can be infected or may even be painful without infection, especially in late stages of the disease. The other more important aspect is the clinical examination. Cancerous lymph nodes feel harder and are less mobile than inflammatory lymph nodes. Again, there are no absolutes, and in some cases of Hodgkin’s lymphoma, lymph nodes are rubbery. If the diagnosis proves challenging via history and clinical examination, your doctor may order a biopsy or an ultrasound, ideally both.
Generally speaking, if a metastatic cancer occurs, it usually affects a limited number of lymph nodes and most or all of them are within the same line of drainage, whereas lymphoma “cancer of the lymph nodes” and leukemia “blood cancer” usually involve many non-neighboring lymph nodes. A very thorough examination of the area drained by the affected group of lymph nodes is required. In case of occipital lymph nodes, the most likely culprit in cancer is a squamous cell carcinoma of the scalp. It looks like an ulcer or a non-healing wound. Another cancer that may spread to the lymph nodes from the scalp is melanoma, a cancer originating from melanocytes, the cells responsible for the color of your skin. The presence of lymph node involvement in skin cancer changes its management and its classification. We call it a “stage”. When cancer involves a greater area, a neighboring organ or even spreads to other parts whether through lymphatics or blood, we advance its stage and change its treatment accordingly.