Case Studies

 Case 10.10 Mixed connective tissue disease

A 19-year-old typist presented with acute, bilateral arthralgia of her hands, wrists and knees. The pain prevented her from sleeping or typing. On examination, there were no effusions or tenderness of any joints. No diagnosis was made but she was treated symptomatically with indomethacin. Two years later, she developed a mild degree of Raynaud's phenomenon, with a flare-up of the arthralgia and some proximal muscle weakness. On investigation, she had a low haemoglobin (108g/l) but a normal white-cell count and differential. Her ESR was raised (63mm/h), and her serum contained ANA (titre 1/160; speckled pattern) (see Chapter 19). dsDNA binding was normal but antibodies to ENA were detected and found to be largely directed against nuclear ribonucleoprotein (RNP); there were no antibodies to the Sm antigen (see Chapter 19). A latex test for rheumatoid factor was negative. Complement levels (C3 and C4) were normal but she had a raised serum IgG of 21.8g/l (NR 7.2-19.0). X-rays of the hands and knees were normal. There was no proteinuria and her serum creatinine and blood urea were normal.

A diagnosis of mixed connective tissue disease was made and the patient started on a low dose of prednisolone. The pain in her wrists and knees improved dramatically, but attempts to reduce and discontinue the steroids were unsuccessful; severe arthritis returned each time the drug was discontinued. Her Raynaud's phenomenon has slowly worsened and is now associated with progressive sclerodactyly.