[The "lamellar cranium": a particular radiologic feature of Cooley's disease].

The skull in homozygous beta-thalassemia (Cooley's anemia) may present with 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 aspect owing to a variable number of osseous lamellae, arranged so as to be parallel to the inner table. This "lamellated skull" was observed in 16 patients, selected from 150 patients with Cooley's anemia (10.6%). The possible mechanisms are discussed. The pluristratified lamellar osseous production could be brought about by repeated periosteal osteoblastic reaction to the sinusoidal neovascularization associated with marrow hyperplasia in poorly or not at all transfused patients.