Familial occurrence of hyperplastic callus in osteogenesis imperfecta.

There is a hypothesis that hyperplastic callus (HC) in osteogenesis imperfecta (OI) is not merely a rare complication but could actually be inherited, although this idea has not yet been investigated. We described two cases, a mother and son, with mild OI, normal scleral colour and no dentinogenesis imperfecta, who repeatedly had HC in their femur. Familial occurrence of HC was found in 13 cases in 5 families among 21 cases in 7 families with a familial background of OI in the literature (including this report). This is higher than the reported incidence of HC, 1.5% (5 cases of 333), and the mode of transmission is concomitant with autosomal dominant inheritance in all these families. Since a review of 47 cases in the literature shows that HC occurs independently of scleral colour and the degree of bone fragility, it may be an additional criterion for subdivision within each type of the Sillence classification.