Figure 1. Brain imaging and autopsy findings in a case of chronic Jamestown Canyon virus (JCV) meningoencephalitis in a patient receiving rituximab, Boston, Massachusetts, USA. A) Brain magnetic resonance imaging T2-weighted fluid-attenuated inversion recovery showed mild atrophy with secondary ventriculomegaly but was otherwise unremarkable. B) Brain positron emission tomography with 2-deoxy-2-[fluorine-18] fluoro-D-glucose integrated with computed tomography showed global hypometabolism. Color scale ranges from blue-green (hypometabolic) to orange-white (hypermetabolic). C, D) Hematoxylin and eosin stained section of cerebral cortex at low magnification shows loss of neurons and perivascular chronic inflammation (C), compared with a JCV-negative control with a normal complement of cortical neurons (D). E, F) Higher-power magnification of cerebral cortex (E) and hippocampus (F) show microgliosis, microglial nodules, and neuronophagia (arrow). G, H) Severe Purkinje cell loss, Bergmann gliois (arrows), and microgliosis (arrowheads) of the molecular layer are present in the cerebellum (G), compared with a JCV-negative control with normal complement of Purkinje cells (H). I, J) Immunohistochemistry shows abundant perivascular, parenchymal, and leptomeningeal CD3+ T cells (I) and is negative for B-cell lineage–specific activator protein positive B cells (J). Panels C, D, I, and J, original magnification ×100; panels E, F, G, and H, original magnification ×200.