Autoimmune diseases were poorly understood in the past leading to a spike of new diagnoses and treatments. One of the main manifestations of many autoimmune diseases is enlarged lymph nodes because of the rise of chemical mediators released to the bloodstream. They push the entire immune system to increase the number of cells. In turn, they also release new mediators in a vicious cycle that destroys many organ systems. In this scenario, enlarged lymph nodes are basically formed by those immune cells. All autoimmune diseases have the potential of causing enlarged lymph nodes. The most common are systemic lupus, rheumatoid arthritis and sarcoidosis.
Autoimmune diseases affect the whole body, and therefore many lymph nodes will be enlarged, including the occipital lymph nodes. Your doctor will perform a general examination and will order a battery of investigations which may include taking a biopsy to confirm the diagnosis. Autoimmune diseases are treated in a very different way than any other condition affecting the lymph nodes, and a mistreatment can lead to severe conditions.