Primary central nervous system lymphomas (PCNSL): MRI response criteria revised.

The authors investigated the applicability of Macdonald response criteria to patients with primary CNS lymphoma (PCNSL). Four of 68 patients with persisting contrast-enhancing lesions after primary therapy did not receive further therapy, and none showed tumor progression after up to 54 months. Because contrast enhancement may not necessarily indicate residual, biologically active lymphoma, the authors propose a modification of the Macdonald response criteria.