The orthopedic and renal manifestations of idiopathic carpal tarsal osteolysis

Multicentric carpotarsal osteolysis syndrome (MCTO) with generalized high bone turnover and high serum RANKL: Response to denosumab

MCTO is a rare disorder, caused by mutations in the MafB gene, a negative regulator of receptor activator of nuclear factor-кB ligand (RANKL). Manifestations include carpal and tarsal osteolysis and renal failure. Pathophysiology is poorly understood, and no effective treatment is available.

In this case report we describe a patient with MCTO (MafB, mutation c.206C>T, p.Ser69Leu), diagnosed at the age of 5 years. At 7 years, skeletal survey showed diffuse osteopenia. BMD was mildly reduced, and bone turnover markers increased. He was treated with denosumab, a human monoclonal RANKL inhibitor for two years. Each injection was followed by a marked reduction in C-telopeptide (CTX). Following denosumab his BMD and bone symptoms improved and the osteolysis stabilized. At the age of 13 years, osteoporosis was diagnosed using high resolution peripheral quantitative computed tomography (HRpQCT) and serum RANKL was found to be markedly increased.

This initial experience suggests that the associated osteoporosis may be ameliorated by denosumab, although further study will be needed to understand the appropriate dose, frequency, and the extent of efficacy. Monitoring of CTX and bone specific alkaline phosphatase will be especially useful in this regard. Further study in other MCTO patients is also needed to determine whether high bone turnover is specific to this mutation or more common than previously appreciated. We propose a model in which osteolysis in this condition is strongly associated with the systemic osteoporosis.

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MCTO (MafB gene mutation (c.206C>T,p.Ser69Leu) is associated with osteoporosis and very high levels of serum RANKL.

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Denosumab appears to ameliorate the osteoporosis. Further study is needed regarding the dose and frequency of injections.

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Examination of the frequency of osteoporosis and association with osteolysis is needed in MCTO

Multicentric carpotarsal osteolysis syndrome: long-term follow-up of three patients

Multicentric carpotarsal osteolysis (MCTO) is a rare skeletal disorder characterized by progressive carpal and tarsal destruction. The upper and lower limbs may be involved, leading to deformities and joint limitation. These anatomic features may be associated with progressive renal failure. The radiographs obtained during childhood showed a carpal and tarsal osteolysis and an asymmetrical involvement. Here, we report on the long-term clinical and radiological findings of three patients with skeletal manifestations of MCTO.

[Multicentric carpotarsal osteolysis in a rheumatologist's practice]

Multicentric carpotarsal osteolysis (MCTO) syndrome is a rare skeletal dysplasia associated with missense mutation in the MAFB gene, usually manifesting in young childhood, and showing variative phenotypic signs and course. The clinical manifestations of the syndrome include aggressive osteolysis predominantly of carpal and tarsal bones, progressive nephropathy, and mild craniofacial anomalies. The similarity between the initial clinical manifestations of MCTO and the symptoms of childhood inflammatory joint diseases makes a diagnosis very difficult, in the early stages of the disease in particular, and frequently leads to the ungrounded use of long-term immunosuppressive therapy. The paper describes a familial case of MCTO without affecting the kidneys in the mother and daughter.