Metaphyseal chondrodysplasia with cone-shaped epiphyses: a specific form involving the lower limbs.

Three unrelated patients affected by a characteristic metaphyseal chondrodysplasia with cup-shaped metaphyses of the knees are described. Lower femoral and upper tibial cone-shaped epiphyses were embedded in the metaphyses. Main clinical features are short stature, shortening of the lower limbs, limitation of knee extension, and normal hands length. Radiographs of skull, spine, and hands showed no abnormality. This particular appearance of the knees has been seldom described in acquired disease such as repeated injuries, meningococcemia, scurvy, and hypervitaminosis A. Metaphyseal dysplasias with these distinctive radiological findings of the knees are uncommon. Differential diagnosis includes trichoscyphodysplasia and acroscyphodysplasia among others. Two other cases reported by Kozlowski showed the most similarities to our three cases and defined a new form of metaphyseal dysplasia with specific lower limbs involvement and cup-shaped metaphyses.