A case of acute acalculous cholecystitis complicated by primary Epstein-Barr virus infection.

Acute acalculous cholecystitis (AAC) is a rare complication of infectious mononucleosis (IM). An immunocompetent 6-year-old Japanese girl complained of epigastralgia during the course of IM. Ultrasonography (US) revealed a markedly thickened and sonolucent gallbladder wall. No gallstones were apparent. Antibodies against Epstein-Barr virus (EBV) confirmed primary EBV infection. Cytomegalovirus immunoglobulin M showed a false-positive result in the acute phase, probably due to cross-reaction to EBV nuclear antigen. We diagnosed her as AAC related with primary EBV infection. She recovered completely by conservative treatment. US should be performed in consideration of the possibility of AAC when a patient with IM complains of epigastralgia.