Herpes simplex pancreatitis.

Lesions of the pancreas induced by viral infection have drawn relatively little attention because of their low incidence, and the histopathologic features of viral pancreatitis have not been fully elucidated. We report the autopsy findings of 2 patients, a 59-year-old woman with allergic granulomatous angiitis and a 73-year-old man with invasive pulmonary aspergillosis who had a disseminated visceral herpes simplex virus (HSV) infection. In both cases, the liver was the organ most severely affected by the viral infection. The pancreas showed multiple small foci of hemorrhagic necrosis, which were not accompanied by fat necrosis of the surrounding adipose tissue. Histopathologically, Cowdry type A intranuclear inclusions and a ground-glass appearance of the nuclei were found in many degenerated acinar cells around the necrotic foci. The gross appearance and histopathologic features of HSV pancreatitis were characteristic and, in particular, distinct from those of the more common acute hemorrhagic pancreatitis. Immunohistochemistry using an anti-HSV antibody revealed immunoreactivity in the intranuclear inclusions and ground-glass nuclei, and polymerase chain reaction analysis disclosed that the causative virus in these 2 cases was HSV-1. Herpes simplex virus pancreatitis constitutes a rare, but distinct pathologic entity among a group of acute pancreatitis diseases with diverse etiopathogenesis.