Lethal chondrodysplasia punctata, Conradi Hünermann subtype A, one case

Ichthyosis and Keratotic Follicular Plugs Containing Dystrophic Calcification in Newborns

Prior to the recent characterization of the enzymatic defect and identification of the involved gene, the histopathology of X-linked dominant chondrodysplasia punctata (Conradi-Hünermann-Happle syndrome or CDPX2) has been described under various names including calcinosis universalis, chondrodystrophia calcificans congenita, Conradi disease, and Conradi-Hünermann syndrome. We present two newborns with characteristic ichthyosiform erythroderma noted at birth. Radiographs demonstrated chondrodysplasia punctata in one patient. Although the x-ray performed at birth was negative in the other patient, sterol analyses of the keratotic scales were diagnostic for CDPX2. Skin biopsies from both patients showed thick laminated orthokeratosis and prominent keratotic follicular plugs containing dystrophic calcification. We also retrospectively examined 20 cases of various types of ichthyosis seen over a 23-year period at our institution. Intracorneal calcium deposition was not seen in any of these cases. As demonstrated by our cases and review of the literature, dystrophic calcification in the keratotic plug is a distinctive histopathologic feature of Conradi-Hünermann-Happle syndrome in newborns and is not seen in other known forms of ichthyoses.

Cutaneous histopathology of Conradi-Hunermann syndrome

The histopathology of the skin in the ichthyosiform erythroderma associated with classical Conradi-Hunermann syndrome has been rarely described. Skin biopsies from 2 infants with the classical features of Conradi-Hunermann syndrome including ichthyosiform erythroderma contained hyperkeratosis, dilated ostia of pilosebaceous structures, and calcium salts in the stratum corneum detectable with special stains. An unusual feature of one case was dilatation of acrosyringeal structures. We hypothesize that dilatation of acrosyringeal structures is analogous to the plugging noted in pilosebaceous units. Taken together, the ichthyosiform erythroderma of Conradi-Hunermann has a distinctive histologic appearance.

Radiologic nosology of bone dysplasias

The usefulness of radiodiagnostics in the delineation of bone dysplasias is exemplified by an attempt to classify the lethal osteochondrodysplasias. Based on morphologic criteria these disorders are subdivided into 11 major categories. Within these categories pathogenetically related bone dysplasia families can be discerned. Radiology meets its limits when different mutations lead to identical or overlapping phenotypes. In the future radiology will keep its prominent place in the diagnosis and nosology of inborn errors of skeletal development because of its ready availability, speed, non-invasiveness, and discriminating power. As shown by disorders such as metatropic dysplasia or iduronidase deficiency, radiology is most important to evaluate the prognosis of a given condition.