Summary
Cases of cystic bone lesions in horses and humans were reviewed in the literature.
These lesions are radiolucent areas of bone, recognized as 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 similar, consisting of lesions with a distinct cyst wall, and a cavity filled
with fibrous tissue and yellowish mucoid fluid. The lesions are surrounded 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 aetiology and pathogenesis is still unknown, although primary damage to the
subchondral bone, cartilage or local blood supply and growth disturbances are discussed.
In this review 703 lesions of SCL in horses, 289 lesions of IOG and 1460 lesions of
UCB in humans were compared in their anatomical location and clinical signs. SCL and
OAC resembled each other with respect to anatomical location. A correlation of affected
bones could not be found for all four groups. Clinical presentation concerning age
was most similar for SCL and UCB with both lesions mainly occurring in young individuals.
Gender predominance of males was present in SCL, IOG and UCB. Clinical diagnosis was
either incidental, or connected with intermittent pain in all lesions except for OAC.
Additionally, the lesions were also found in conjunction with degenerative joint disease
(SCL, OAC) or pathological fractures (UCB). Cystic bone lesions were either treated
conservatively, surgically with curettage alone, curettage in combination with grafting
procedures, or intra-lesional application of corticosteroids. SCL and UCB were similar
in their biological behaviour concerning their slow response to the therapy and relatively
high recurrence rate. None of the cystic bone lesions were comparable, and a common
aetiology and pathogenesis could not be found.
In a literature review cases of cystic bone lesions in horses and humans were compared
with the goal to find a common aetiology and pathogenesis. Cystic bone lesions occur
in horses as subchondral cystic lesions (SCL), and in humans as either intra-osseous
ganglia (IOG), subchondral cystic lesions secondary to osteoarthrosis (OAC) or unicameral
bone cysts (UCB). IOG and OAC compare with SCL mainly in the anatomical location.
IOG and SCL resemble each other in size, clinical signs and histology, whereas UCB
and SCL show a similar biological behaviour regarding their therapeutic response and
recurrence rate. None of the cystic bone lesions in humans were comparable to the
SCL in horses in all aspects. A common aetiology and pathogenesis could not be established.
Keywords
Cystic bone lesions - subchondral cystic lesions - intra-osseous ganglion - subchondral
cystic lesions secondary to osteoarthrosis - unicameral bone cysts