CYSTIC BONE-LESIONS IN HORSES AND HUMANS - A COMPARATIVE REVIEW

Cases of cystic bone lesions in horses and humans were reviewed in the literature. These lesions are radiolucent areas of bone, recognized a s subchondral cystic lesions in the horse (SCL), intra-osseous ganglia (IOG), subchondral bone cysts secondary to osteoarthrosis (OAC), and unicameral bone cysts (UCB) in humans. Their morphology is quite simil ar, consisting of lesions with a distinct cyst wall, and a cavity fill ed with fibrous tissue and yellowish mucoid fluid. The lesions are sur rounded by sclerotic bone and can be easily diagnosed radiographically . SCL, IOG and OAC occur in the subchondral bone close to the adjacent joint, whereas UCB occur in the metaphysis of long bones. Their aetio logy and pathogenesis is still unknown, although primary damage to the subchondral bone, cartilage or local blood supply and growth disturba nces are discussed. In this review 703 lesions of SCL in horses, 289 l esions of IOG and 1460 lesions of UCB in humans were compared in their anatomical location and clinical signs. SCL and OAC resembled each ot her with respect to anatomical location. A correlation of affected bon es could not be found for all four groups. Clinical presentation conce rning age was most similar for SCL and UCB with both lesions mainly oc curring in young individuals. Gender predominance of males was present in SCL, IOG and UCB. Clinical diagnosis was either incidental, or con nected with intermittent pain in all lesions except for OAC. Additiona lly, the lesions were also found in conjunction with degenerative join t disease (SCL, OAC) or pathological fractures (UCB). Cystic bone lesi ons were either treated conservatively, surgically with curettage alon e, curettage in combination with grafting procedures, or intra-lesiona l application of corticosteroids. SCL and UCB were similar in their bi ological behaviour concerning their slow response to the therapy and r elatively high recurrence rate. None of the cystic bone lesions were c omparable, and a common aetiology and pathogenesis could not be found.