Differentiating MCTD, UCTD, and Overlap Syndrome

Diagnostic Criteria and Features

• The presence of high-titer anti-U1-RNP antibodies is required for MCTD diagnosis, distinguishing it from other entities, with major organ involvement including interstitial lung disease (ILD) and pulmonary hypertension 1, 4
• MCTD diagnosis requires baseline HRCT and PFTs at diagnosis, with PFTs every 6 months for SSc phenotype, according to clinical guidelines 4
• UCTD represents patients with CTD features insufficient to meet classification criteria for any specific disease, with a generally favorable prognosis and limited organ involvement 2, 3
• The epidemiology of ILD in CTD is difficult to determine specifically due to undefined classification criteria and UCTD, with variable autoantibodies and clinical presentation 2, 3

Treatment Approach

• Mycophenolate is preferred for ILD in MCTD, with immunosuppression based on manifestations, while UCTD treatment is conservative, focusing on symptom management and avoiding aggressive immunosuppression 2, 4