Biparietal osteodystrophy: Macroscopic appearance, computed tomography imaging and microarchitectural analysis.

Anatomical or morphological variations of the skull bones usually do not attract much attention among forensic pathologists. However, these variations can sometimes be an important marker in forensic identification of a person or represent a missing piece when solving a cranial trauma puzzle. In this article, we were interested in peculiar presentation of the thinning of both parietal bones (biparietal osteodystrophy). The course and etiology of this condition still remain unknown. In three autopsy cases with biparietal osteodystrophy (three females aged 95, 90 and 83) and no head trauma, we used conventional (CT) and microcomputed tomography (micro-CT) imaging of the skull and parietal bone specimens containing normal bone, transitional zone and thinned bone with osteodystrophy. CT images demonstrated an oval-shaped resorptive parietal bone depression with smooth contours, without marginal osteosclerotic changes or involvement of cranial sutures. In the transitional zone, micro-CT scans showed a decrease in total bone thickness and the thickness of diplöe, while inner and outer tables showed increased porosity. At the site of maximal thinness of the parietal bone, inner and outer tables fused and formed a thin layer of cortical bone. Skull thinning appeared due to the reduced thickness of diplöe, leading to egg-shell thinning in the central area of the parietal bones. A forensic pathologist should be familiar with this benign condition in order not to confuse it with resorptive bone diseases.