Multicentric carpal tarsal osteolysis
Multicentric carpal tarsal osteolysis is a rare skeletal disorder which is characterized by progressive osteolysis of the carpal, metacarpal and tarsal bones. It usually presents in early childhood with progressive pain and stiffness of the wrist, feet and elbow, clinically mimicking juvenile rheumatoid arthritis. This leads to joint deformities and is also often associated with chronic renal failure.
Multicentric carpal tarsal osteolysis syndrome is inherited in an autosomal dominant fashion with complete penetrance. It is caused by mutations in the MAFB (MAF BZIP transcription factor B) gene .
Most people with multicentric carpal tarsal osteolysis will have symptoms of cachexia, carpal osteolysis, EMG abnormality, gait disturbance, limited joint mobility, micrognathia, proptosis, proteinuria, wrist swelling, slender long bone, triangular face, and metacarpal osteolysis. Less common symptoms are camptodactyly of the finger, telecanthus, wide nasal bridge and downturned corners of mouth. Nephropathy can also occur which can lead to end-stage renal failure .
The pathogenesis of multicentric carpal tarsal osteolysis is still uncertain. It is thought that a mutation in the MAFB gene causes an imbalance in bone remodeling hence leading to osteolysis .
Plain radiographs show the characteristic appearance of the progressive destruction of carpal and tarsal bones with relatively preserved metacarpals and phalanges. During the early stages, there is progressive demineralization of the carpal and tarsal bones with loss of bone contours. In the later stages, this progresses to resorption of adjacent tubular bones leading to the tapering of the proximal ends of the metacarpals and metatarsals with a characteristic "sucked candy" appearance .
Treatment and prognosis
Multicentric carpal tarsal osteolysis syndrome is a very rare disorder and no specific treatment exists yet for this condition .