Background Early joint involvement in certain types of mucopolysaccharidoses (MPS) can lead to initial referral to a pediatric rheumatologist or orthopedic surgeon because of suspicion of juvenile idiopathic arthritis or other joint disease . We document here the case of a male patient who was treated for Legg-Calvé-Perthes Disease of the right hip at an orthopedic center at 3 years of age after presenting with a limp, and who was subsequently diagnosed with mucopolysaccharidosis II (Hunter Syndrome) 18 months later.
Objectives We hope to highlight the significance of joint involvement in the disease course of a young MPS patient, and relate an example of the often complicated route to a final diagnosis in the various attenuated forms of MPS.
Results Upon the patient’s arrival at our department, only a slight limp was apparent, which did not significantly affect the everyday life of the active 5 year old. An X-ray examination showed pronounced degenerative changes in both hips. Subsequent review of the hip X-ray performed at the age of 3 years revealed relatively minor changes in the left femoral head with involvement of the acetabulum bilaterally, in addition to the damage originally noted in the right femoral head. His urinary glycosaminoglycan (GAG) concentration was pathologically elevated (220 mg/g creatinine, norm: <60mg/g), including abnormal fractions of dermatan and heparan sulfate, and the iduronate-2-sulfatase (IDS) enzyme activity was close to zero. Genetic testing revealed an as yet unpublished missense mutation in the iduronate sulfatase gene. The physical features of MPS II, including joint contractures, dysostosis multiplex, coarse facies, hepatomegaly and umbilical hernia are recognizable in our patient, but there is no sign of central nervous system involvement. Enzyme replacement therapy (ERT) with idursulfase (Elaprase) was started in May, 2011.
Conclusions Through the presentation of this case we hope to encourage the inclusion of mucopolysaccharidosis and other lysosomal storage diseases, when appropriate, in the differential diagnostic spectrum of cases of joint disease which is atypical, or in cases where the etiology is uncertain.
Cimaz, R., et al., Joint contractures in the absence of inflammation may indicate Mucopolysaccharidosis. Pediatric Rheumatology, 2009, 7:18.
Disclosure of Interest None Declared
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