Case 148. BK virus infection of bladder (30 y-o F)
         
    Incidental autopsy findings of the urinary bladder in leukemia case 3 months after bone marrow transplantation    
         
   
Key words : BK virus, cystitis
   
         
   
opportunistic infection
   
     
 
     
Amphophilic intranuclear inclusion bodies are seen in the urothelial cells (HE). Inflammation is scarcely observed. Refer also to case 14.   Electron micrograph of the intranuclear inclusion of the urothelial cell in a paraffin section confirmed infection of small-sized viral particles, consistent with papova virus.
     
 
     
Reference case 148A
Urine cytology in case of SLE (22 y-o F) receiving corticosteroid.  Poorly cohesive urothelial cells possess amorphous and smudgy nuclei, indicative of BK viral infection. The "decoy cells" should be distinguished from cancer cells.
  Reference case 148A
Restaining of the cytology specimen for VP-1 antigen of SV-40, showing an antigenicity common to the papova viruses (left: Papanicolaou, right: immunostaining). VP-1 antigen of the papova virus is strongly expressed in the urothelial cells with nuclear inclusions.
     
   
     
Reference case 148A
Electron micrograph of the urine sediment. The nucleus of the urothelial cell possesses 50 nm-sized small viral particles.