Hyperechoic metaphyses in hypophosphatasia: what does it mean?

We report a case of hypophosphatasia diagnosed using US and CT at 29 weeks’ gestation and confirmed by molecular analysis. Prenatal US revealed very short fetal limbs and severe demineralization of the skull. The diaphyses were normal, but the metaphyses of the long bones appeared hyperechoic with no posterior shadowing. No fractures or long-bone deformations were observed. Three-dimensional helical CT performed at 29 weeks’ gestation provided additional details of the abnormal bones, i.e. irregular and cupped metaphyses that were very similar to the radiological findings of hypophosphatasia described postnatally. To our knowledge, the description of hyperechoic metaphyses in hypophosphatasia is unique and is a consequence of abnormal mineralization of the metaphyses that is specific to this pathology.