MR and CT imaging of 24 pleomorphic xanthoastrocytomas (PXA) and a review of the literature.

INTRODUCTION

The aim of our study was to review the imaging appearance of PXA, a rare and usually low-grade, astrocytic tumor that typically occurs in young adults.

METHODS

The clinical presentation, location and imaging findings on CT (n = 15) and MR (n = 18) of 24 pathologically confirmed PXA were retrospectively reviewed. Two morphologic patterns were defined according to imaging features. The Mann-Whitney U-test was used for statistical analysis of the data.

RESULTS

All the neoplasms were supratentorial and superficial in location with obvious leptomeningeal contact in 22 patients, although leptomeningeal enhancement was demonstrated in only 3. Common locations were temporal (42%), frontal (33%) and parietal (21%), and more than one lobe was involved in 21% of patients. On CT without contrast enhancement, PXA was an iso- or hypoattenuating mass, and calcification was seen in six tumors and inner table remodeling was seen in three patients younger than 12 years. On MR, the solid component of PXA was isointense relative to gray matter on T1-weighted images, hyperintense on T2-weighted images in more than 90% and enhanced intensely following intravenous contrast material administration. Cystic areas showed hyperintensity relative to CSF. Two imaging patterns were differentiated: first a cystic mass containing a mural nodule (70%) and second a predominantly solid mass that may show cystic changes (30%).

CONCLUSION

The most consistent imaging features of PXA were a superficial location, leptomeningeal contact, and enhancement of the solid component. Apart from the classical PXA appearance of a cystic lesion with an enhancing mural nodule, a second pattern consisting of a predominantly solid mass was recognized.