Facial erythema associated with antinuclear antibody (ANA) positivity frequently prompts referral to Rheumatology due to suspicion of acute cutaneous lupus erythematosus (ACLE). However, patients with systemic lupus erythematosus (SLE) may present with malar rash that clinically overlaps with rosacea. Because these conditions differ substantially in pathophysiology, prognosis, treatment, and follow-up requirements, distinguishing between them is essential for accurate diagnosis and management. This review summarizes the key clinical, dermoscopic, and histopathological features that aid in differentiating rosacea from ACLE. Correct differentiation between rosacea and ACLE is critical because rosacea is primarily managed with trigger avoidance, topical therapies, and oral antibiotics, whereas ACLE often requires immunosuppressive therapy and long-term systemic monitoring. Misdiagnosis may therefore result in either unnecessary immunosuppression or delayed treatment of systemic autoimmune disease.