A classic symptom of systemic lupus erythematosus is which of the following?

A butterfly rash across the nose is a hallmark sign of systemic lupus erythematosus (SLE). This rash, also known as a malar rash, typically appears as a symmetrical, reddish or purplish rash across the cheeks and bridge of the nose, resembling the shape of a butterfly. It is considered one of the characteristic features of SLE and reflects the autoimmune nature of the disease, as it is related to inflammation caused by the immune system attacking the body’s own tissues.

In contrast, while dry patches on elbows, scaly skin on the face, and redness in specific joints can occur in various skin or autoimmune conditions, they are not specific or classic indicators of systemic lupus erythematosus. The butterfly rash is distinctive and widely recognized in clinical practice as being associated with SLE, making it a key symptom for diagnosis.