The "lamellated" skull in beta-thalassaemia.

The skull in homozygous beta-thalassaemia may present several abnormalities, such as osteopenia, widening of the diploic space, and a "hair-on-end" appearance. In some cases it presents also a particular stratified appearance caused by a variable number of osseous lamellae, parallel with the inner table. This "lamellated skull" was observed in 16 out of 150 patients affected by the disease (10.6%). Possible mechanisms are discussed. The lamellar osseous changes could be due to repeated periosteal osteoblastic reactions to the sinusoidal neovascularization associated with marrow hyperplasia in poorly transfused patients.