Rare presentation of BK encephalitis in a child: imaging and pathological findings.

Clinically apparent BK virus infections mostly involve the genitourinary system of immunocompromised patients, particularly those who have undergone renal or bone marrow transplantations. Central nervous system involvement is extremely rare. In this report, we describe the pathologic and MR findings of BK encephalitis in a child. Initial involvement of the brainstem and the cervicomedullary junction was noted that later rapidly progressed to involve other regions of the supratentorial brain parenchyma including the basal ganglia and the thalami as well as the cerebellum.