The incidences of the five imaging signs were as follows: A) visualization on both sagittal and axial images (12/12, 100%), B) dural penetration (10/12, 83.3%), C) associated tethered cord (7/12, 58.3%), D) presence of tumor or inflammation (4/12, 33.3%), and E) attachment to the conus medullaris (4/12, 33.3%).
Nine of these tumors (1 ESN, 8 ESSs, and 1 UES) exhibited unusual histologic features, including smooth muscle (3), sex cord (7), epithelioid (1), fibromyxoid (1), and skeletal muscle (2) differentiation.
Gene-expression microarray analysis of RIMs (n = 5) compared to non-RIMs (MEN, n = 6) and a panel of other tumors (n = 62) showed that RIM gene-expression was similar to that seen in MEN, and by clustering analysis did not separate from them.