Yes. There's a list of 11 criteria to help diagnose sle. A person needs to satisfy at least 4 out of the 11 criteria before the diagnosis can be pinpointed. Of the 11 criteria, 7 relate to symptoms, and 4 have to do with lab tests. So it is possible to make a diagnosis of sle with just clinical symptoms as long as you have at least 4 from the list.
Need lab work. Blood work is needed to confirm the diagnosis.