Which finding is consistent with a diagnosis of rheumatoid arthritis?

In the context of rheumatoid arthritis (RA), the finding of a low-grade fever is consistent with this autoimmune condition. RA is characterized by systemic inflammatory processes that can lead to various symptoms including joint inflammation, stiffness, and a general feeling of malaise, which may result in a low-grade fever. This low-grade fever can be attributed to the underlying inflammatory response in the body, as the immune system is active in combating what it perceives as a threat.

The other choices represent signs or features that are more closely associated with other conditions. For example, Janeway lesions are typically related to infective endocarditis, while tophi are associated with gout, characterized by the deposition of uric acid crystals in tissues. Unilateral joint pain is more typical of other types of arthritis, such as osteoarthritis. Therefore, recognizing systemic symptoms like a low-grade fever is key in the assessment and diagnosis of rheumatoid arthritis.