17. Feingold's Syndrome as an Unusual Mimic of Rheumatoid Arthritis

Abstract

Background: The growing emphasis in rheumatology is to diagnose and treat inflammatory arthritis earlier in disease course. In this case we present a young woman with established deformity of the hands but no evidence of inflammatory disease highlighting the importance of history and examination in the evaluation of hand deformity and the use of appropriate imaging to confirm or refute rarer diagnoses which may mimic RA. Methods: A 33-year-old lady presented with a gradually progressive hand deformity. The right hand had longstanding deformity but she had recently developed arthralgia and stiffness in both hands. On examination there was bilateral progressive symmetrical deformity in all digits. The stiffness had no diurnal variation and did not improve with movement; there was minimal swelling. Interestingly she had a significant family history with her mother suffering from severe, erosive RA and three of her children, Feingold's syndrome. On assessment she had shortened index and fifth fingers bilaterally, partially correctable swan neck deformities of the fourth and fifth digits and subtle inter-digital webbing, but no joint or soft tissue swelling. Serologically, RF, ANA and anti-CCP antibodies were negative and there were no inflammatory features. There was no evidence of synovitis or tendinopathy on ultrasound. Radiographs showed shortening of the second and fifth fingers middle phalanx, but no erosive disease. Results: Despite her presentation and maternal history, evidence of an inflammatory arthritis was lacking. Local geneticists felt the combination of skeletal manifestations was consistent with previously undiagnosed Feingold's syndrome. Management was conservative with analgesia, occupational therapy and family screening. Conclusion: Feingold's syndrome is an autosomal dominant condition causing defects in the transcription factor MYCN. Abnormalities of the hands and feet occur in 80-90% of patients. Skeletal abnormalities such as brachymesophalangy, hypoplastic thumbs, clinodactyly, brachydactyly of the index and little fingers plus syndactyly of the toes are frequent. Typical characteristics can include microcephaly and a short palpebral fissure. Internal organs can be affected, manifesting with duodenal or oesophageal atresia or cardiac and renal abnormalities. Interestingly, the syndrome shows considerable overlap with the VACTERL spectrum which is defined as vertebral anomalies, anal atresia, cardiac defect, tracheoesophageal, renal and limb abnormalities. VACTERL anomalies may be associated with anti- TNF use during pregnancy although this has yet to be confirmed. Whilst our patients' mother had RA, she had not been exposed to anti- TNF in pregnancy. Feingold's syndrome may therefore produce painful deformity that can mimic RA, due to skeletal abnormalities resulting in ligamentous instability. It is therefore important to consider Feingold's syndrome when evaluating young patients with rheumatoid hands and a family history of hand deformity. Plain radiographs of the hand differentiate between these conditions thereby preventing the unnecessary commencement of treatment with potentially toxic agents.