FIG 1. Post-transplant lymphoproliferative disorder in a 6-year-old girl with new-onset seizures and worsening headaches 3 years after renal transplantation.

A, Axial T2-weighted image (TR/TE, 4000/97.28) shows bilateral hyperintense brain lesions, some of which are ringlike (arrow) and have extensive surrounding vasogenic edema.

B, Coronal T1-weighted image (TR/TE, 500/8), obtained after gadolinium administration, reveals bilateral enhancing foci in cerebral hemispheres (curved arrows) and corpus callosum (arrowhead), with patchy leptomeningeal enhancement (straight arrows).

C, Sagittal T1-weighted image obtained after gadolinium administration demonstrates ring enhancement in some of the larger foci (arrowhead) and enhancement in the smaller foci (arrow).

D, Microscopic specimen obtained at biopsy reveals diffuse large cell lymphoma (monomorphic post-transplant lymphoproliferative disorder) and tumor cells with prominent nucleoli and irregular nuclear contours (arrows) (hematoxylin and eosin, original magnification x40).

E, Microscopic specimen shows that the large dysplastic cells express the B-cell marker (CD20 antibody stain [Dako Corporation, Carpenteria, CA], original magnification x40).

F, G, Axial fluid-attenuated inversion recovery images (TR/TE, 8402/150), obtained 26 months after initial diagnosis, show resolution of most of the abnormal T2 hyperintensity with only small areas of abnormal signal intensity remaining (arrows), none of which enhanced.