In some cases, lymphomas that start or grow in the abdomen can cause swelling or pain in the belly area. This might be from lymph nodes that have become large, or from organs such as the spleen or liver that have become involved with disease. Fullness in the abdomen can also result from a build-up of large amounts of fluid in the abdomen. An enlarged spleen might press on the stomach, which can cause a loss of appetite and feeling full after only a small meal. Lymphomas in the stomach or intestines can also cause abdominal pain, nausea, or vomiting.