The nature of cartilage stippling in chondrodysplasia punctata: histopathological study of Conradi-Hünermann syndrome.

The chondrodysplasia punctatas (CDP) are a group of genetic diseases presenting with the common hallmark of epiphyseal calcific deposits. A 21.3 week female fetus with a clinical and molecular diagnosis of X-linked dominant CDP (CDPX2 or Conradi-Hunermann syndrome) has been investigated with particular attention to the morphology of the calcific deposits (stipplings). A variable combination of normal endochondral ossification centers, calcific deposits, and a mixture of these two were observed in the lumbar spine. The calcific deposits were characterized by a growing phase, corresponding to the expansion of calcification, a steady phase, and a resorbing/remodeling phase, when calcification was progressively reduced through different biological mechanisms. The pathological mechanism of cartilage matrix calcification seemed to influence the morphology and the distribution pattern of vessels inside the epiphysis. These findings fit well with the radiographic observations of progressive regression of stippling with advancing age of the child and also give a morphological correlation.