Fatal BK polyoma viral pneumonia associated with immunosuppression.

BK polyoma virus has a worldwide distribution in the human population. Primary BK infection takes place during childhood, with the virus remaining latent in many sites. Immunosuppressive states can lead to viral reactivation associated with many clinical sequelae. We report a case of fatal BK-related pneumonia in a 69-year-old patient who was immunocompromised because of chemotherapy for chronic lymphocytic leukemia. Immunohistochemical, in situ hybridization, and polymerase chain reaction studies on paraffin-embedded lung tissue proved BK virus as the etiologic agent of pneumonia. The histological picture was remarkable for numerous intranuclear large basophilic viral inclusions with ground-glass appearance mainly in type II pneumocytes. Similar to many other infectious agents, BK virus is emerging as an important pathogen in immunocompromised patients, making it important to consider in the differential diagnosis.