A 28-year-old woman has puffy fingers, arthralgia, mild proximal muscle weakness and oesophageal dysmotility. High-titre speckled ANA is present, and high-titre antibodies to U1 ribonucleoprotein are detected. The most likely diagnosis is:

• A Polymyositis
• B Limited cutaneous systemic sclerosis
• C Mixed connective tissue disease ✓
• D Systemic lupus erythematosus

Explanation

Mixed connective tissue disease combines features of SLE, scleroderma and polymyositis, classically beginning with sausage-like puffy fingers, and is defined serologically by very high titres of anti-U1 RNP on a speckled ANA pattern. Each individual disease option explains one feature but not the overlap, and none carries the characteristic extremely high anti-U1 RNP titre that anchors this diagnosis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.