The hair on end sign refers to a radiographic appearance of the diploic space of the skull vault which results from a thickening of trabeculae as the diploic space expands. These trabeculae are perpendicular in orientation, interspersed by radiolucent marrow hyperplasia along the skull vault.
It is classically described with plain skull radiographs although can also be appreciated on CT or MRI 3. Causes include:
HI NEST 4
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