Retroperitoneal fibrosis, methysergide and malignant lymphoma.

A patient who developed retroperitoneal fibrosis on low dose continuous methysergide therapy is presented. Discontinuing the drug led to rapid clinical improvement but the patient was subsequently found to have disseminated malignant lymphoma. This may have had a synergistic effect with methysergide in producing retroperitoneal fibrosis. The patient had also previously had thyrotoxicosis but no evidence of a continuing autoimmune process was found.