Bright rim sign (DNET)

Last revised by Joshua Yap on 13 Oct 2022

The bright rim sign, also known as the hyperintense ring sign, has been described in dysembryoplastic neuroepithelial tumors (DNET). It is described as a well-defined rim of high signal around the DNET on FLAIR sequences. This T2/FLAIR hyperintense ring, whether complete or incomplete, is fairly sensitive and specific for DNET 2. On postoperative imaging, this sign may be a helpful clue for residual tumor or tumor recurrence 2

On pathologic examination, this bright rim sign corresponds to glioneural elements loosely packed at the margin of the tumor 1.

This sign can, however, be very difficult to distinguish from the T2/FLAIR mismatch sign seen in astrocytomas, IDH-mutant.

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Cases and figures

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