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Psoriatic arthritis or could it be Singleton-Merten syndrome?
  1. A Ruffle,
  2. P Desai
  1. Child Health Department, Ipswich Hospital, Ipswich, UK

Abstract

Aims To describe Singleton-Merten Syndrome as an unusual cause of arthritis associated with a psoriasiform rash.

Methods Case report.

Results We present this case of a girl who at 11 months suffered from discrete red scaly areas on the trunk, limbs and scalp. She was given a diagnosis of psoriasis which remained poorly controlled throughout childhood, despite phototherapy and methotrexate treatment.

In infancy, slow gross motor development was noted and felt to be related to hypermobility. She also began complaining of morning stiffness and pain in her hands and knees. The ESR was slightly raised at 17 but all other investigations were negative including ANA, rheumatoid factor and HLA-B27. X-rays showed osteopenic bones but no joint erosion. A diagnosis of psoriatic arthritis was made and although wheelchair bound, she never had significant joint inflammation.

Dental concerns also emerged with delayed eruption and very malformed teeth with short roots. She was of proportional short stature with height at the 3rd centile at 10 years.

At 11 years a systolic murmur was first heard although she had no cardiac symptoms. An echocardiograph revealed a moderately stenosed valve which rapidly progressed with syncopal episodes 18 months later. At this point the ejection fraction was 21% and a computed tomography scan revealed calcification of the aortic arch to the transverse arch. She had an aortic root replacement with pulmonary autograft.

Around this time, she had repeat X-rays which were felt to not be typical of psoriatic arthritis. Instead they showed acro-osteolysis with periarticular osteopaenia, and medullary widening. Subsequently given her other clinical features, Singleton-Merten Syndrome was diagnosed.

Conclusions Singleton-Merten Syndrome is a rare autosomal dominant multisystem condition with less than 10 cases reported in the literature. It is thought to be due to abnormal calcium deposition although its genetic basis is not known. Manifestations include aortic valve calcification, osteoporosis with widened medullary cavities, muscle weakness, short stature, psoriasiform eruptions, glaucoma and dentin dysplasia.

Rheumatologists commonly treat arthropathies and therefore although this is a rare cause we hope to highlight awareness of this syndrome.

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