Parietal bone agenesis with gracile bones and splenic hypoplasia/aplasia: clinico-pathologic report and differential diagnosis with review of cranio-gracile bone syndromes, "osteocraniostenosis" and Kleeblattschädel.

The findings in a newborn male with agenesis of parietal bones, gracile long bones, and hypoplasia of the spleen are presented. Although parietal agenesis is unique, the findings are compatible with 18 previously reported cases characterized by cranial hypomineralization, Kleeblatschädel, gracile bones, and splenic aplasia/hypoplasia, the nomenclature for which has been descriptive: gracile bone disorders, "osteocraniostenosis," "osteocraniosplenic syndrome." The term "osteocraniostenosis" may be inappropriate in that craniostenosis has been infrequently reported, a feature also of importance with respect to the pathogenesis of the Kleeblatschädel. The group likely reflects heterogeneous etiology and pathogenesis. Precedent, however, including animal models, justifies consideration of genetic aberrations, in particular, mutations in homeobox genes. (c) 2006 Wiley-Liss, Inc.