Osteoporosis circumscripta cranii refers to discrete radiolucent regions of the skull on plain radiographs. It is due to the extensive loss of bone density (lysis) involving the bilateral parietal and occipital bones, and the right temporal bone. The appearance is characteristic of the lytic phase of Paget disease and is often referred to as osteoporosis circumscripta. Credits: https://www.instagram.com/p/CQs2gSNL2lq/?utm_medium=copy_link