The characteristics of positive and confusing hand X-ray signs in diagnosing Kashin-Beck Disease in children in China.

When screening for Kashin-Beck disease (KBD) in children, hand X-ray examination is the most important measure. However, there is high rate of misdiagnosis because of confusing X-ray signs. We studied the characteristics of positive and confusing hand X-ray signs. Clinical and radiological examinations were conducted in all 7- to 12-year-olds in selected villages from some KBD and non-KBD areas. We analysed the radiological and epidemiological characteristics of the X-ray signs of KBD and the confusing signs. Images from 3,193 children were valid. No cases of KBD were found. Seventeen children (0.53%) had X-ray signs positive for KBD. The confusing X-ray signs included closure reaction of metaphysis-epiphysis (CRME, 14.28%), thumb variation (0.22%), little finger variation (8.89%), the second metacarpal-phalangeal variation (0.13%) and cystic change (3.85%). The onset of CRME in children occurred earlier in girls (9) than in boys (10). The onset occurred earlier in KBD areas (9) than in non-KBD areas (10). The onset occurred earlier in Han children (9) than in Tibetan children (11). In summary, KBD was effectively controlled in all investigated KBD endemic villages, and the age range should be adjusted to 7- to 11-year-olds in Han children to reduce the misdiagnosis rates in KBD surveillance.