A lymphoma arising from the appendix. The majority of lymphomas affecting the appendix represent disease extension from the intestinal wall; primary lymphomas of the appendix are rare. The disease is appendix lymphoma (MONDO_0001237, a Monarch Disease Ontology term). Also known as: appendiceal lymphoma, lymphoma of appendix, lymphoma of the appendix, lymphoma of vermiform appendix, primary appendix lymphoma, vermiform appendix lymphoma.