脊椎骨幹端異形成症の1例

Spondylometaphyseal Dysplasia : Case Report

　抄録：扁平椎，下肢中心の骨幹端異形成を伴った稀なspondylometaphyseal dysplasia（以下SMDと略）の1例を経験したので報告する．症例は，5歳8カ月の女児．主訴はO脚，低身長．家族歴，出生歴に問題はなく，11カ月にて処女歩行開始．発達の遅延はみられなかった．躯幹短縮型の小人症で，顔貌は正常，角膜混濁はなく，知能，視力，聴力も正常，歩行は家鴨様であった．X線上，扁平椎，長管骨骨幹端異形成の他，Kozlowski型SMDに特徴的な所見がみられていた．本疾患に特異的な治療法はなく，予後は良好で，変形が強い場合には矯正骨切り術が必要となるが，O脚は改善傾向にあり，現在は経過観察中である．SMDの類似疾患は多数存在し，表現型も多彩であり，今後，その診断や分類について明確にしていく必要がある．

　Spondylometaphyseal dysplasia (SMD) is a rare form of skeletal dysplasia with characteristic radiographic findings. We report the case of a 5-year-old Japanese girl with typical SMD manifested by platyspondyly and severe metaphyseal changes of the long bones of the lower limbs. Her stature was short；her trunk was short；and she exhibited genu varum deformity. At 5 years of age her body height was 93 cm (-3.7 SD) and she weighted 17.0 kg (-0.7 SD). The patient, was the second child of non-consanguineous parents, and her developmental milestones were normal. The patient was able to walk at 11 months of age, but had a “waddling gait”. Her faces did not manifest any specific features of chromosomal abnormalities；there was no corneal clouding or hearing loss；and her motor and mental development had been normal. The serum calcium, phosphorus, and alkaline phosphatase values were within their normal ranges, and a toluidine blue spot test showed no accumulation of mucopolysaccharides. Radiographs revealed platyspondyly with rounding of the vertebral bodies, generalized irregular metaphyses of the long bones, bilateral coxa vara, and retarded skeletal age of the carpal bones. These radiological features of the patient are classified descriptively as the most common form, the Kozlowski type. Although development of severe deformities of the lower limbs may require corrective osteotomy, her deformities have been improving and we do not think that the osteotomy is indicated at this point.