Non-rheumatic diseases such as malignancy (particularly hematologic), thyroid disease and infections can mimic arthritis and connective tissue diseases. They should be ruled out with further history, physical examination and judicious use of appropriate screening tests. A rheumatological review of systems can help to identify other symptoms that the patient may have.

Though the following may be symptoms and signs of SLE, their presence should alert the clinician to the possibility of other occult diseases:
• Fevers
• Night sweats
• Weight loss of more than 10% of body weight
• Enlarged spleen or lymph nodes
• New heart murmur
• Abnormal hematology profile.