A 43-year-old man with the acquired immunodeficiency syndrome had clinical evidence of multifocal disease of the brain, but computed tomography was negative. Magnetic resonance imaging revealed multifocal lesions, histologically proven to be caused by cytomegalovirus. Therapy with 9[2-hydroxy-1-(hydroxymethyl) ethoxymethyl] guanine (BW B759U) resulted in stabilization of the patient's clinical disease and radiographic improvement of the lesions.
