Yes. It's possible to start off with mild or limited symptoms and only arthritis without systemic lupus. But then the disease could evolve and include many organ systems and become systemic. Important to get evaluated and tested if other symptoms such as fever, fatigue, muscle pain, rash, hair loss also start to occur.
No. An inflammatory arthritis is one component of systemic lupus. In some individuals it may be the only symptom of the disease but that person still has systemic lupus.