Is lupus a syndrome or a disease?

Does it matter whether we call lupus a disease or a syndrome? Because both conditions can be rigorously defined, this has little effect on uniformity of entry criteria for clinical trials. However, because diseases are the product of a single pathophysiologic mechanism, and syndromes are not, whether lupus is a disease or a syndrome does have broad ramifications. For example, looking for the "cause" or the "cure" for lupus involves a disease-specific conceptual framework, whereas, for syndromes we investigate risk factors and treatment modalities. On the basis of current laboratory data, we contend that lupus is a syndrome and only has candidate status as a disease. This helps to explain heterogeneity in results of studies of therapeutic agents and laboratory investigations of etiology. Patients, funding organizations, and lay support groups need to be aware of this distinction to reduce unrealistic expectations.