American Board of Internal Medicine (ABIM) Certification Practice Exam

Which syndrome includes features of systemic lupus erythematosus, systemic sclerosis, and/or polymyositis with positive anti-U1-ribonucleoprotein antibodies?

1. Rheumatoid Arthritis

2. Mixed Connective Tissue Disease

3. Systemic Sclerosis

4. Systemic Lupus Erythematosus

The correct answer is: Mixed Connective Tissue Disease

The correct answer is Mixed Connective Tissue Disease, which is characterized by overlapping features of systemic lupus erythematosus, systemic sclerosis, and polymyositis. A key distinguishing feature of this syndrome is the presence of positive anti-U1-ribonucleoprotein antibodies, which are associated with it. Mixed Connective Tissue Disease presents with a unique combination of symptoms from the aforementioned diseases, such as joint pain, muscle weakness, skin changes, and other systemic manifestations. The presence of anti-U1-ribonucleoprotein antibodies specifically indicates this overlapping condition rather than the individual diseases themselves, which have their own distinct antibody profiles and clinical presentations. While rheumatoid arthritis, systemic sclerosis, and systemic lupus erythematosus are all distinct conditions that may share certain symptoms, they do not typically include the combination of features seen in Mixed Connective Tissue Disease accompanied by the specific antibody profile. Thus, recognizing the features of Mixed Connective Tissue Disease and its associated antibodies is crucial for accurate diagnosis and management of patients presenting with these overlapping symptoms.